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--- ---
language: Vimscript language: Vimscript
filename: learnvimscript.md filename: learnvimscript.vim
contributors: contributors:
- ["HiPhish", "http://hiphish.github.io/"] - ["HiPhish", "http://hiphish.github.io/"]
--- ---
## Introduction
Vim script (also called VimL) is the subset of Vim's ex-commands which supplies
a number of features one one would expect from a scripting language, such as
values, variables, functions or loops. Always keep in the back of your mind
that a Vim script file is just a sequence of ex-commands. It is very common for
a script to mix programming-language features and raw ex-commands.
You can run Vim script directly by entering the commands in command-mode (press
`:` to enter command-mode), or you can write them to a file (without the
leading `:`) and source it in a running Vim instance (`:source path/to/file`).
Some files are sourced automatically as part of your configuration (see `:h
startup`). This guide assumes that you are familiar with ex-commands and will
only cover the scripting. Help topics to the relevant manual sections are
included.
See `:h usr_41.txt` for the official introduction to Vim script. A comment is
anything following an unmatched `"` until the end of the line, and `|`
separates instructions (what `;` does in most other languages).
```vim ```vim
" ##############
" Introduction
" ##############
"
" Vim script (also called VimL) is the subset of Vim's ex-commands which
" supplies a number of features one one would expect from a scripting language,
" such as values, variables, functions or loops. Always keep in the back of
" your mind that a Vim script file is just a sequence of ex-commands. It is
" very common for a script to mix programming-language features and raw
" ex-commands.
"
" You can run Vim script directly by entering the commands in command-mode
" (press `:` to enter command-mode), or you can write them to a file (without
" the leading `:`) and source it in a running Vim instance (`:source
" path/to/file`). Some files are sourced automatically as part of your
" configuration (see |startup|). This guide assumes that you are familiar
" with ex-commands and will only cover the scripting. Help topics to the
" relevant manual sections are included.
"
" See |usr_41.txt| for the official introduction to Vim script. A comment is
" anything following an unmatched `"` until the end of the line, and `|`
" separates instructions (what `;` does in most other languages). References to
" the manual as surrounded with `|`, such as |help.txt|.
" This is a comment " This is a comment
" The vertical line '|' (pipe) separates commands " The vertical line '|' (pipe) separates commands
@ -51,30 +55,28 @@ echo {
\ 'a': 1, \ 'a': 1,
\ 'b': 2 \ 'b': 2
\} \}
```
## Types " #######
" Types
" #######
"
" For an overview of types see |E712|. For an overview of operators see
" |expression-syntax|
For an overview of types see `:h E712`. For an overview of operators see " Numbers (|expr-number|)
`:h expression-syntax` " #######
### Numbers
See `:h expr-number`
```vim
echo 123 |" Decimal echo 123 |" Decimal
echo 0b1111011 |" Binary echo 0b1111011 |" Binary
echo 0173 |" Octal echo 0173 |" Octal
echo 0x7B |" Hexadecimal echo 0x7B |" Hexadecimal
echo 123.0 |" Floating-point echo 123.0 |" Floating-point
echo 1.23e2 |" Floating-point (scientific notation) echo 1.23e2 |" Floating-point (scientific notation)
```
Note that an *integer* number with a leading `0` is in octal notation. The " Note that an *integer* number with a leading `0` is in octal notation. The
usual arithmetic operations are supported. " usual arithmetic operations are supported.
```vim
echo 1 + 2 |" Addition echo 1 + 2 |" Addition
echo 1 - 2 |" Subtraction echo 1 - 2 |" Subtraction
echo - 1 |" Negation (unary minus) echo - 1 |" Negation (unary minus)
@ -82,22 +84,19 @@ echo + 1 |" Unary plus (does nothing really, but still legal)
echo 1 * 2 |" Multiplication echo 1 * 2 |" Multiplication
echo 1 / 2 |" Division echo 1 / 2 |" Division
echo 1 % 2 |" Modulo (remainder) echo 1 % 2 |" Modulo (remainder)
```
### Booleans " Booleans (|Boolean|)
See `:h Boolean` " ########
"
" The number 0 is false, every other number is true. Strings are implicitly
" converted to numbers (see below). There are two pre-defined semantic
" constants.
