path: root/runtime/doc/if_pyth.txt

*if_pyth.txt*   For Vim version 7.3.  Last change: 2013 May 25


		  VIM REFERENCE MANUAL    by Paul Moore


The Python Interface to Vim				*python* *Python*

1. Commands					|python-commands|
2. The vim module				|python-vim|
3. Buffer objects				|python-buffer|
4. Range objects				|python-range|
5. Window objects				|python-window|
6. Tab page objects				|python-tabpage|
7. vim.bindeval objects				|python-bindeval-objects|
8. pyeval(), py3eval() Vim functions		|python-pyeval|
9. Dynamic loading				|python-dynamic|
10. Python 3					|python3|

{Vi does not have any of these commands}

The Python 2.x interface is available only when Vim was compiled with the
|+python| feature.
The Python 3 interface is available only when Vim was compiled with the
|+python3| feature.

==============================================================================
1. Commands						*python-commands*

					*:python* *:py* *E205* *E263* *E264*
:[range]py[thon] {stmt}
			Execute Python statement {stmt}.  A simple check if
			the `:python` command is working: >
				:python print "Hello"

:[range]py[thon] << {endmarker}
{script}
{endmarker}
			Execute Python script {script}.
			Note: This command doesn't work when the Python
			feature wasn't compiled in.  To avoid errors, see
			|script-here|.

{endmarker} must NOT be preceded by any white space.  If {endmarker} is
omitted from after the "<<", a dot '.' must be used after {script}, like
for the |:append| and |:insert| commands.
This form of the |:python| command is mainly useful for including python code
in Vim scripts.

Example: >
	function! IcecreamInitialize()
	python << EOF
	class StrawberryIcecream:
		def __call__(self):
			print 'EAT ME'
	EOF
	endfunction
<
Note: Python is very sensitive to the indenting.  Make sure the "class" line
and "EOF" do not have any indent.

							*:pydo*
:[range]pydo {body}	Execute Python function "def _vim_pydo(line, linenr):
			{body}" for each line in the [range], with the
			function arguments being set to the text of each line
			in turn, without a trailing <EOL>, and the current
			line number. The function should return a string or
			None. If a string is returned, it becomes the text of
			the line in the current turn. The default for [range]
			is the whole file: "1,$".
			{not in Vi}

Examples:
>
	:pydo return "%s\t%d" % (line[::-1], len(line))
	:pydo if line: return "%4d: %s" % (linenr, line)
<
							*:pyfile* *:pyf*
:[range]pyf[ile] {file}
			Execute the Python script in {file}.  The whole
			argument is used as a single file name.  {not in Vi}

Both of these commands do essentially the same thing - they execute a piece of
Python code, with the "current range" |python-range| set to the given line
range.

In the case of :python, the code to execute is in the command-line.
In the case of :pyfile, the code to execute is the contents of the given file.

Python commands cannot be used in the |sandbox|.

To pass arguments you need to set sys.argv[] explicitly.  Example: >

	:python import sys
	:python sys.argv = ["foo", "bar"]
	:pyfile myscript.py

Here are some examples					*python-examples*  >

	:python from vim import *
	:python from string import upper
	:python current.line = upper(current.line)
	:python print "Hello"
	:python str = current.buffer[42]

(Note that changes - like the imports - persist from one command to the next,
just like in the Python interpreter.)

==============================================================================
2. The vim module					*python-vim*

Python code gets all of its access to vim (with one exception - see
|python-output| below) via the "vim" module.  The vim module implements two
methods, three constants, and one error object.  You need to import the vim
module before using it: >
	:python import vim

Overview >
	:py print "Hello"		# displays a message
	:py vim.command(cmd)		# execute an Ex command
	:py w = vim.windows[n]		# gets window "n"
	:py cw = vim.current.window	# gets the current window
	:py b = vim.buffers[n]		# gets buffer "n"
	:py cb = vim.current.buffer	# gets the current buffer
	:py w.height = lines		# sets the window height
	:py w.cursor = (row, col)	# sets the window cursor position
	:py pos = w.cursor		# gets a tuple (row, col)
	:py name = b.name		# gets the buffer file name
	:py line = b[n]			# gets a line from the buffer
	:py lines = b[n:m]		# gets a list of lines
	:py num = len(b)		# gets the number of lines
	:py b[n] = str			# sets a line in the buffer
	:py b[n:m] = [str1, str2, str3]	# sets a number of lines at once
	:py del b[n]			# deletes a line
	:py del b[n:m]			# deletes a number of lines


