*usr_41.txt* For Vim version 6.1. Last change: 2001 Oct 26
VIM USER MANUAL - by Bram Moolenaar
Write a Vim script
The Vim script language is used for the startup vimrc file, syntax files, and
many other things. This chapter explains the items that can be used in a Vim
script. There are a lot of them, thus this is a long chapter.
|41.1| Introduction
|41.2| Variables
|41.3| Expressions
|41.4| Conditionals
|41.5| Executing an expression
|41.6| Using functions
|41.7| Defining a function
|41.8| Various remarks
|41.9| Writing a plugin
|41.10| Writing a filetype plugin
|41.11| Writing a compiler plugin
Next chapter: |usr_42| Add new menus
Previous chapter: |usr_40| Make new commands
Table of contents: |usr_toc|
*41.1* Introduction *vimrc-intro* *vim-script-intro* Your first experience with Vim scripts is the vimrc file. Vim reads it when it starts up and executes the commands. You can set options to values you prefer. And you can use any colon command in it (commands that start with a ":"; these are sometimes referred to as Ex commands or command-line commands). Syntax files are also Vim scripts. As are files that set options for a specific file type. A complicated macro can be defined by a separate Vim script file. You can think of other uses yourself. Let's start with a simple example: > :let i = 1 :while i < 5 : echo "count is" i : let i = i + 1 :endwhile <Note:The ":" characters are not really needed here. You only need to use them when you type a command. In a Vim script file they can be left out. We will use them here anyway to make clear these are colon commands and make them stand out from Normal mode commands. The ":let" command assigns a value to a variable. The generic form is: > :let{variable}={expression}In this case the variable name is "i" and the expression is a simple value, the number one. The ":while" command starts a loop. The generic form is: > :while{condition}:{statements}:endwhile The statements until the matching ":endwhile" are executed for as long as the condition is true. The condition used here is the expression "i < 5". This is true when the variable i is smaller than five. The ":echo" command prints its arguments. In this case the string "count is" and the value of the variable i. Since i is one, this will print:count is 1Then there is another ":let i =" command. The value used is the expression "i + 1". This adds one to the variable i and assigns the new value to the same variable. The output of the example code is:count is 1count is 2count is 3count is 4Note:If you happen to write a while loop that keeps on running, you can interrupt it by pressingCTRL-C(CTRL-Breakon MS-Windows). THREE KINDS OF NUMBERS Numbers can be decimal, hexadecimal or octal. A hexadecimal number starts with "0x" or "0X". For example "0x1f" is 31. An octal number starts with a zero. "017" is 15. Careful: don't put a zero before a decimal number, it will be intepreted as an octal number! The ":echo" command always prints decimal numbers. Example: > :echo 0x7f 036< 127 30A number is made negative with a minus sign. This also works for hexadecimal and octal numbers. A minus sign is also for substraction. Compare this with the previous example: > :echo 0x7f -036< 97White space in an expression is ignored. However, it's recommended to use it for separating items, to make the expression easier to read. For example, to avoid the confusion with a negative number, put a space between the minus sign and the following number: > :echo 0x7f - 036
*41.2* Variables
A variable name consists of ASCII letters, digits and the underscore. It
cannot start with a digit. Valid variable names are:
counter
_aap3
very_long_variable_name_with_dashes
FuncLength
LENGTH
Invalid names are "foo+bar" and "6var".
These variables are global. To see a list of currently defined variables
use this command: >
:let
You can use global variables everywhere. This also means that when the
variable "count" is used in one script file, it might also be used in another
file. This leads to confusion at least, and real problems at worst. To avoid
this, you can use a variable local to a script file by prepending "s:". For
example, one script contains this code: >
:let s:count = 1
:while s:count < 5
: source other.vim
: let s:count = s:count + 1
:endwhile
Since "s:count" is local to this script, you can be sure that sourcing the
"other.vim" script will not change this variable. If "other.vim" also uses an
"s:count" variable, it will be a different copy, local to that script. More
about script-local variables here: |script-variable|.
There are more kinds of variables, see |internal-variables|. The most often
used ones are:
b:name variable local to a buffer
w:name variable local to a window
g:name global variable (also in a function)
v:name variable predefined by Vim
DELETING VARIABLES
Variables take up memory and show up in the output of the ":let" command. To
delete a variable use the ":unlet" command. Example: >
:unlet s:count
This deletes the script-local variable "s:count" to free up the memory it
uses. If you are not sure if the variable exists, and don't want an error
message when it doesn't, append !: >
:unlet! s:count
When a script finishes, the local variables used there will not be
automatically freed. The next time the script executes, it can still use the
old value. Example: >
:if !exists("s:call_count")
: let s:call_count = 0
:endif
:let s:call_count = s:call_count + 1
:echo "called" s:call_count "times"
The "exists()" function checks if a variable has already been defined. Its
argument is the name of the variable you want to check. Not the variable
itself! If you would do this: >
:if !exists(s:call_count)
Then the value of s:call_count will be used as the name of the variable that
exists() checks. That's not what you want.
The exclamation mark ! negates a value. When the value was true, it
becomes false. When it was false, it becomes true. You can read it as "not".
Thus "if !exists()" can be read as "if not exists()".
What Vim calls true is anything that is not zero. Only zero is false.
STRING VARIABLES AND CONSTANTS
So far only numbers were used for the variable value. Strings can be used as
well. Numbers and strings are the only two types of variables that Vim
supports. The type is dynamic, it is set each time when assigning a value to
the variable with ":let".