The number 0 is false, every other number is true. Strings are implicitly
converted to numbers (see below). There are two pre-defined semantic constants.
```vim
echo v:true |" Evaluates to 1 or the string 'v:true' echo v:true |" Evaluates to 1 or the string 'v:true'
echo v:false |" Evaluates to 0 or the string 'v:false' echo v:false |" Evaluates to 0 or the string 'v:false'
```
Boolean values can result from comparison of two objects. " Boolean values can result from comparison of two objects.
```vim
echo x == y |" Equality by value echo x == y |" Equality by value
echo x != y |" Unequality echo x != y |" Unequality
echo x > y |" Greater than echo x > y |" Greater than
@ -109,7 +108,7 @@ echo x isnot y |" Instance non-identity (lists and dictionaries)
" Strings are compared based on their alphanumerical ordering " Strings are compared based on their alphanumerical ordering
" echo 'a' < 'b'. Case sensitivity depends on the setting of 'ignorecase' " echo 'a' < 'b'. Case sensitivity depends on the setting of 'ignorecase'
"
" Explicit case-sensitivity is specified by appending '#' (match case) or '?' " Explicit case-sensitivity is specified by appending '#' (match case) or '?'
" (ignore case) to the operator. Prefer explicity case sensitivity when writing " (ignore case) to the operator. Prefer explicity case sensitivity when writing
" portable scripts. " portable scripts.
@ -125,36 +124,30 @@ echo "hi" =~? "hello" |" Regular expression match, case insensitive
echo "hi" !~ "hello" |" Regular expression unmatch, use 'ignorecase' echo "hi" !~ "hello" |" Regular expression unmatch, use 'ignorecase'
echo "hi" !~# "hello" |" Regular expression unmatch, case sensitive echo "hi" !~# "hello" |" Regular expression unmatch, case sensitive
echo "hi" !~? "hello" |" Regular expression unmatch, case insensitive echo "hi" !~? "hello" |" Regular expression unmatch, case insensitive
```
Boolean operations are possible. " Boolean operations are possible.
```vim
echo v:true && v:false |" Logical AND echo v:true && v:false |" Logical AND
echo v:true || v:false |" Logical OR echo v:true || v:false |" Logical OR
echo ! v:true |" Logical NOT echo ! v:true |" Logical NOT
echo v:true ? 'yes' : 'no' |" Ternary operator echo v:true ? 'yes' : 'no' |" Ternary operator
```
### Strings " Strings (|String|)
See `:h String` " #######
"
" An ordered zero-indexed sequence of bytes. The encoding of text into bytes
" depends on the option |'encoding'|.
An ordered zero-indexed sequence of bytes. The encoding of text into bytes
depends on the option `:h 'encoding'`.
```vim
" Literal constructors " Literal constructors
echo "Hello world\n" |" The last two characters stand for newline echo "Hello world\n" |" The last two characters stand for newline
echo 'Hello world\n' |" The last two characters are literal echo 'Hello world\n' |" The last two characters are literal
echo 'Let''s go!' |" Two single quotes become one quote character echo 'Let''s go!' |" Two single quotes become one quote character
```
Single-quote strings take all characters are literal, except two single quotes, " Single-quote strings take all characters are literal, except two single
which are taken to be a single quote in the string itself. See `:h expr-quote` " quotes, which are taken to be a single quote in the string itself. See
for all possible escape sequences. " |expr-quote| for all possible escape sequences.