Methods of the "vim" module

vim.command(str)					*python-command*
	Executes the vim (ex-mode) command str.  Returns None.
	Examples: >
	    :py vim.command("set tw=72")
	    :py vim.command("%s/aaa/bbb/g")
<	The following definition executes Normal mode commands: >
		def normal(str):
			vim.command("normal "+str)
		# Note the use of single quotes to delimit a string containing
		# double quotes
		normal('"a2dd"aP')
<								*E659*
	The ":python" command cannot be used recursively with Python 2.2 and
	older.  This only works with Python 2.3 and later: >
	    :py vim.command("python print 'Hello again Python'")

vim.eval(str)						*python-eval*
	Evaluates the expression str using the vim internal expression
	evaluator (see |expression|).  Returns the expression result as:
	- a string if the Vim expression evaluates to a string or number
	- a list if the Vim expression evaluates to a Vim list
	- a dictionary if the Vim expression evaluates to a Vim dictionary
	Dictionaries and lists are recursively expanded.
	Examples: >
	    :py text_width = vim.eval("&tw")
	    :py str = vim.eval("12+12")		# NB result is a string! Use
						# string.atoi() to convert to
						# a number.

	    :py tagList = vim.eval('taglist("eval_expr")')
<	The latter will return a python list of python dicts, for instance:
	[{'cmd': '/^eval_expr(arg, nextcmd)$/', 'static': 0, 'name':
	'eval_expr', 'kind': 'f', 'filename': './src/eval.c'}]

vim.bindeval(str)					*python-bindeval*
	Like |python-eval|, but returns special objects described in 
	|python-bindeval-objects|. These python objects let you modify (|List| 
	or |Dictionary|) or call (|Funcref|) vim objecs.

Error object of the "vim" module

vim.error						*python-error*
	Upon encountering a Vim error, Python raises an exception of type
	vim.error.
	Example: >
		try:
			vim.command("put a")
		except vim.error:
			# nothing in register a

Constants of the "vim" module

	Note that these are not actually constants - you could reassign them.
	But this is silly, as you would then lose access to the vim objects
	to which the variables referred.

vim.buffers						*python-buffers*
	A mapping object providing access to the list of vim buffers.  The
	object supports the following operations: >
	    :py b = vim.buffers[i]	# Indexing (read-only)
	    :py b in vim.buffers	# Membership test
	    :py n = len(vim.buffers)	# Number of elements
	    :py for b in vim.buffers:	# Iterating over buffer list
<
vim.windows						*python-windows*
	A sequence object providing access to the list of vim windows.  The
	object supports the following operations: >
	    :py w = vim.windows[i]	# Indexing (read-only)
	    :py w in vim.windows	# Membership test
	    :py n = len(vim.windows)	# Number of elements
	    :py for w in vim.windows:	# Sequential access
<	Note: vim.windows object always accesses current tab page,. 
	|python-tabpage|.windows objects are bound to parent |python-tabpage| 
	object and always use windows from that tab page (or throw vim.error 
	in case tab page was deleted). You can keep a reference to both 
	without keeping a reference to vim module object or |python-tabpage|, 
	they will not lose their properties in this case.

vim.tabpages						*python-tabpages*
	A sequence object providing access to the list of vim tab pages. The 
	object supports the following operations: >
	    :py t = vim.tabpages[i]	# Indexing (read-only)
	    :py t in vim.tabpages	# Membership test
	    :py n = len(vim.tabpages)	# Number of elements
	    :py for t in vim.tabpages:	# Sequential access
<
vim.current						*python-current*
	An object providing access (via specific attributes) to various
	"current" objects available in vim:
		vim.current.line	The current line (RW)		String
		vim.current.buffer	The current buffer (RW)		Buffer
		vim.current.window	The current window (RW)		Window
		vim.current.tabpage	The current tab page (RW)	TabPage
		vim.current.range	The current line range (RO)	Range

	The last case deserves a little explanation.  When the :python or
	:pyfile command specifies a range, this range of lines becomes the
	"current range".  A range is a bit like a buffer, but with all access
	restricted to a subset of lines.  See |python-range| for more details.