To assign a string value to a variable, you need to use a string constant.
There are two types of these. First the string in double quotes: >
:let name = "peter"
:echo name
< peter
If you want to include a double quote inside the string, put a backslash in
front of it: >
:let name = "\"peter\""
:echo name
< "peter"
To avoid the need for a backslash, you can use a string in single quotes: >
:let name = '"peter"'
:echo name
< "peter"
Inside a single-quote string all the characters are taken literally. The
drawback is that it's impossible to include a single quote. A backslash is
taken literally as well, thus you can't use it to change the meaning of the
character after it.
In double-quote strings it is possible to use special characters. Here are
a few useful ones:
\t <Tab>
\n <NL>, line break
\r <CR>, <Enter>
\e <Esc>
\b <BS>, backspace
\" "
\\ \, backslash
\<Esc> <Esc>
\<C-W> CTRL-W
The last two are just examples. The "\<name>" form can be used to include
the special key "name".
See |expr-quote| for the full list of special items in a string.
*41.3* Expressions Vim has a rich, yet simple way to handle expressions. You can read the definition here: |expression-syntax|. Here we will show the most common items. The numbers, strings and variables mentioned above are expressions by themselves. Thus everywhere an expression is expected, you can use a number, string or variable. Other basic items in an expression are: $NAME environment variable &name option @r register Examples: > :echo "The value of 'tabstop' is" &ts :echo "Your home directory is" $HOME :if @a > 5 The &option form can be used to save an option value, set it to a new value, do something and restore the old value. Example: > :let save_ic = &ic :set noic :/The Start/,$delete :let &ic = save_ic This makes sure the "The Start" pattern is used with the 'ignorecase' option off. Still, it keeps the value that the user had set. MATHEMATICS It becomes more interesting if we combine these basic items. Let's start with mathematics on numbers: a + b add a - b subtract a * b multiply a / b divide a % b modulo The usual precedence is used. Example: > :echo 10 + 5 * 2< 20Grouping is done with braces. No suprises here. Example: > :echo (10 + 5) * 2< 30Strings can be concatenated with ".". Example: > :echo "foo" . "bar"< foobarWhen the ":echo" command gets multiple arguments, it separates them with a space. In the example the argument is a single expression, thus no space is inserted. Borrowed from the C language is the conditional expression: a ? b : c If "a" evaluates to true "b" is used, otherwise "c" is used. Example: > :let i = 4 :echo i > 5 ? "i is big" : "i is small"< i is smallThe three parts of the constructs are always evaluated first, thus you could see it work as: (a) ? (b) : (c)
*41.4* Conditionals The ":if" commands executes the following statements, until the matching ":endif", only when a condition is met. The generic form is: :if{condition}{statements}:endif Only when the expression{condition}evaluates to true (non-zero) will the{statements}be executed. These must still be valid commands. If they contain garbage, Vim won't be able to find the ":endif". You can also use ":else". The generic form for this is: :if{condition}{statements}:else{statements}:endif The second{statements}is only executed if the first one isn't. Finally, there is ":elseif": :if{condition}{statements}:elseif{condition}{statements}:endif This works just like using ":else" and then "if", but without the need for an extra ":endif". A useful example for your vimrc file is checking the 'term' option and doing something depending upon its value: > :if &term == "xterm" : " Do stuff for xterm :elseif &term == "vt100" : " Do stuff for a vt100 terminal :else : " Do something for other terminals :endif LOGIC OPERATIONS We already used some of them in the examples. These are the most often used ones: a == b equal to a != b not equal to a > b greater than a >= b greater than or equal to a < b less than a <= b less than or equal to The result is one if the condition is met and zero otherwise. An example: > :if v:version >= 600 : echo "congratulations" :else : echo "you are using an old version, upgrade!" :endif Here "v:version" is a variable defined by Vim, which has the value of the Vim version. 600 is for version 6.0. Version 6.1 will have the value 601. This is very useful to write a script that works with multiple versions of Vim. |v:version| The logic operators work both for numbers and strings. When comparing two strings, the mathematical difference is used. This compares byte values, which may not be right for some languages. When comparing a string with a number, the string is first converted to a number. This is a bit tricky, because when a string doesn't look like a number, the number zero is used. Example: > :if 0 == "one" : echo "yes" :endif This will echo "yes", because "one" doesn't look like a number, thus it is converted to the number zero. For strings there are two more items: a =~ b matches with a !~ b does not match with The left item "a" is used as a string. The right item "b" is used as a pattern, like what's used for searching. Example: > :if str =~ " " : echo "str contains a space" :elseif str !~ '\.$' : echo "str ends in a full stop" :endif Notice the use of a single-quote string for the pattern. This is useful, because backslashes need to be doubled in a double-quote string and patterns tend to contain many backslashes. The 'ignorecase' option is used when comparing strings. When you don't want that, append "#" to match case and "?" to ignore case. Thus "==?" compares two strings to be equal while ignoring case. And "!~#" checks if a pattern doesn't match, also checking the case of letters. For the full table see |expr-==|. MORE LOOPING The ":while" command was already mentioned. Two more statements can be used in between the ":while" and the ":endwhile": :continue Jump back to the start of the while loop; the loop continues. :break Jump forward to the ":endwhile"; the loop is discontinued. Example: > :while counter < 40 : call do_something() : if skip_flag : continue : endif : if finished_flag : break : endif : sleep 50m :endwhile The ":sleep" command makes Vim take a nap. The "50m" specifies fifty milliseconds. Another example is ":sleep 4", which sleeps for four seconds.