```
" String concatenation " String concatenation
" The .. operator is preferred, but only supported in since Vim 8.1.1114 " The .. operator is preferred, but only supported in since Vim 8.1.1114
echo 'Hello ' . 'world' |" String concatenation echo 'Hello ' . 'world' |" String concatenation
@ -172,17 +165,16 @@ echo 'Hello'[1:-2] |" Substring until second to last byte
echo 'Hello'[1:] |" Substring with starting index echo 'Hello'[1:] |" Substring with starting index
echo 'Hello'[:2] |" Substring with ending index echo 'Hello'[:2] |" Substring with ending index
echo 'Hello'[-2:] |" Substring relative to end of string echo 'Hello'[-2:] |" Substring relative to end of string
```
A negative index is relative to the end of the string. See `:h " A negative index is relative to the end of the string. See
string-functions` for all string-related functions. " |string-functions| for all string-related functions.
### Lists " Lists (|List|)
See `:h List` " #####
"
" An ordered zero-indexed heterogeneous sequence of arbitrary Vim script
" objects.
An ordered zero-indexed heterogeneous sequence of arbitrary Vim script objects.
```vim
" Literal constructor " Literal constructor
echo [] |" Empty list echo [] |" Empty list
echo [1, 2, 'Hello'] |" List with elements echo [1, 2, 'Hello'] |" List with elements
@ -192,28 +184,27 @@ echo [[1, 2], 'Hello'] |" Lists can be nested arbitrarily
" List concatenation " List concatenation
echo [1, 2] + [3, 4] |" Creates a new list echo [1, 2] + [3, 4] |" Creates a new list
" List indexing, negative is relative to end of list (:h list-index) " List indexing, negative is relative to end of list (|list-index|)
echo [1, 2, 3, 4][2] |" Third element echo [1, 2, 3, 4][2] |" Third element
echo [1, 2, 3, 4][-1] |" Last element echo [1, 2, 3, 4][-1] |" Last element
" List slicing (:h sublist) " List slicing (|sublist|)
echo [1, 2, 3, 4][:] |" Shallow copy of entire list echo [1, 2, 3, 4][:] |" Shallow copy of entire list
echo [1, 2, 3, 4][:2] |" Sublist until third item (inclusive) echo [1, 2, 3, 4][:2] |" Sublist until third item (inclusive)
echo [1, 2, 3, 4][2:] |" Sublist from third item (inclusive) echo [1, 2, 3, 4][2:] |" Sublist from third item (inclusive)
echo [1, 2, 3, 4][:-2] |" Sublist until second-to-last item (inclusive) echo [1, 2, 3, 4][:-2] |" Sublist until second-to-last item (inclusive)
```
All slicing operations create new lists. To modify a list in-place use list " All slicing operations create new lists. To modify a list in-place use list
functions (`:h list-functions`) or assign directly to an item (see below about " functions (|list-functions|) or assign directly to an item (see below about
variables). " variables).
### Dictionaries
See `:h Dictionary`
An unordered sequence of key-value pairs, keys are always strings (numbers are " Dictionaries (|Dictionary|)
implicitly converted to strings). " ############
"
" An unordered sequence of key-value pairs, keys are always strings (numbers
" are implicitly converted to strings).
```vim
" Dictionary literal " Dictionary literal
echo {} |" Empty dictionary echo {} |" Empty dictionary
echo {'a': 1, 'b': 2} |" Dictionary literal echo {'a': 1, 'b': 2} |" Dictionary literal
@ -223,61 +214,61 @@ echo {'x': {'a': 1, 'b': 2}} |" Nested dictionary
" Indexing a dictionary " Indexing a dictionary
echo {'a': 1, 'b': 2}['a'] |" Literal index echo {'a': 1, 'b': 2}['a'] |" Literal index
echo {'a': 1, 'b': 2}.a |" Syntactic sugar for simple keys echo {'a': 1, 'b': 2}.a |" Syntactic sugar for simple keys
```
See `:h dict-functions` for dictionary manipulation functions. " See |dict-functions| for dictionary manipulation functions.