	Note: When assigning to vim.current.{buffer,window,tabpage} it expects 
	valid |python-buffer|, |python-window| or |python-tabpage| objects 
	respectively. Assigning triggers normal (with |autocommand|s) 
	switching to given buffer, window or tab page. It is the only way to 
	switch UI objects in python: you can't assign to 
	|python-tabpage|.window attribute. To switch without triggering 
	autocommands use >
	    py << EOF
	    saved_eventignore = vim.options['eventignore']
	    vim.options['eventignore'] = 'all'
	    try:
	        vim.current.buffer = vim.buffers[2] # Switch to buffer 2
	    finally:
	        vim.options['eventignore'] = saved_eventignore
	    EOF
<
vim.vars						*python-vars*
vim.vvars						*python-vvars*
	Dictionary-like objects holding dictionaries with global (|g:|) and 
	vim (|v:|) variables respectively. Identical to `vim.bindeval("g:")`, 
	but faster.

vim.options						*python-options*
	Object partly supporting mapping protocol (supports setting and 
	getting items) providing a read-write access to global options.
	Note: unlike |:set| this provides access only to global options. You
	cannot use this object to obtain or set local options' values or
	access local-only options in any fashion. Raises KeyError if no global
	option with such name exists (i.e. does not raise KeyError for
	|global-local| options and global only options, but does for window-
	and buffer-local ones).  Use |python-buffer| objects to access to
	buffer-local options and |python-window| objects to access to
	window-local options.

	Type of this object is available via "Options" attribute of vim 
	module.

Output from Python					*python-output*
	Vim displays all Python code output in the Vim message area.  Normal
	output appears as information messages, and error output appears as
	error messages.

	In implementation terms, this means that all output to sys.stdout
	(including the output from print statements) appears as information
	messages, and all output to sys.stderr (including error tracebacks)
	appears as error messages.

							*python-input*
	Input (via sys.stdin, including input() and raw_input()) is not
	supported, and may cause the program to crash.  This should probably be
	fixed.

==============================================================================
3. Buffer objects					*python-buffer*

Buffer objects represent vim buffers.  You can obtain them in a number of ways:
	- via vim.current.buffer (|python-current|)
	- from indexing vim.buffers (|python-buffers|)
	- from the "buffer" attribute of a window (|python-window|)

Buffer objects have two read-only attributes - name - the full file name for
the buffer, and number - the buffer number.  They also have three methods
(append, mark, and range; see below).

You can also treat buffer objects as sequence objects.  In this context, they
act as if they were lists (yes, they are mutable) of strings, with each
element being a line of the buffer.  All of the usual sequence operations,
including indexing, index assignment, slicing and slice assignment, work as
you would expect.  Note that the result of indexing (slicing) a buffer is a
string (list of strings).  This has one unusual consequence - b[:] is different
from b.  In particular, "b[:] = None" deletes the whole of the buffer, whereas
"b = None" merely updates the variable b, with no effect on the buffer.

Buffer indexes start at zero, as is normal in Python.  This differs from vim
line numbers, which start from 1.  This is particularly relevant when dealing
with marks (see below) which use vim line numbers.

The buffer object attributes are:
	b.vars		Dictionary-like object used to access 
			|buffer-variable|s.
	b.options	Mapping object (supports item getting, setting and 
			deleting) that provides access to buffer-local options 
			and buffer-local values of |global-local| options. Use 
			|python-window|.options if option is window-local, 
			this object will raise KeyError. If option is 
			|global-local| and local value is missing getting it 
			will return None.
	b.name		String, RW. Contains buffer name (full path).
			Note: when assigning to b.name |BufFilePre| and 
			|BufFilePost| autocommands are launched.
	b.number	Buffer number. Can be used as |python-buffers| key.
			Read-only.