*41.5* Executing an expression So far the commands in the script were executed by Vim directly. The ":execute" command allows executing the result of an expression. This is a very powerful way to build commands and execute them. An example is to jump to a tag, which is contained in a variable: > :execute "tag " . tag_name The "." is used to concatenate the string "tag " with the value of variable "tag_name". Suppose "tag_name" has the value "get_cmd", then the command that will be executed is: > :tag get_cmd The ":execute" command can only execute colon commands. The ":normal" command executes Normal mode commands. However, its argument is not an expression but the literal command characters. Example: > :normal gg=G This jumps to the first line and formats all lines with the "=" operator. To make ":normal" work with an expression, combine ":execute" with it. Example: > :execute "normal " . normal_commands The variable "normal_commands" must contain the Normal mode commands. Make sure that the argument for ":normal" is a complete command. Otherwise Vim will run into the end of the argument and abort the command. For example, if you start Insert mode, you must leave Insert mode as well. This works: > :execute "normal Inew text \<Esc>" This inserts "new text " in the current line. Notice the use of the special key "\<Esc>". This avoids having to enter a real<Esc>character in your script.
*41.6* Using functions
Vim defines many functions and provides a large amount of functionality that
way. A few examples will be given in this section. You can find the whole
list here: |functions|.
A function is called with the ":call" command. The parameters are passed in
between braces, separated by commas. Example: >
:call search("Date: ", "W")
This calls the search() function, with arguments "Date: " and "W". The
search() function uses its first argument as a search pattern and the second
one as flags. The "W" flag means the search doesn't wrap around the end of
the file.
A function can be called in an expression. Example: >
:let line = getline(".")
:let repl = substitute(line, '\a', "*", "g")
:call setline(".", repl)
The getline() function obtains a line from the current file. Its argument is
a specification of the line number. In this case "." is used, which means the
line where the cursor.
The substitute() function does something similar to the ":substitute"
command. The first argument is the string on which to perform the
substitution. The second argument is the pattern, the third the replacement
string. Finally, the last arguments are the flags.
The setline() function sets the line, specified by the first argument, to a
new string, the second argument. In this example the line under the cursor is
replaced with the result of the substitute(). Thus the effect of the three
statements is equal to: >
:substitute/\a/*/g
Using the functions becomes more interesting when you do more work before and
after the substitute() call.
FUNCTIONS *function-list*
There are many functions. We will mention them here, grouped by what they are
used for. You can find an alphabetical list here: |functions|. Use CTRL-] on
the function name to jump to detailed help on it.
String manipulation:
char2nr() get ASCII value of a character
nr2char() get a character by its ASCII value
escape() escape characters in a string with a '\'
strtrans() translate a string to make it printable
tolower() turn a string to lowercase
toupper() turn a string to uppercase
match() position where a pattern matches in a string
matchend() position where a pattern match ends in a string
matchstr() match of a pattern in a string
stridx() first index of a short string in a long string
strridx() last index of a short string in a long string
strlen() length of a string
substitute() substitute a pattern match with a string
submatch() get a specific match in a ":substitute"
strpart() get part of a string
expand() expand special keywords
type() type of a variable
Working with text in the current buffer:
byte2line() get line number at a specific byte count
line2byte() byte count at a specific line
col() column number of the cursor or a mark
virtcol() screen column of the cursor or a mark
line() line number of the cursor or mark
wincol() window column number of the cursor
winline() window line number of the cursor
getline() get a line from the buffer
setline() replace a line in the buffer
append() append {string} below line {lnum}
indent() indent of a specific line
cindent() indent according to C indenting
lispindent() indent according to Lisp indenting
nextnonblank() find next non-blank line
prevnonblank() find previous non-blank line
search() find a match for a pattern
searchpair() find the other end of a start/skip/end
System functions and manipulation of files:
browse() put up a file requester
glob() expand wildcards
globpath() expand wildcards in a number of directories
resolve() find out where a shortcut points to
fnamemodify() modify a file name
executable() check if an executable program exists
filereadable() check if a file can be read
isdirectory() check if a directory exists
getcwd() get the current working directory
getfsize() get the size of a file
getftime() get last modification time of a file
localtime() get current time
strftime() convert time to a string
tempname() get the name of a temporary file
delete() delete a file
rename() rename a file
system() get the result of a shell command
hostname() name of the system
Buffers, windows and the argument list:
argc() number of entries in the argument list
argidx() current position in the argument list
argv() get one entry from the argument list
bufexists() check if a buffer exists
buflisted() check if a buffer exists and is listed
bufloaded() check if a buffer exists and is loaded
bufname() get the name of a specific buffer
bufnr() get the buffer number of a specific buffer
winnr() get the window number for the current window
bufwinnr() get the window number of a specific buffer
winbufnr() get the buffer number of a specific window
getbufvar() get a variable value from a specific buffer
setbufvar() set a variable in a specific buffer
getwinvar() get a variable value from a specific window
setwinvar() set a variable in a specific buffer
Folding:
foldclosed() check for a closed fold at a specific line
foldlevel() check for the fold level at a specific line
foldtext() generate the line displayed for a closed fold
Syntax highlighting:
hlexists() check if a highlight group exists
hlID() get ID of a highlight group
synID() get syntax ID at a specific position
synIDattr() get a specific attribute of a syntax ID
synIDtrans() get translated syntax ID
History:
histadd() add an item to a history
histdel() delete an item from a history
histget() get an item from a history
histnr() get highest index of a history list
Interactive:
confirm() let the user make a choice
getchar() get a character from the user
getcharmod() get modifiers for the last typed character
input() get a line from the user
inputsecret() get a line from the user without showing it
inputdialog() get a line from the user in a dialog
Vim server:
serverlist() return the list of server names
remote_send() send command characters to a Vim server
remote_expr() evaluate an expression in a Vim server
server2client() send a reply to a client of a Vim server
remote_peek() check if there is a reply from a Vim server
remote_read() read a reply from a Vim server
foreground() move the Vim window to the foreground
remote_foreground() move the Vim server window to the foreground
Various:
mode() get current editing mode
visualmode() last visual mode used
hasmapto() check if a mapping exists
mapcheck() check if a matching mapping exists
maparg() get rhs of a mapping
exists() check if a variable, function, etc. exists
has() check if a feature is supported in Vim
cscope_connection() check if a cscope connection exists
did_filetype() check if a FileType autocommand was used
eventhandler() check if invoked by an event handler
getwinposx() X position of the GUI Vim window
getwinposy() Y position of the GUI Vim window
winheight() get height of a specific window
winwidth() get width of a specific window
libcall() call a function in an external library
libcallnr() idem, returning a number
*41.7* Defining a function Vim enables you to define your own functions. The basic function declaration begins as follows: > :function{name}({var1},{var2}, ...) :{body}:endfunction <Note:Function names must begin with a capital letter. Let's define a short function to return the smaller of two numbers. It starts with this line: > :function Min(num1, num2) This tells Vim that the function is named "Min" and it takes two arguments: "num1" and "num2". The first thing you need to do is to check to see which number is smaller: > : if a:num1 < a:num2 The special prefix "a:" tells Vim that the variable is a function argument. Let's assign the variable smaller the value of the smallest number: > : if a:num1 < a:num2 : let smaller = a:num1 : else : let smaller = a:num2 : endif The variable "smaller" is a local variable. Variables used inside a function are local unless prefixed by something like "g:", "a:", or "s:".Note:To access a global variable from inside a function you must prepend "g:" to it. Thus "g:count" inside a function is used for the global variable "count", and "count" is another variable, local to the function. You now use the ":return" statement to return the smallest number to the user. Finally, you end the function: > : return smaller :endfunction The complete function definition is as follows: > :function Min(num1, num2) : if a:num1 < a:num2 : let smaller = a:num1 : else : let smaller = a:num2 : endif : return smaller :endfunction A user defined function is called in exactly the same way as a builtin function. Only the name is different. The Min function can be used like this: > :echo Min(5, 8) Only now will the function be executed and the lines be interpreted by Vim. If there are mistakes, like using an undefined variable or function, you will now get an error message. When defining the function these errors are not detected. When a function reaches ":endfunction" or ":return" is used without an argument, the function returns zero. To redefine a function that already exists, use the ! for the ":function" command: > :function! Min(num1, num2, num3) USING A RANGE The ":call" command can be given a line range. This can have one of two meanings. When a function has been defined with the "range" keyword, it will take care of the line range itself. The function will be passed the variables "a:firstline" and "a:lastline". These will have the line numbers from the range the function was called with. Example: > :function Count_words() range : let n = a:firstline : let count = 0 : while n <= a:lastline : let count = count + Wordcount(getline(n)) : endwhile : echo "found " . count . " words" :endfunction You can call this function with: > :10,30call Count_words() It will be executed once and echo the number of words. The other way to use a line range is by defining a function without the "range" keyword. The function will be called once for every line in the range, with the cursor in that line. Example: > :function Number() : echo "line " . line(".") . " contains: " . getline(".") :endfunction If you call this function with: > :10,15call Number() The function will be called six times. VARIABLE NUMBER OF ARGUMENTS Vim enables you to define functions that have a variable number of arguments. The following command, for instance, defines a function that must have 1 argument (start) and can have up to 20 additional arguments: > :function Show(start, ...) The variable "a:1" contains the first optional argument, "a:2" the second, and so on. The variable "a:0" contains the number of extra arguments. For example: > :function Show(start, ...) : echohl Title : echo "Show is " . a:start : echohl None : let index = 1 : while index <= a:0 : execute 'echon " Arg " . index . " is " . a:' . index : let index = index + 1 : endwhile : echo "" :endfunction This uses the ":echohl" command to specify the highlighting used for the following ":echo" command. ":echohl None" stops it again. The ":echon" command works like ":echo", but doesn't output a line break. LISTING FUNCTIONS The ":function" command lists the names and arguments of all user-defined functions: > :function< function Show(start, ...)function GetVimIndent()function SetSyn(name)To see what a function does, use its name as an argument for ":function": > :function Show< 1 : echo "Show is " . a:start2 : let index = 13 : while index <= a:04 : execute 'echo "Arg " . index . " is " . a:' . index5 : let index = index + 16 : endwhileendfunctionDEBUGGING The line number is useful for when you get an error message or when debugging. See |debug-scripts| about debugging mode. You can also set the 'verbose' option to 12 or higher to see all function calls. Set it to 15 or higher to see every executed line. DELETING A FUNCTION To delete the Show() function: > :delfunction Show You get an error when the function doesn't exist.