### Funcref
See `:h Funcref`
Reference to a function, uses the function name as a string for construction. " Funcref (|Funcref|)
When stored in a variable the name of the variable has the same restrictions " #######
as a function name (see below). "
" Reference to a function, uses the function name as a string for construction.
" When stored in a variable the name of the variable has the same restrictions
" as a function name (see below).
```vim
echo function('type') |" Reference to function type() echo function('type') |" Reference to function type()
" Note that `funcref('type')` will throw an error because the argument must be
" a user-defined function; see further below for defining your own functions.
echo funcref('type') |" Reference by identity, not name echo funcref('type') |" Reference by identity, not name
" A lambda (|lambda|) is an anonymous function; it can only contain one
" expression in its body, which is also its implicit return value.
echo {x -> x * x} |" Anonymous function echo {x -> x * x} |" Anonymous function
echo function('substitute', ['hello']) |" Partial function echo function('substitute', ['hello']) |" Partial function
```
A lambda (`:h lambda`) is an anonymous function; it can only contain one
expression in its body, which is also its implicit return value.
### Regular expression " Regular expression (|regular-expression|)
See `:h regular-expression` " ##################
"
" A regular expression pattern is generally a string, but in some cases you can
" also use a regular expression between a pair of delimiters (usually `/`, but
" you can choose anything).
A regular expression pattern is generally a string, but in some cases you can
also use a regular expression between a pair of delimiters (usually `/`, but
you can choose anything).
```vim
" Substitute 'hello' for 'Hello' " Substitute 'hello' for 'Hello'
substitute/hello/Hello/ substitute/hello/Hello/
```
## Implicit type conversions
Strings are converted to numbers, and numbers to strings when necessary. A " ###########################
number becomes its decimal notation as a string. A string becomes its numerical " Implicit type conversions
value if it can be parsed to a number, otherwise it becomes zero. " ###########################
"
" Strings are converted to numbers, and numbers to strings when necessary. A
" number becomes its decimal notation as a string. A string becomes its
" numerical value if it can be parsed to a number, otherwise it becomes zero.
```vim
echo "1" + 1 |" Number echo "1" + 1 |" Number
echo "1" .. 1 |" String echo "1" .. 1 |" String
echo "0xA" + 1 |" Number echo "0xA" + 1 |" Number
" Strings are treated like numbers when used as booleans " Strings are treated like numbers when used as booleans
echo "true" ? 1 : 0 |" This string is parsed to 0, which is false echo "true" ? 1 : 0 |" This string is parsed to 0, which is false
```
" ###########
" Variables
" ###########
"
" Variables are bound within a scope; if no scope is provided a default is
" chosen by Vim. Use `:let` and `:const` to bind a value and `:unlet` to unbind
" it.
## Variables
Variables are bound within a scope; if no scope is provided a default is chosen
by Vim. Use `:let` and `:const` to bind a value and `:unlet` to unbind it.
```vim
let b:my_var = 1 |" Local to current buffer let b:my_var = 1 |" Local to current buffer
let w:my_var = 1 |" Local to current window let w:my_var = 1 |" Local to current window
let t:my_var = 1 |" Local to current tab page let t:my_var = 1 |" Local to current tab page
@ -287,7 +278,7 @@ let s:my_var = 1 |" Local to current script file
let a:my_arg = 1 |" Function argument (see functions below) let a:my_arg = 1 |" Function argument (see functions below)
" The Vim scope is read-only " The Vim scope is read-only
echo v:true |" Special built-in Vim variables (:h v:var) echo v:true |" Special built-in Vim variables (|v:var|)
" Access special Vim memory like variables " Access special Vim memory like variables
let @a = 'Hello' |" Register let @a = 'Hello' |" Register
@ -297,7 +288,7 @@ let &l:textwidth = 79 |" Local option
let &g:textwidth = 79 |" Global option let &g:textwidth = 79 |" Global option
" Access scopes as dictionaries (can be modified like all dictionaries) " Access scopes as dictionaries (can be modified like all dictionaries)
" See the :h dict-functions, especially get(), for access and manipulation " See the |dict-functions|, especially |get()|, for access and manipulation
echo b: |" All buffer variables echo b: |" All buffer variables
echo w: |" All window variables echo w: |" All window variables
echo t: |" All tab page variables echo t: |" All tab page variables
@ -308,33 +299,37 @@ echo a: |" All function arguments
echo v: |" All Vim variables echo v: |" All Vim variables
" Constant variables " Constant variables
const x = 10 |" See :h :const, :h :lockvar const x = 10 |" See |:const|, |:lockvar|
" Function reference variables have the same restrictions as function names " Function reference variables have the same restrictions as function names
let IsString = {x -> type(x) == type('')} |" Global: capital letter let IsString = {x -> type(x) == type('')} |" Global: capital letter
let s:isNumber = {x -> type(x) == type(0)} |" Local: any name allowed let s:isNumber = {x -> type(x) == type(0)} |" Local: any name allowed
```
When omitted the scope `g:` is implied, except in functions, there `l:` is " When omitted the scope `g:` is implied, except in functions, there `l:` is
implied. " implied.
