[원문] http://vimdoc.sourceforge.net/htmldoc/usr_41.html
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| Lists and Dictionaries
|41.9| Exceptions
|41.10| Various remarks
|41.11| Writing a plugin
|41.12| Writing a filetype plugin
|41.13| Writing a compiler plugin
|41.14| Writing a plugin that loads quickly
|41.15| Writing library scripts
|41.16| Distributing Vim scripts
Next chapter: |usr_42.txt| Add new menus
Previous chapter: |usr_40.txt| Make new commands
Table of contents: |usr_toc.txt|
==============================================================================
*41.1* Introduction *vim-script-intro* *script*
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 += 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.
Note:
You can try out the examples by yanking the lines from the text here
and executing them with :@"
The output of the example code is:
count is 1
count is 2
count is 3
count is 4
In the first line 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.
Note:
If you happen to write a while loop that keeps on running, you can
interrupt it by pressing CTRL-C (CTRL-Break on MS-Windows).
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 1
Then there is the ":let i += 1" command. This does the same thing as
":let i = i + 1". This adds one to the variable i and assigns the new value
to the same variable.
The example was given to explain the commands, but would you really want to
make such a loop it can be written much more compact:
:for i in range(1, 4)
: echo "count is" i
:endfor
We won't explain how |:for| and |range()| work until later. Follow the links
if you are impatient.
THREE KINDS OF NUMBERS
Numbers can be decimal, hexadecimal or octal. A hexadecimal number starts
with "0x" or "0X". For example "0x1f" is decimal 31. An octal number starts
with a zero. "017" is decimal 15. Careful: don't put a zero before a decimal
number, it will be interpreted as an octal number!
The ":echo" command always prints decimal numbers. Example:
:echo 0x7f 036
127 30
A number is made negative with a minus sign. This also works for hexadecimal
and octal numbers. A minus sign is also used for subtraction. Compare this
with the previous example:
:echo 0x7f -036
97
White 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 above, 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_underscores
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 += 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. Zero is false.
Note:
Vim automatically converts a string to a number when it is looking for
a number. When using a string that doesn't start with a digit the
resulting number is zero. Thus look out for this:
:if "true"
The "true" will be interpreted as a zero, thus as 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 basic types of variables that Vim supports.
The type is dynamic, it is set each time when assigning a value to the
variable with ":let". More about types in |41.8|.
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 as they are. Only the
single quote itself is special: you need to use two to get one. A backslash
is taken literally, 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" $HOME
:if @a > 5
The &name form can be used to save an option value, set it to a new value,
do something and restore the old value. Example:
:let save_ic = &ic
:set noic
:/The Start/,$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. (Another way to do
this would be to add "\C" to the pattern, see |/\C|.)
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
20
Grouping is done with parentheses. No surprises here. Example:
:echo (10 + 5) * 2
30
Strings can be concatenated with ".". Example:
:echo "foo" . "bar"
foobar
When 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 small
The 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 >= 700
: 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 has 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"
:endif
:if str !~ '\.$'
: echo "str does not end in a full stop"
:endif
Notice the use of a single-quote string for the pattern. This is useful,
because backslashes would 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.
Even more looping can be done with the ":for" command, see below in |41.8|.
==============================================================================
*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.
If you don't want to execute a string but evaluate it to get its expression
value, you can use the eval() function:
:let optname = "path"
:let optval = eval('&' . optname)
A "&" character is prepended to "path", thus the argument to eval() is
"&path". The result will then be the value of the 'path' option.
The same thing can be done with:
:exe 'let optval = &' . optname
==============================================================================
*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 parentheses 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 buffer. Its argument
is a specification of the line number. In this case "." is used, which means
the line where the cursor is.