The buffer object methods are:
	b.append(str)	Append a line to the buffer
	b.append(str, nr)  Idem, below line "nr"
	b.append(list)	Append a list of lines to the buffer
			Note that the option of supplying a list of strings to
			the append method differs from the equivalent method
			for Python's built-in list objects.
	b.append(list, nr)  Idem, below line "nr"
	b.mark(name)	Return a tuple (row,col) representing the position
			of the named mark (can also get the []"<> marks)
	b.range(s,e)	Return a range object (see |python-range|) which
			represents the part of the given buffer between line
			numbers s and e |inclusive|.

Note that when adding a line it must not contain a line break character '\n'.
A trailing '\n' is allowed and ignored, so that you can do: >
	:py b.append(f.readlines())

Buffer object type is available using "Buffer" attribute of vim module.

Examples (assume b is the current buffer) >
	:py print b.name		# write the buffer file name
	:py b[0] = "hello!!!"		# replace the top line
	:py b[:] = None			# delete the whole buffer
	:py del b[:]			# delete the whole buffer
	:py b[0:0] = [ "a line" ]	# add a line at the top
	:py del b[2]			# delete a line (the third)
	:py b.append("bottom")		# add a line at the bottom
	:py n = len(b)			# number of lines
	:py (row,col) = b.mark('a')	# named mark
	:py r = b.range(1,5)		# a sub-range of the buffer
	:py b.vars["foo"] = "bar"	# assign b:foo variable
	:py b.options["ff"] = "dos"	# set fileformat
	:py del b.options["ar"]		# same as :set autoread<

==============================================================================
4. Range objects					*python-range*

Range objects represent a part of a vim buffer.  You can obtain them in a
number of ways:
	- via vim.current.range (|python-current|)
	- from a buffer's range() method (|python-buffer|)

A range object is almost identical in operation to a buffer object.  However,
all operations are restricted to the lines within the range (this line range
can, of course, change as a result of slice assignments, line deletions, or
the range.append() method).

The range object attributes are:
	r.start		Index of first line into the buffer
	r.end		Index of last line into the buffer

The range object methods are:
	r.append(str)	Append a line to the range
	r.append(str, nr)  Idem, after line "nr"
	r.append(list)	Append a list of lines to the range
			Note that the option of supplying a list of strings to
			the append method differs from the equivalent method
			for Python's built-in list objects.
	r.append(list, nr)  Idem, after line "nr"

Range object type is available using "Range" attribute of vim module.

Example (assume r is the current range):
	# Send all lines in a range to the default printer
	vim.command("%d,%dhardcopy!" % (r.start+1,r.end+1))

==============================================================================
5. Window objects					*python-window*

Window objects represent vim windows.  You can obtain them in a number of ways:
	- via vim.current.window (|python-current|)
	- from indexing vim.windows (|python-windows|)
	- from indexing "windows" attribute of a tab page (|python-tabpage|)
	- from the "window" attribute of a tab page (|python-tabpage|)

You can manipulate window objects only through their attributes.  They have no
methods, and no sequence or other interface.

Window attributes are:
	buffer (read-only)	The buffer displayed in this window
	cursor (read-write)	The current cursor position in the window
				This is a tuple, (row,col).
	height (read-write)	The window height, in rows
	width (read-write)	The window width, in columns
	vars (read-only)	The window |w:| variables. Attribute is 
				unassignable, but you can change window 
				variables this way
	options (read-only)	The window-local options. Attribute is 
				unassignable, but you can change window 
				options this way. Provides access only to 
				window-local options, for buffer-local use 
				|python-buffer| and for global ones use 
				|python-options|. If option is |global-local| 
				and local value is missing getting it will 
				return None.
	number (read-only)	Window number.  The first window has number 1.
				This is zero in case it cannot be determined
				(e.g. when the window object belongs to other
				tab page).
	row, col (read-only)	On-screen window position in display cells.
				First position is zero.
	tabpage (read-only)	Window tab page.

The height attribute is writable only if the screen is split horizontally.
The width attribute is writable only if the screen is split vertically.

Window object type is available using "Window" attribute of vim module.

==============================================================================
6. Tab page objects					*python-tabpage*

Tab page objects represent vim tab pages. You can obtain them in a number of 
ways:
	- via vim.current.tabpage (|python-current|)
	- from indexing vim.tabpages (|python-tabpages|)

You can use this object to access tab page windows. They have no methods and 
no sequence or other interfaces.

Tab page attributes are:
	number		The tab page number like the one returned by 
			|tabpagenr()|.
	windows		Like |python-windows|, but for current tab page.
	vars		The tab page |t:| variables.
	window		Current tabpage window.

TabPage object type is available using "TabPage" attribute of vim module.

==============================================================================
7. vim.bindeval objects				*python-bindeval-objects*

vim.Dictionary object				*python-Dictionary*
    Dictionary-like object providing access to vim |Dictionary| type.
    Attributes:
        Attribute  Description ~
        locked     One of                       *python-.locked*
                    Value           Description ~
                    zero            Variable is not locked
                    vim.VAR_LOCKED  Variable is locked, but can be unlocked
                    vim.VAR_FIXED   Variable is locked and can't be unlocked
                   Read-write. You can unlock locked variable by assigning 
                   `True` or `False` to this attribute. No recursive locking 
                   is supported.
        scope      One of
                    Value              Description ~
                    zero               Dictionary is not a scope one
                    vim.VAR_DEF_SCOPE  |g:| or |l:| dictionary
                    vim.VAR_SCOPE      Other scope dictionary,
                                       see |internal-variables|
    Methods (note: methods do not support keyword arguments):
        Method      Description ~
        keys()      Returns a list with dictionary keys.
        values()    Returns a list with dictionary values.
        items()     Returns a list of 2-tuples with dictionary contents.
        update(iterable), update(dictionary), update(**kwargs)
                    Adds keys to dictionary.
        get(key[, default=None])
                    Obtain key from dictionary, returning the default if it is 
                    not present.
        pop(key[, default])
                    Remove specified key from dictionary and return 
                    corresponding value. If key is not found and default is 
                    given returns the default, otherwise raises KeyError.
        popitem(key)
                    Remove specified key from dictionary and return a pair 
                    with it and the corresponding value. Returned key is a new 
                    object.
        has_key(key)
                    Check whether dictionary contains specified key, similar 
                    to `key in dict`.

        __new__(), __new__(iterable), __new__(dictionary), __new__(update)
                    You can use `vim.Dictionary()` to create new vim 
                    dictionaries. `d=vim.Dictionary(arg)` is the same as 
                    `d=vim.bindeval('{}');d.update(arg)`. Without arguments 
                    constructs empty dictionary.

    Examples: >
        d = vim.Dictionary(food="bar")		# Constructor
        d['a'] = 'b'				# Item assignment
        print d['a']				# getting item
        d.update({'c': 'd'})			# .update(dictionary)
        d.update(e='f')				# .update(**kwargs)
        d.update((('g', 'h'), ('i', 'j')))	# .update(iterable)
        for key in d.keys():			# .keys()
        for val in d.values():			# .values()
        for key, val in d.items():		# .items()
        print isinstance(d, vim.Dictionary)	# True
        for key in d:				# Iteration over keys
        class Dict(vim.Dictionary):		# Subclassing
<
    Note: when iterating over keys you should not modify dictionary.

vim.List object					*python-List*
    Sequence-like object providing access to vim |List| type.
    Supports `.locked` attribute, see |python-.locked|. Also supports the 
    following methods:
        Method          Description ~
        extend(item)    Add items to the list.