### Multiple value binding (list unpacking)
```vim " Multiple value binding (list unpacking)
" #######################################
"
" Assign values of list to multiple variables (number of items must match) " Assign values of list to multiple variables (number of items must match)
let [x, y] = [1, 2] let [x, y] = [1, 2]
" Assign the remainer to a rest variable (note the semicolon) " Assign the remainer to a rest variable (note the semicolon)
let [mother, father; children] = ['Alice', 'Bob', 'Carol', 'Dennis', 'Emily'] let [mother, father; children] = ['Alice', 'Bob', 'Carol', 'Dennis', 'Emily']
```
## Flow control
### Conditional " ##############
" Flow control
" ##############
Conditions are set between `if` and `endif`. They can be nested. " Conditional (|:if|, |:elseif|, |:else|, |:endif|)
" ###########
"
" Conditions are set between `if` and `endif`. They can be nested.
let condition = v:true
```vim
if condition if condition
echo 'First condition' echo 'First condition'
elseif another_condition elseif another_condition
@ -342,19 +337,19 @@ elseif another_condition
else else
echo 'Fail' echo 'Fail'
endif endif
```
### Loops " Loops (|:for|, |:endfor|, |:while|, |:endwhile|, |:break|, |:continue|)
" #####
"
" Two types of loops: `:for` and `:while`. Use `:continue` to skip to the next
" iteration, `:break` to break out of the loop.
Two types of loops: `:for` and `:while`. Use `:continue` to skip to the next " For-loop (|:for|, |:endfor|)
iteration, `:break` to break out of the loop. " ========
"
" For-loops iterate over lists and nothing else. If you want to iterate over
" another sequence you need to use a function which will create a list.
#### For-loop
For-loops iterate over lists and nothing else. If you want to iterate over
another sequence you need to use a function which will create a list.
```vim
" Iterate over a list " Iterate over a list
for person in ['Alice', 'Bob', 'Carol', 'Dennis', 'Emily'] for person in ['Alice', 'Bob', 'Carol', 'Dennis', 'Emily']
echo 'Hello ' .. person echo 'Hello ' .. person
@ -384,23 +379,21 @@ endfor
for [symbol, value] in items({'π': 3.14, 'e': 2.71}) for [symbol, value] in items({'π': 3.14, 'e': 2.71})
echo 'The number ' .. symbol .. ' is approximately ' .. value echo 'The number ' .. symbol .. ' is approximately ' .. value
endfor endfor
```
#### While-loops " While-loops (|:while|, |:endwhile|)
```vim let there_yet = v:true
while !there_yet while !there_yet
echo 'Are we there yet?' echo 'Are we there yet?'