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: *string-functions*
nr2char() get a character by its ASCII value
char2nr() get ASCII value of a character
str2nr() convert a string to a Number
str2float() convert a string to a Float
printf() format a string according to % items
escape() escape characters in a string with a '\'
shellescape() escape a string for use with a shell command
fnameescape() escape a file name for use with a Vim command
tr() translate characters from one set to another
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
matchlist() like matchstr() and also return submatches
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
iconv() convert text from one encoding to another
byteidx() byte index of a character in a string
repeat() repeat a string multiple times
eval() evaluate a string expression
List manipulation: *list-functions*
get() get an item without error for wrong index
len() number of items in a List
empty() check if List is empty
insert() insert an item somewhere in a List
add() append an item to a List
extend() append a List to a List
remove() remove one or more items from a List
copy() make a shallow copy of a List
deepcopy() make a full copy of a List
filter() remove selected items from a List
map() change each List item
sort() sort a List
reverse() reverse the order of a List
split() split a String into a List
join() join List items into a String
range() return a List with a sequence of numbers
string() String representation of a List
call() call a function with List as arguments
index() index of a value in a List
max() maximum value in a List
min() minimum value in a List
count() count number of times a value appears in a List
repeat() repeat a List multiple times
Dictionary manipulation: *dict-functions*
get() get an entry without an error for a wrong key
len() number of entries in a Dictionary
has_key() check whether a key appears in a Dictionary
empty() check if Dictionary is empty
remove() remove an entry from a Dictionary
extend() add entries from one Dictionary to another
filter() remove selected entries from a Dictionary
map() change each Dictionary entry
keys() get List of Dictionary keys
values() get List of Dictionary values
items() get List of Dictionary key-value pairs
copy() make a shallow copy of a Dictionary
deepcopy() make a full copy of a Dictionary
string() String representation of a Dictionary
max() maximum value in a Dictionary
min() minimum value in a Dictionary
count() count number of times a value appears
Floating point computation: *float-functions*
float2nr() convert Float to Number
abs() absolute value (also works for Number)
round() round off
ceil() round up
floor() round down
trunc() remove value after decimal point
log10() logarithm to base 10
pow() value of x to the exponent y
sqrt() square root
sin() sine
cos() cosine
tan() tangent
asin() arc sine
acos() arc cosine
atan() arc tangent
atan2() arc tangent
sinh() hyperbolic sine
cosh() hyperbolic cosine
tanh() hyperbolic tangent
Variables: *var-functions*
type() type of a variable
islocked() check if a variable is locked
function() get a Funcref for a function name
getbufvar() get a variable value from a specific buffer
setbufvar() set a variable in a specific buffer
getwinvar() get a variable from specific window
gettabvar() get a variable from specific tab page
gettabwinvar() get a variable from specific window & tab page
setwinvar() set a variable in a specific window
settabvar() set a variable in a specific tab page
settabwinvar() set a variable in a specific window & tab page
garbagecollect() possibly free memory
Cursor and mark position: *cursor-functions* *mark-functions*
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
cursor() position the cursor at a line/column
getpos() get position of cursor, mark, etc.
setpos() set position of cursor, mark, etc.