*41.8* Various remarks Here is a summary of items that apply to Vim scripts. They are also mentioned elsewhere, but form a nice checklist. The end-of-line character depends on the system. For Unix a single<NL>character is used. For MS-DOS, Windows, OS/2 and the like,<CR><LF>is used. This is important when using mappings that end in a<CR>. See |:source_crnl|. WHITE SPACE Blank lines are allowed and ignored. Leading whitespace characters (blanks and TABs) are always ignored. The whitespaces between parameters (e.g. between the 'set' and the 'cpoptions' in the example below) are reduced to one blank character and plays the role of a separator, the whitespaces after the last (visible) character may or may not be ignored depending on the situation, see below. For a ":set" command involving the "=" (equal) sign, such as in: > :set cpoptions =aABceFst The whitespace immediately before the "=" sign is ignored. But there can be no whitespace after the "=" sign! To include a whitespace character in the value of an option, it must be escaped by a "\" (backslash) as in the following example: > :set tags=my\ nice\ file The same example written as > :set tags=my nice file will issue an error, because it is interpreted as: > :set tags=my :set nice :set file COMMENTS The character " (the double quote mark) starts a comment. Everything after and including this character until the end-of-line is considered a comment and is ignored, except for commands that don't consider comments, as shown in examples below. A comment can start on any character position on the line. There is a little "catch" with comments for some commands. Examples: > :abbrev dev development " shorthand :map<F3>o#include " insert include :execute cmd " do it :!ls *.c " list C files The abbreviation 'dev' will be expanded to 'development " shorthand'. The mapping of<F3>will actually be the whole line after the 'o# ....' including the '" insert include'. The "execute" command will give an error. The "!" command will send everything after it to the shell, causing an error for an unmatched '"' character. There can be no comment after ":map", ":abbreviate", ":execute" and "!" commands (there are a few more commands with this restriction). For the "map", ":abbreviate" and "execute" commands there is a trick: > :abbrev dev development|" shorthand :map<F3>o#include|" insert include :execute cmd |" do it With the '|' character the command is separated from the next one. And that next command is only a comment. Notice that there is no white space before the '|' in the abbreviation and mapping. For these commands, any character until the end-of-line or '|' is included. As a consequence of this behavior, you don't always see that trailing whitespace is included: > :map<F4>o#include To avoid these problems, you can set the 'list' option when editing vimrc files. PITFALLS Even bigger problem arises in the following example: > :map ,ab o#include :unmap ,ab Here the unmap command will not work, because it tries to unmap ",ab ". This does not exist as a mapped sequence. An error will be issued, which is very hard to identify, because the ending whitespace character on the 'unmap ,ab ' is not visible. And this is the same as what happens when one uses a comment after an 'unmap' command: > :unmap ,ab " comment Here the comment part will be ignored. However, Vim will try to unmap ',ab ', which does not exist. Rewreite it as: > :unmap ,ab|" comment RESTORING THE VIEW Sometimes you want to make a change and go back to where cursor was. Restoring the relative position would also be nice, so that the same line appears at the top of the window. This example yanks the current line, puts it above the first line in the file and then restores the view: > map ,p ma"aYHmbgg"aP`bzt`a What this does: > ma"aYHmbgg"aP`bzt`a < ma set mark a at cursor position "aY yank current line into register a Hmb go to top line in window and set mark b there gg go to first line in file "aP put the yanked line above it `b go back to top line in display zt position the text in the window as before `a go back to saved cursor position PACKAGING To avoid your function names to interfere with functions that you get from others, use this scheme: - Prepend a unique string before each function name. I often use an abbreviation. For example, "OW_" is used for the option window functions. - Put the definition of your functions together in a file. Set a global variable to indicate that the functions have been loaded. When sourcing the file again, first unload the functions. Example: > " This is the XXX package if exists("XXX_loaded") delfun XXX_one delfun XXX_two endif function XXX_one(a) ... body of function ... endfun function XXX_two(b) ... body of function ... endfun let XXX_loaded = 1
*41.9* Writing a plugin *write-plugin* You can write a Vim script in such a way that many people can use it. This is called a plugin. Vim users can drop your script in their plugin directory and use its features right away |add-plugin|. There are actually two types of plugins: global plugins: For all types of files. filetype plugins: Only for files of a specific type. In this section the first type is explained. Most items are also relevant for writing filetype plugins. The specifics for filetype plugins are in the next section |write-filetype-plugin|. NAME First of all you must choose a name for your plugin. The features provided by the plugin should be clear from its name. And it should be unlikely that someone else writes a plugin with the same name but which does something different. And please limit the name to 8 characters, to avoid problems on old Windows systems. A script that corrects typing mistakes could be called "typecorr.vim". We will use it here as an example. For the plugin to work for everybody, it should follow a few guidelines. This will be explained step-by-step. The complete example plugin is at the end. BODY Let's start with the body of the plugin, the lines that do the actual work: > 13 iabbrev teh the 14 iabbrev otehr other 15 iabbrev wnat want 16 iabbrev synchronisation 17 \ synchronization 18 let s:count = 4 The actual list should be much longer, of course. The line numbers have only been added to explain a few things, don't put them in your plugin file! HEADER You will probably add new corrections to the plugin and soon have several versions laying around. And when distributing this file, people will want to know who wrote this wonderful plugin and where they can send remarks. Therefore, put a header at the top of your plugin: > 1 " Vim global plugin for correcting typing mistakes 2 " Last Change: 2000 Oct 15 3 " Maintainer: Bram Moolenaar<Bram@vim.org>LINE CONTINUATION, AVOIDING SIDE EFFECTS In line 17 above, the line-continuation mechanism is used |line-continuation|. Users with 'compatible' set will run into trouble here, they will get an error message. We can't just reset 'compatible', because that has a lot of side effects. To avoid this, we will set the 'cpoptions' option to its Vim default value and restore it later. That will allow the use of line-continuation and make the script work for most people. It is done like this: > 10 let s:save_cpo = &cpo 11 set cpo&vim .. 41 let &cpo = s:save_cpo We first store the old value of 'cpoptions' in the s:save_cpo variable. At the end of the plugin this value is restored. Notice that a script-local variable is used |s:var|. A global variable could already be in use for something else. Always use script-local variables for things that are only used in the script. NOT LOADING It's possible that a user doesn't always want to load this plugin. Or the system administrator has dropped it in the system-wide plugin directory, but a user has his own plugin he wants to use. Then the user must have a chance to disable loading this specific plugin. This will make it possible: > 5 if exists("loaded_typecorr") 6 finish 7 endif 8 let loaded_typecorr = 1 This also avoids that when the script is loaded twice it would cause error messages for redefining functions and cause trouble for autocommands that are added twice. MAPPING Now let's make the plugin more interesting: We will add a mapping that adds a correction for the word under the cursor. We could just pick a key sequence for this mapping, but the user might already use it for something else. To allow the user to define which keys a mapping in a plugin uses, the<Leader>item can be used: > 21 map<unique><Leader>a<Plug>TypecorrAdd The "<Plug>TypecorrAdd" thing will do the work, more about that further on. The user can set the "mapleader" variable to the key sequence that he wants this mapping to start with. Thus if the user has done: > let mapleader = "_" the mapping will define "_a". If the user didn't do this, the default value will be used, which is a backslash. Then a map for "\a" will be defined.Notethat<unique>is used, this will cause an error message if the mapping already happened to exist. |:map-<unique>| But what if the user wants to define his own key sequence? We can allow that with this mechanism: > 20 if !hasmapto('<Plug>TypecorrAdd') 21 map<unique><Leader>a<Plug>TypecorrAdd 22 endif This checks if a mapping to "<Plug>TypecorrAdd" already exists, and only defines the mapping from "<Leader>a" if it doesn't. The user then has a chance of putting this in his vimrc file: > map ,c<Plug>TypecorrAdd Then the mapped key sequence will be ",c" instead of "_a" or "\a". PIECES If a script gets longer, you often want to break up the work in pieces. You can use functions or mappings for this. But you don't want these functions and mappings to interfere with the ones from other scripts. For example, you could define a function Add(), but another script could try to define the same function. To avoid this, we define the function local to the script by prepending it with "s:". We will define a function that adds a new typing correction: > 29 function s:Add(from, correct) 30 let to = input("type the correction for " . a:from . ": ") 31 exe ":iabbrev " . a:from . " " . to .. 35 endfunction Now we can call the function s:Add() from within this script. If another script also defines s:Add(), it will be local to that script and can only be called from the script it was defined in. There can also be a global Add() function (without the "s:"), which is again another function.<SID>can be used with mappings. It generates a script ID, which identifies the current script. In our typing correction plugin we use it like this: > 23 noremap<unique><script><Plug>TypecorrAdd<SID>Add .. 27 noremap<SID>Add :call<SID>Add(expand("<cword>"), 1)<CR>Thus when a user types "\a", this sequence is invoked: > \a -><Plug>TypecorrAdd -><SID>Add -> :call<SID>Add() If another script would also map<SID>Add, it would get another script ID and thus define another mapping.Notethat instead of s:Add() we use<SID>Add() here. That is because the mapping is typed by the user, thus outside of the script. The<SID>is translated to the script ID, so that Vim knows in which script to look for the Add() function. This is a bit complicated, but it's required for the plugin to work together with other plugins. The basic rule is that you use<SID>Add() in mappings and s:Add() in other places (the script itself, autocommands, user commands). We can also add a menu entry to do the same as the mapping: > 25 noremenu<script>Plugin.Add\ Correction<SID>Add The "Plugin" menu is recommended for adding menu items for plugins. In this case only one item is used. When adding more items, creating a submenu is recommended. For example, "Plugin.CVS" could be used for a plugin that offers CVS operations "Plugin.CVS.checkin", "Plugin.CVS.checkout", etc.Notethat in line 27 ":noremap" is used to avoid that any other mappings cause trouble. Someone may have remapped ":call", for example. In line 23 we also use ":noremap", but we do want "<SID>Add" to be remapped. This is why "<script>" is used here. This only allows mappings which are local to the script. |:map-<script>| The same is done in line 25 for ":noremenu". |:menu-<script>|<SID>AND<Plug>Both<SID>and<Plug>are used to avoid that mappings of typed keys interfere with mappings that are only to be used from other mappings.Notethe difference between using<SID>and<Plug>:<Plug>is visible outside of the script. It is used for mappings which the user might want to map a key sequence to.