endwhile endwhile
```
### Exception handling
See `:h exception-handling`
Throw new exceptions as strings, catch them by pattern-matching a regular " Exception handling (|exception-handling|)
expression against the string " ##################
"
" Throw new exceptions as strings, catch them by pattern-matching a regular
" expression against the string
```vim
" Throw new exception " Throw new exception
throw "Wrong arguments" throw "Wrong arguments"
@ -414,14 +407,15 @@ catch /.*/
finally finally
echo 'I'm done trying' echo 'I'm done trying'
endtry endtry
```
## Functions " ##########
" Functions
" ##########
### Defining functions " Defining functions (|:function|, |:endfunction|)
" ##################
```vim
" Unscoped function names have to start with a capital letter " Unscoped function names have to start with a capital letter
function! AddNumbersLoudly(x, y) function! AddNumbersLoudly(x, y)
" Use a: scope to access arguments " Use a: scope to access arguments
@ -434,33 +428,31 @@ function! s:addNumbersLoudly(x, y)
echo 'Adding' .. a:x .. 'and' .. a:y echo 'Adding' .. a:x .. 'and' .. a:y
return a:x + a:y return a:x + a:y
endfunction endfunction
```
Without the exclamation mark it would be an error to re-define a function, with " Without the exclamation mark it would be an error to re-define a function,
the exclamation mark the new definition can replace the old one. Since Vim " with the exclamation mark the new definition can replace the old one. Since
script files can be reloaded several times over the course of a session it is " Vim script files can be reloaded several times over the course of a session
best to use the exclamation mark unless you really know what you are doing. " it is best to use the exclamation mark unless you really know what you are
" doing.
Function definitions can have special qualifiers following the argument list. " Function definitions can have special qualifiers following the argument list.
```vim
" Range functions define two implicit arguments, which will be set to the range " Range functions define two implicit arguments, which will be set to the range
" of the ex-command " of the ex-command
function! FirstAndLastLine() range function! FirstAndLastLine() range
echo [a:firstline, a:lastline] echo [a:firstline, a:lastline]
endfunction endfunction
" Prints the first and last line that match a pattern (:h cmdline-ranges) " Prints the first and last line that match a pattern (|cmdline-ranges|)
/^#!/,/!#$/call FirstAndLastLine() /^#!/,/!#$/call FirstAndLastLine()
" Aborting functions, abort once error occurs (|:func-abort|)
" Aborting functions, abort once error occurs (:h :func-abort)
function! SourceMyFile() abort function! SourceMyFile() abort
source my-file.vim |" Try sourcing non-existing file source my-file.vim |" Try sourcing non-existing file
echo 'This will never be printed' echo 'This will never be printed'
endfunction endfunction
" Closures, functions carrying values from outer scope (:h :func-closure) " Closures, functions carrying values from outer scope (|:func-closure|)
function! MakeAdder(x) function! MakeAdder(x)
function! Adder(n) closure function! Adder(n) closure
return a:n + a:x return a:n + a:x
@ -470,7 +462,7 @@ endfunction
let AddFive = MakeAdder(5) let AddFive = MakeAdder(5)
echo AddFive(3) |" Prints 8 echo AddFive(3) |" Prints 8
" Dictionary functions, poor man's OOP methods (:h Dictionary-function) " Dictionary functions, poor man's OOP methods (|Dictionary-function|)
function! Mylen() dict function! Mylen() dict
return len(self.data) |" Implicit variable self return len(self.data) |" Implicit variable self
endfunction endfunction
@ -482,11 +474,10 @@ let mydict = {'data': [0, 1, 2, 3]}
function! mydict.len() function! mydict.len()
return len(self.data) return len(self.data)
endfunction endfunction
```
### Calling functions " Calling functions (|:call|)
" #################
```vim
" Call a function for its return value, and possibly for its side effects " Call a function for its return value, and possibly for its side effects
let animals = keys({'cow': 'moo', 'dog': 'woof', 'cat': 'meow'}) let animals = keys({'cow': 'moo', 'dog': 'woof', 'cat': 'meow'})
@ -496,16 +487,13 @@ call sign_undefine()
" The call() function calls a function reference and passes parameters as a " The call() function calls a function reference and passes parameters as a
" list, and returns the function's result. " list, and returns the function's result.
echo call(function('get'), [{'a': 1, 'b': 2}, 'c', 3]) |" Prints 3 echo call(function('get'), [{'a': 1, 'b': 2}, 'c', 3]) |" Prints 3
```
Recall that Vim script is embedded within the ex-commands, that is why we " Recall that Vim script is embedded within the ex-commands, that is why we
cannot just call a function directly, we have to use the `:call` ex-command. " cannot just call a function directly, we have to use the `:call` ex-command.
