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*if_pyth.txt*   For Vim version 7.3.  Last change: 2010 Aug 13


                  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. Dynamic loading              |python-dynamic|
7. 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}.

:[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.  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
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'}]



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 sequence 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:   # Sequential access
<
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
<
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.

                                                        *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 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(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())

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

==============================================================================
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"

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|)

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.

==============================================================================
6. 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".

==============================================================================
7. Python 3                                             *python3*

                                                        *:py3* *:python3*
The |:py3| and |:python3| commands work similar to |:python|.
                                                        *:py3file*
The |:py3file| command works similar to |:pyfile|.

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 libaries 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.


==============================================================================
 vim:tw=78:ts=8:ft=help:norl: