Vim documentation: if_pyth

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*if_pyth.txt*   For Vim version 6.3.  Last change: 2004 Feb 28

		  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|

{Vi does not have any of these commands}

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


1. Commands						*python-commands*

					*:python* *:py* *E205* *E263* *E264*
:[range]py[thon] {stmt}
			Execute Python statement {stmt}.

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

{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.

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

							*: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

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"]

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

	print "Hello"			# displays a message
	vim.command(cmd)		# execute an ex command
	w =[n]		# gets window "n"
	cw = vim.current.window		# gets the current window
	b = vim.buffers[n]		# gets buffer "n"
	cb = vim.current.buffer		# gets the current buffer
	w.height = lines		# sets the window height
	w.cursor = (row, col)		# sets the window cursor position
	pos = w.cursor			# gets a tuple (row, col)
	name =			# gets the buffer file name
	line = b[n]			# gets a line from the buffer
	lines = b[n:m]			# gets a list of lines
	num = len(b)			# gets the number of lines
	b[n] = str			# sets a line in the buffer
	b[n:m] = [str1, str2, str3]	# sets a number of lines at once
	del b[n]			# deletes a line
	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.
		vim.command("set tw=72")
 	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

	The ":python" command cannot be used recursively with Python 2.2 and
	older.  This only works with Python 2.3 and later:
		:python 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
		text_width = vim.eval("&tw")
		str = vim.eval("12+12")		# NB result is a string! Use
						# string.atoi() to convert to
						# a number.

Error object of the "vim" module

vim.error						*python-error*
	Upon encountering a Vim error, Python raises an exception of type
			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 sequence object providing access to the list of vim buffers. The
	object supports the following operations:
		b = vim.buffers[i]	# Indexing (read-only)
		b in vim.buffers	# Membership test
		n = len(vim.buffers)	# Number of elements
		for b in vim.buffers:	# Sequential access						*python-windows*
	A sequence object providing access to the list of vim windows. The
	object supports the following operations:
		w =[i]	# Indexing (read-only)
		w in	# Membership test
		n = len(	# Number of elements
		for w in	# 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 (RO)		Buffer
		vim.current.window	The current window (RO)		Window
		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.

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.

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


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 one read-only attribute - name - the full file name for
the buffer. 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 methods are:
	b.append(str)	Append a line to the buffer
	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.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|.

Examples (assume b is the current buffer)
	print		# write the buffer file name
	b[0] = "hello!!!"	# replace the top line
	b[:] = None		# delete the whole buffer
	del b[:]		# delete the whole buffer (same as above)
	b[0:0] = [ "a line" ]	# add a line at the top
	del b[2]		# delete a line (the third)
	b.append("bottom")	# add a line at the bottom
	n = len(b)		# number of lines
	(row,col) = b.mark('a') # named mark
	r = b.range(1,5)	# a sub-range of the buffer


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(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.

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 (|python-windows|)

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

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