### Function namespaces " Function namespaces (|write-library-script|, |autoload|)
" ###################
See `:h write-library-script`, `:h autoload`
```vim
" Must be defined in autoload/foo/bar.vim " Must be defined in autoload/foo/bar.vim
" Namspaced function names do not have to start with a capital letter " Namspaced function names do not have to start with a capital letter
function! foo#bar#log(value) function! foo#bar#log(value)
@ -513,68 +501,61 @@ function! foo#bar#log(value)
endfunction endfunction
call foo#bar#log('Hello') call foo#bar#log('Hello')
```
## Frequently used ex-commands " #############################
" Frequently used ex-commands
" #############################
### Sourcing runtime files
See `:h 'runtimepath'` " Sourcing runtime files (|'runtimepath'|)
" ######################
```vim
" Source first match among runtime paths " Source first match among runtime paths
runtime plugin/my-plugin.vim runtime plugin/my-plugin.vim
```
### Defining new ex-commands
See `:h 40.2`, `:h :command`
```vim " Defining new ex-commands (|40.2|, |:command|)
" ########################
" First argument here is the name of the command, rest is the command body " First argument here is the name of the command, rest is the command body
command! SwapAdjacentLines normal! ddp command! SwapAdjacentLines normal! ddp
```
The exclamation mark works the same as with `:function`. User-defined commands " The exclamation mark works the same as with `:function`. User-defined
must start with a capital letter. The `:command` command can take a number of " commands must start with a capital letter. The `:command` command can take a
attributes (some of which have their own parameters with `=`), such as " number of attributes (some of which have their own parameters with `=`), such
`-nargs`, all of them start with a dash to set them apart from the command " as `-nargs`, all of them start with a dash to set them apart from the command
name. " name.
```vim
:command -nargs=1 Error echoerr <args> :command -nargs=1 Error echoerr <args>
```
### Defining auto-commands
See `:h 40.3`, `:h autocmd`, `:h autocommand-events`
```vim " Defining auto-commands (|40.3|, |autocmd|, |autocommand-events|)
" ######################
" The arguments are "events", "patterns", rest is "commands" " The arguments are "events", "patterns", rest is "commands"
autocmd BufWritePost $MYVIMRC source $MYVIMRC autocmd BufWritePost $MYVIMRC source $MYVIMRC
```
Events and patterns are separated by commas with no space between. See `:h " Events and patterns are separated by commas with no space between. See
autocmd-events` for standard events, `:h User` for custom events. Everything " |autocmd-events| for standard events, |User| for custom events. Everything
else are the ex-commands which will be executed. " else are the ex-commands which will be executed.
#### Auto groups " Auto groups
" ===========
"
" When a file is sourced multiple times the auto-commands are defined anew,
" without deleting the old ones, causing auto-commands to pile up over time.
" Use auto-groups and the following ritual to guard against this.
When a file is sourced multiple times the auto-commands are defined anew,
without deleting the old ones, causing auto-commands to pile up over time. Use
auto-groups and the following ritual to guard against this.
```vim
augroup auto-source |" The name of the group is arbitrary augroup auto-source |" The name of the group is arbitrary
autocmd! |" Deletes all auto-commands in the current group autocmd! |" Deletes all auto-commands in the current group
autocmd BufWritePost $MYVIMRC source $MYVIMRC autocmd BufWritePost $MYVIMRC source $MYVIMRC
augroup END |" Switch back to default auto-group augroup END |" Switch back to default auto-group
```
It is also possible to assign a group directly. This is useful if the " It is also possible to assign a group directly. This is useful if the
definition of the group is in one script and the definition of the auto-command " definition of the group is in one script and the definition of the
is in another script. " auto-command is in another script.