<Plug>is a special code that a typed key will never produce. To make it very unlikely that other plugins use the same sequence of characters, use this structure:<Plug>scriptname mapname In our example the scriptname is "Typecorr" and the mapname is "Add". This results in "<Plug>TypecorrAdd". Only the first character of scriptname and mapname is uppercase, so that we can see where mapname starts.<SID>is the script ID, a unique identifier for a script. Internally Vim translates<SID>to "<SNR>123_", where "123" can be any number. Thus a function "<SID>Add()" will have a name "<SNR>11_Add()" in one script, and "<SNR>22_Add()" in another. You can see this if you use the ":function" command to get a list of functions. The translation of<SID>in mappings is exactly the same, that's how you can call a script-local function from a mapping. USER COMMAND Now let's add a user command to add a correction: > 37 if !exists(":Correct") 38 command -nargs=1 Correct :call s:Add(<q-args>, 0) 39 endif The user command is defined only if no command with the same name already exists. Otherwise we would get an error here. Overriding the existing user command with ":command!" is not a good idea, this would probably make the user wonder why the command he defined himself doesn't work. |:command| SCRIPT VARIABLES When a variable starts with "s:" it is a script variable. It can only be used inside a script. Outside the script it's not visible This avoids trouble with using the same variable name in different scripts. The variables will be kept as long as Vim is running. And the same variables are used when sourcing the same script again. |s:var| The fun is that these variables can also be used in functions, autocommands and user commands that are defined in the script. In our example we can add a few lines to count the number of corrections: > 18 let s:count = 4 .. 29 function s:Add(from, correct) .. 33 let s:count = s:count + 1 34 echo s:count . " corrections now" 35 endfunction First s:count is initialized to 4 in the script itself. When later the s:Add() function is called, it increments s:count. It doesn't matter from where the function was called, since it has been defined in the script, it will use the local variables from this script. THE RESULT Here is the resulting complete example: > 1 " Vim global plugin for correcting typing mistakes 2 " Last Change: 2000 Oct 15 3 " Maintainer: Bram Moolenaar<Bram@vim.org>4 5 if exists("loaded_typecorr") 6 finish 7 endif 8 let loaded_typecorr = 1 9 10 let s:save_cpo = &cpo 11 set cpo&vim 12 13 iabbrev teh the 14 iabbrev otehr other 15 iabbrev wnat want 16 iabbrev synchronisation 17 \ synchronization 18 let s:count = 4 19 20 if !hasmapto('<Plug>TypecorrAdd') 21 map<unique><Leader>a<Plug>TypecorrAdd 22 endif 23 noremap<unique><script><Plug>TypecorrAdd<SID>Add 24 25 noremenu<script>Plugin.Add\ Correction<SID>Add 26 27 noremap<SID>Add :call<SID>Add(expand("<cword>"), 1)<CR>28 29 function s:Add(from, correct) 30 let to = input("type the correction for " . a:from . ": ") 31 exe ":iabbrev " . a:from . " " . to 32 if a:correct |exe "normal viws\<C-R>\" \b\e"| endif 33 let s:count = s:count + 1 34 echo s:count . " corrections now" 35 endfunction 36 37 if !exists(":Correct") 38 command -nargs=1 Correct :call s:Add(<q-args>, 0) 39 endif 40 41 let &cpo = s:save_cpo Line 32 wasn't explained yet. It applies the new correction to the word under the cursor. The |:normal| command is used to use the new abbreviation.Notethat mappings and abbreviations are expanded here, even though the function was called from a mapping defined with ":noremap". DOCUMENTATION *write-local-help* It's a good idea to also write some documentation for your plugin. Especially when its behavior can be changed by the user. See |add-local-help| for how they are installed. Here is a simple example for a plugin help file, called "typecorr.txt": > 1 *typecorr.txt* Plugin for correcting typing mistakes 2 3 If you make typing mistakes, this plugin will have them corrected 4 automatically. 5 6 There are currently only a few corrections. Add your own if you like. 7 8 Mappings: 9<Leader>a or<Plug>TypecorrAdd 10 Add a correction for the word under the cursor. 11 12 Commands: 13 :Correct{word}14 Add a correction for{word}. 15 16 *typecorr-settings* 17 This plugin doesn't have any settings. The first line is actually the only one for which the format matters. It will be extracted from the help file to be put in the "LOCAL ADDITIONS:" section of help.txt. The first "*" must be in the first column of the first line. You can add more tags inside ** in your help file. But be careful not to use existing help tags. You would probably use the name of your plugin in most of them, like "typecorr-settings" in the example. Using references to other parts of the help in || is recommended. This makes it easy for the user to find associated help. SUMMARY *plugin-special* Summary of special things to use in a plugin: s:name Variables local to the script.<SID>Script-ID, used for mappings and functions local to the script. hasmapto() Function to test if the user already defined a mapping for functionality the script offers.<Leader>Value of "mapleader", which the user defines as the keys that plugin mappings start with. :map<unique>Give a warning if a mapping already exists. :noremap<script>Use only mappings local to the script, not global mappings. exists(":Cmd") Check if a user command already exists.
*41.10* Writing a filetype plugin *write-filetype-plugin* *ftplugin*
A filetype plugin is like a global plugin, except that it sets options and
defines mappings for the current buffer only. See |add-filetype-plugin| for
how this type of plugin is used.
First read the section on global plugins above |41.9|. All that is said there
also applies to filetype plugins. There are a few extras, which are explained
here. The essential thing is that a filetype plugin should only have an
effect on the current buffer.
DISABLING
If you are writing a filetype plugin to be used by many people, they need a
chance to disable loading it. Put this at the top of the plugin: >
" Only do this when not done yet for this buffer
if exists("b:did_ftplugin")
finish
endif
let b:did_ftplugin = 1
This also needs to be used to avoid that the same plugin is executed twice for
the same buffer (happens when using an ":edit" command without arguments).
Now users can disable loading the default plugin completely by making a filetype
plugin with only this line: >
let b:did_ftplugin = 1
This does require that the filetype plugin directory comes before $VIMRUNTIME
in 'runtimepath'!
If you do want to use the default plugin, but overrule one of the settings,
you can make a filetype plugin like this: >
source $VIMRUNTIME/ftplugin/vim.vim
set textwidth=70
This first loads the default filetype plugin to get all its settings. Then
the value for the 'textwidth' option is changed to "70". Note that the
default plugin will have set "b:did_ftplugin", thus when it's sourced later,
it won't do anything.
OPTIONS
To make sure the filetype plugin only affects the current buffer use the >
:setlocal
command to set options. And only set options which are local to a buffer (see
the help for the option to check that). When using |:setlocal| for global
options or options local to a window, the value will change for many buffers,
and that is not what a filetype plugin should do.
When an option has a value that is a list of flags or items, consider using
"+=" and "-=" to keep the existing value. Be aware that the user may have
changed an option value already. First resetting to the default value and
then changing it often a good idea. Example: >
:setlocal formatoptions& formatoptions+=ro
MAPPINGS
To make sure mappings will only work in the current buffer use the >
:map <buffer>
command. This needs to be combined with the two-step mapping explained above.
An example of how to define funcionality in a filetype plugin: >
if !hasmapto('<Plug>JavaImport')
map <buffer> <unique> <LocalLeader>i <Plug>JavaImport
endif
noremap <buffer> <unique> <Plug>JavaImport oimport ""<Left><Esc>
|hasmapto()| is used to check if the user has already defined a map to
<Plug>JavaImport. If not, then the filetype plugin defines the default
mapping. This starts with |<LocalLeader>|, which allows the user to select
the key(s) he wants filetype plugin mappings to start with. The default is a
backslash.
"<unique>" is used to give an error message if the mapping already exists or
overlaps with an existing mapping.
|:noremap| is used to avoid that any other mappings that the user has defined
interferes. You might want to use ":noremap <script>" to allow remapping
mappings defined in this script that start with <SID>.
The user must have a chance to disable the mappings in a filetype plugin,
without disabling everything. Here is an example of how this is done for a
plugin for the mail filetype: >
" Add mappings, unless the user didn't want this.
if !exists("no_plugin_maps") && !exists("no_mail_maps")
" Quote text by inserting "> "
if !hasmapto('<Plug>MailQuote')
vmap <buffer> <LocalLeader>q <Plug>MailQuote
nmap <buffer> <LocalLeader>q <Plug>MailQuote
endif
vnoremap <buffer> <Plug>MailQuote :s/^/> /<CR>
nnoremap <buffer> <Plug>MailQuote :.,$s/^/> /<CR>
endif
Two global variables are used:
no_plugin_maps disables mappings for all filetype plugins
no_mail_maps disables mappings for a specific filetype
USER COMMANDS
To add a user command for a specific file type, so that it can only be used in
one buffer, use the "-buffer" argument to |:command|. Example: >
:command -buffer Make make %:r.s
VARIABLES
A filetype plugin will be sourced for each buffer of the type it's for. Local
script variables |s:var| will be shared between all invocations. Use local
buffer variables |b:var| if you want a variable specifically for one buffer.
FUNCTIONS
When defining a function, this only needs to be done once. But the filetype
plugin will be sourced every time a file with this filetype will be opened.
This construct make sure the function is only defined once: >
:if !exists("*s:Func")
: function s:Func(arg)
: ...
: endfunction
:endif
<
SUMMARY *ftplugin-special*
Summary of special things to use in a filetype plugin:
<LocalLeader> Value of "maplocalleader", which the user defines as
the keys that filetype plugin mappings start with.
:map <buffer> Define a mapping local to the buffer.
:noremap <script> Only remap mappings defined in this script that start
with <SID>.
:setlocal Set an option for the current buffer only.
:command -buffer Define a user command local to the buffer.
exists("*s:Func") Check if a function was already defined.
Also see |plugin-special|, the special things used for all plugins.
*41.11* Writing a compiler plugin *write-compiler-plugin*
A compiler plugin sets options for use with a specific compiler. The user can
load it with the |:compiler| command. The main use is to set the
'errorformat' and 'makeprg' options.
The only special item about these files is a mechanism to allow a user to
overrule or add to the default file. The default files start with: >
:if exists("current_compiler")
: finish
:endif
:let current_compiler = "mine"
When you write a compiler file and put it in your personal runtime directory
(e.g., ~/.vim/runtime/compiler for Unix), you set the "current_compiler"
variable to make the default file skip the settings.
When you write a compiler plugin for the Vim distribution or for a system-wide
runtime directory, use the mechanism mentioned above. When
"current_compiler" was already set by a user plugin nothing will be done.
When you write a compiler plugin to overrule settings from a default plugin,
don't check "current_compiler". This plugin is supposed to be loaded
last, thus it should be in a directory at the end of 'runtimepath'. For Unix
that could be ~/.vim/runtime/after/compiler.
Next chapter: |usr_42| Add new menus Copyright: see |manual-copyright| vim:tw=78:ts=8:ft=help:norl:
Generated by vim2html on Wed Aug 21 20:50:24 EDT 2002