        __new__(), __new__(iterable)
                        You can use `vim.List()` to create new vim lists. 
                        `l=vim.List(iterable)` is the same as 
                        `l=vim.bindeval('[]');l.extend(iterable)`. Without 
                        arguments constructs empty list.
    Examples: >
        l = vim.List("abc")		# Constructor, result: ['a', 'b', 'c']
        l.extend(['abc', 'def'])	# .extend() method
        print l[1:]			# slicing
        l[:0] = ['ghi', 'jkl']		# slice assignment
        print l[0]			# getting item
        l[0] = 'mno'			# assignment
        for i in l:			# iteration
        print isinstance(l, vim.List)	# True
        class List(vim.List):		# Subclassing

vim.Function object				*python-Function*
    Function-like object, acting like vim |Funcref| object. Supports `.name` 
    attribute and is callable. Accepts special keyword argument `self`, see 
    |Dictionary-function|. You can also use `vim.Function(name)` constructor, 
    it is the same as `vim.bindeval('function(%s)'%json.dumps(name))`.

    Examples: >
        f = vim.Function('tr')			# Constructor
        print f('abc', 'a', 'b')		# Calls tr('abc', 'a', 'b')
        vim.command('''
            function DictFun() dict
                return self
            endfunction
        ''')
        f = vim.bindeval('function("DictFun")')
        print f(self={})			# Like call('DictFun', [], {})
        print isinstance(f, vim.Function)	# True

==============================================================================
8. pyeval() and py3eval() Vim functions			*python-pyeval*

To facilitate bi-directional interface, you can use |pyeval()| and |py3eval()| 
functions to evaluate Python expressions and pass their values to VimL.

==============================================================================
9. Dynamic loading					*python-dynamic*

On MS-Windows the Python library can be loaded dynamically.  The |:version|
output then includes |+python/dyn|.

This means that Vim will search for the Python DLL file only when needed.
When you don't use the Python interface you don't need it, thus you can use
Vim without this DLL file.

To use the Python interface the Python DLL must be in your search path.  In a
console window type "path" to see what directories are used.

The name of the DLL must match the Python version Vim was compiled with.
Currently the name is "python24.dll".  That is for Python 2.4.  To know for
sure edit "gvim.exe" and search for "python\d*.dll\c".

==============================================================================
10. Python 3						*python3*

							*:py3* *:python3*
The `:py3` and `:python3` commands work similar to `:python`.  A simple check
if the `:py3` command is working: >
	:py3 print("Hello")
<							*:py3file*
The `:py3file` command works similar to `:pyfile`.
							*:py3do* *E863*
The `:py3do` command works similar to `:pydo`.


Vim can be built in four ways (:version output):
1. No Python support	    (-python, -python3)
2. Python 2 support only    (+python or +python/dyn, -python3)
3. Python 3 support only    (-python, +python3 or +python3/dyn)
4. Python 2 and 3 support   (+python/dyn, +python3/dyn)

Some more details on the special case 4:

When Python 2 and Python 3 are both supported they must be loaded dynamically.

When doing this on Linux/Unix systems and importing global symbols, this leads
to a crash when the second Python version is used.  So either global symbols
are loaded but only one Python version is activated, or no global symbols are
loaded. The latter makes Python's "import" fail on libraries that expect the
symbols to be provided by Vim.
							*E836* *E837*
Vim's configuration script makes a guess for all libraries based on one
standard Python library (termios).  If importing this library succeeds for
both Python versions, then both will be made available in Vim at the same
time.  If not, only the version first used in a session will be enabled.
When trying to use the other one you will get the E836 or E837 error message.

Here Vim's behavior depends on the system in which it was configured.  In a
system where both versions of Python were configured with --enable-shared,
both versions of Python will be activated at the same time.  There will still
be problems with other third party libraries that were not linked to
libPython.

To work around such problems there are these options:
1. The problematic library is recompiled to link to the according
   libpython.so.
2. Vim is recompiled for only one Python version.
3. You undefine PY_NO_RTLD_GLOBAL in auto/config.h after configuration.  This
   may crash Vim though.

							*has-python*
You can test what Python version is available with: >
	if has('python')
	  echo 'there is Python 2.x'
  	elseif has('python3')
	  echo 'there is Python 3.x'
	endif

Note however, that when Python 2 and 3 are both available and loaded
dynamically, these has() calls will try to load them.  If only one can be
loaded at a time, just checking if Python 2 or 3 are available will prevent
the other one from being available.

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