```vim
" In one file " In one file
augroup auto-source augroup auto-source
autocmd! autocmd!
@ -582,35 +563,33 @@ augroup END
" In another file " In another file
autocmd auto-source BufWritePost $MYVIMRC source $MYVIMRC autocmd auto-source BufWritePost $MYVIMRC source $MYVIMRC
```
### Executing (run-time macros of sorts) " Executing (run-time macros of sorts)
" ####################################
Sometimes we need to construct an ex-command where part of the command is not " Sometimes we need to construct an ex-command where part of the command is not
known until runtime. " known until runtime.
```vim
let line = 3 |" Line number determined at runtime let line = 3 |" Line number determined at runtime
execute line .. 'delete' |" Delete a line execute line .. 'delete' |" Delete a line
```
### Executing normal-mode commands " Executing normal-mode commands
" ##############################
"
" Use `:normal` to play back a sequence of normal mode commands from the
" command-line. Add an exclamation mark to ignore user mappings.
Use `:normal` to play back a sequence of normal mode commands from the
command-line. Add an exclamation mark to ignore user mappings.
```vim
normal! ggddGp |" Transplant first line to end of buffer normal! ggddGp |" Transplant first line to end of buffer
" Window commands can be used with :normal, or with :wincmd if :normal would " Window commands can be used with :normal, or with :wincmd if :normal would
" not work " not work
wincmd L |" Move current window all the way to the right wincmd L |" Move current window all the way to the right
```
## Frequently used functions " ###########################
" Frequently used functions
" ###########################
```vim
" Feature check " Feature check
echo has('nvim') |" Running Neovim echo has('nvim') |" Running Neovim
echo has('python3') |" Support for Python 3 plugins echo has('python3') |" Support for Python 3 plugins
@ -633,7 +612,7 @@ echo exists("#BufReadPre#*.gz") |" Event and pattern
echo exists("#filetypeindent") |" Auto-command group echo exists("#filetypeindent") |" Auto-command group
echo exists("##ColorScheme") |" Auto-commnand supported for event echo exists("##ColorScheme") |" Auto-commnand supported for event
" Various dynamic values (see :h expand()) " Various dynamic values (see |expand()|)
echo expand('%') |" Current file name echo expand('%') |" Current file name
echo expand('<cword>') |" Current word under cursor echo expand('<cword>') |" Current word under cursor
echo expand('%:p') |" Modifier are possible echo expand('%:p') |" Modifier are possible
@ -647,26 +626,26 @@ echo type(my_var) == type(function('type')) |" Funcref
" Format strings " Format strings
echo printf('%d in hexadecimal is %X', 123, 123) echo printf('%d in hexadecimal is %X', 123, 123)
```
## Tricks of the trade " #####################
" Tricks of the trade
" #####################
### Source guard " Source guard
" ############
```vim
" Prevent a file from being source multiple times; users can set the variable " Prevent a file from being source multiple times; users can set the variable
" in their configuration to prevent the plugin from loading at all. " in their configuration to prevent the plugin from loading at all.
if exists('g:loaded_my_plugin') if exists('g:loaded_my_plugin')
finish finish
endif endif
let g:loaded_my_plugin = v:true let g:loaded_my_plugin = v:true
```
### Default values " Default values
" ##############
```vim
" Get a default value: if the user defines a variable use it, otherwise use a " Get a default value: if the user defines a variable use it, otherwise use a
" hard-coded default. Uses the fact that a scope is also a dictionary. " hard-coded default. Uses the fact that a scope is also a dictionary.
let s:greeting = get(g:, 'my_plugin_greeting', 'Hello') l
``` ```