byte2line() get line number at a specific byte count
line2byte() byte count at a specific line
diff_filler() get the number of filler lines above a line
Working with text in the current buffer: *text-functions*
getline() get a line or list of lines from the buffer
setline() replace a line in the buffer
append() append line or list of lines in the buffer
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
searchpos() find a match for a pattern
searchpair() find the other end of a start/skip/end
searchpairpos() find the other end of a start/skip/end
searchdecl() search for the declaration of a name
*system-functions* *file-functions*
System functions and manipulation of files:
glob() expand wildcards
globpath() expand wildcards in a number of directories
findfile() find a file in a list of directories
finddir() find a directory in a list of directories
resolve() find out where a shortcut points to
fnamemodify() modify a file name
pathshorten() shorten directory names in a path
simplify() simplify a path without changing its meaning
executable() check if an executable program exists
filereadable() check if a file can be read
filewritable() check if a file can be written to
getfperm() get the permissions of a file
getftype() get the kind of a file
isdirectory() check if a directory exists
getfsize() get the size of a file
getcwd() get the current working directory
haslocaldir() check if current window used |:lcd|
tempname() get the name of a temporary file
mkdir() create a new directory
delete() delete a file
rename() rename a file
system() get the result of a shell command
hostname() name of the system
readfile() read a file into a List of lines
writefile() write a List of lines into a file
Date and Time: *date-functions* *time-functions*
getftime() get last modification time of a file
localtime() get current time in seconds
strftime() convert time to a string
reltime() get the current or elapsed time accurately
reltimestr() convert reltime() result to a string
*buffer-functions* *window-functions* *arg-functions*
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
tabpagebuflist() return List of buffers in a tab page
tabpagenr() get the number of a tab page
tabpagewinnr() like winnr() for a specified tab page
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
getbufline() get a list of lines from the specified buffer
Command line: *command-line-functions*
getcmdline() get the current command line
getcmdpos() get position of the cursor in the command line
setcmdpos() set position of the cursor in the command line
getcmdtype() return the current command-line type
Quickfix and location lists: *quickfix-functions*
getqflist() list of quickfix errors
setqflist() modify a quickfix list
getloclist() list of location list items
setloclist() modify a location list
Insert mode completion: *completion-functions*
complete() set found matches
complete_add() add to found matches
complete_check() check if completion should be aborted
pumvisible() check if the popup menu is displayed
Folding: *folding-functions*
foldclosed() check for a closed fold at a specific line
foldclosedend() like foldclosed() but return the last line
foldlevel() check for the fold level at a specific line
foldtext() generate the line displayed for a closed fold
foldtextresult() get the text displayed for a closed fold
Syntax and highlighting: *syntax-functions* *highlighting-functions*
clearmatches() clear all matches defined by |matchadd()| and
the |:match| commands
getmatches() get all matches defined by |matchadd()| and
the |:match| commands
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
synstack() get list of syntax IDs at a specific position
synconcealed() get info about concealing
diff_hlID() get highlight ID for diff mode at a position
matchadd() define a pattern to highlight (a "match")
matcharg() get info about |:match| arguments
matchdelete() delete a match defined by |matchadd()| or a
|:match| command
setmatches() restore a list of matches saved by
|getmatches()|
Spelling: *spell-functions*
spellbadword() locate badly spelled word at or after cursor
spellsuggest() return suggested spelling corrections
soundfold() return the sound-a-like equivalent of a word
History: *history-functions*
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: *interactive-functions*
browse() put up a file requester
browsedir() put up a directory requester
confirm() let the user make a choice
getchar() get a character from the user
getcharmod() get modifiers for the last typed character
feedkeys() put characters in the typeahead queue
input() get a line from the user
inputlist() let the user pick an entry from a list
inputsecret() get a line from the user without showing it
inputdialog() get a line from the user in a dialog
inputsave() save and clear typeahead
inputrestore() restore typeahead
GUI: *gui-functions*
getfontname() get name of current font being used
getwinposx() X position of the GUI Vim window
getwinposy() Y position of the GUI Vim window
Vim server: *server-functions*
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
Window size and position: *window-size-functions*
winheight() get height of a specific window
winwidth() get width of a specific window
winrestcmd() return command to restore window sizes
winsaveview() get view of current window
winrestview() restore saved view of current window
Various: *various-functions*
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
changenr() return number of most recent change
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
getpid() get process ID of Vim
libcall() call a function in an external library
libcallnr() idem, returning a number
getreg() get contents of a register
getregtype() get type of a register
setreg() set contents and type of a register
taglist() get list of matching tags
tagfiles() get a list of tags files
mzeval() evaluate |MzScheme| expression
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*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:today" inside a function is used for the global
variable "today", and "today" 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
For people who like short functions, this does the same thing:
:function Min(num1, num2)
: if a:num1 < a:num2
: return a:num1
: endif
: return a:num2
:endfunction
A user defined function is called in exactly the same way as a built-in
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 rang
