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if_pyth.txt   For Vim version 8.0.  Last change: 2016 Sep 17


                  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.
Both can be available at the same time, but read python-2-and-3.

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

                                        :python :py E263 E264 E887
:[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

To see what version of Python you have: 
        :python import sys
        :python print(sys.version)

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 objects.

vim.strwidth(str)                                       python-strwidth
        Like strwidth(): returns number of display cells str occupies, tab 
        is counted as one cell.

vim.foreach_rtp(callable)                               python-foreach_rtp
        Call the given callable for each path in 'runtimepath' until either 
        callable returns something but None, the exception is raised or there 
        are no longer paths. If stopped in case callable returned non-None, 
        vim.foreach_rtp function returns the value returned by callable.

vim.chdir(*args, **kwargs)                              python-chdir
vim.fchdir(*args, **kwargs)                             python-fchdir
        Run os.chdir or os.fchdir, then all appropriate vim stuff.
        Note: you should not use these functions directly, use os.chdir and 
              os.fchdir instead. Behavior of vim.fchdir is undefined in case 
              os.fchdir does not exist.

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 autocommands) 
        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.

                    python2-directory python3-directory pythonx-directory
Python 'runtimepath' handling                           python-special-path

In python vim.VIM_SPECIAL_PATH special directory is used as a replacement for 
the list of paths found in 'runtimepath': with this directory in sys.path and 
vim.path_hooks in sys.path_hooks python will try to load module from 
{rtp}/python2 (or python3) and {rtp}/pythonx (for both python versions) for 
each {rtp} found in 'runtimepath'.

Implementation is similar to the following, but written in C: 

    from imp import find_module, load_module
    import vim
    import sys

    class VimModuleLoader(object):
        def __init__(self, module):
            self.module = module

        def load_module(self, fullname, path=None):
            return self.module

    def _find_module(fullname, oldtail, path):
        idx = oldtail.find('.')
        if idx > 0:
            name = oldtail[:idx]
            tail = oldtail[idx+1:]
            fmr = find_module(name, path)
            module = load_module(fullname[:-len(oldtail)] + name, *fmr)
            return _find_module(fullname, tail, module.__path__)
        else:
            fmr = find_module(fullname, path)
            return load_module(fullname, *fmr)

    # It uses vim module itself in place of VimPathFinder class: it does not 
    # matter for python which object has find_module function attached to as 
    # an attribute.
    class VimPathFinder(object):
        @classmethod
        def find_module(cls, fullname, path=None):
            try:
                return VimModuleLoader(_find_module(fullname, fullname, path or vim._get_paths()))
            except ImportError:
                return None

        @classmethod
        def load_module(cls, fullname, path=None):
            return _find_module(fullname, fullname, path or vim._get_paths())

    def hook(path):
        if path == vim.VIM_SPECIAL_PATH:
            return VimPathFinder
        else:
            raise ImportError

    sys.path_hooks.append(hook)

vim.VIM_SPECIAL_PATH                                    python-VIM_SPECIAL_PATH
        String constant used in conjunction with vim path hook. If path hook 
        installed by vim is requested to handle anything but path equal to 
        vim.VIM_SPECIAL_PATH constant it raises ImportError. In the only other 
        case it uses special loader.

        Note: you must not use value of this constant directly, always use 
              vim.VIM_SPECIAL_PATH object.

vim.find_module(...)                                    python-find_module
vim.path_hook(path)                                     python-path_hook
        Methods or objects used to implement path loading as described above. 
        You should not be using any of these directly except for vim.path_hook 
        in case you need to do something with sys.meta_path. It is not 
        guaranteed that any of the objects will exist in the future vim 
        versions.

vim._get_paths                                          python-_get_paths
        Methods returning a list of paths which will be searched for by path 
        hook. You should not rely on this method being present in future 
        versions, but can use it for debugging.

        It returns a list of {rtp}/python2 (or {rtp}/python3) and 
        {rtp}/pythonx directories for each {rtp} in 'runtimepath'.

==============================================================================
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-variables.
        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.
        b.valid         True or False. Buffer object becomes invalid when 
                        corresponding buffer is wiped out.

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.
        valid (read-write)      True or False. Window object becomes invalid 
                                when corresponding window is closed.

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.
        valid           True or False. Tab page object becomes invalid when 
                        corresponding tab page is closed.

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()
                    Remove random key from dictionary and return (key, value) 
                    pair.
        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. 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)).

    Attributes (read-only):
        Attribute    Description 
        name         Function name.
        args         None or a python-List object with arguments.  Note 
                     that this is a copy of the arguments list, constructed 
                     each time you request this attribute. Modifications made 
                     to the list will be ignored (but not to the containers 
                     inside argument list: this is like copy() and not 
                     deepcopy()).
        self         None or a python-Dictionary object with self 
                     dictionary. Note that explicit self keyword used when 
                     calling resulting object overrides this attribute.
        auto_rebind  Boolean. True if partial created from this Python object 
                     and stored in the VimL dictionary should be automatically 
                     rebound to the dictionary it is stored in when this 
                     dictionary is indexed. Exposes Vim internal difference 
                     between dict.func (auto_rebind=True) and 
                     function(dict.func,dict) (auto_rebind=False). This 
                     attribute makes no sense if self attribute is None.

    Constructor additionally accepts args, self and auto_rebind 
    keywords.  If args and/or self argument is given then it constructs 
    a partial, see function().  auto_rebind is only used when self 
    argument is given, otherwise it is assumed to be True regardless of 
    whether it was given or not.  If self is given then it defaults to 
    False.

    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

        p = vim.Function('DictFun', self={})
        print f()
        p = vim.Function('tr', args=['abc', 'a'])
        print f('b')

==============================================================================
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 and Unix the Python library can be loaded dynamically.  The
:version output then includes +python/dyn or +python3/dyn.

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


MS-Windows 

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 'pythondll'
or 'pythonthreedll' option can be also used to specify the Python DLL.

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".


Unix 

The 'pythondll' or 'pythonthreedll' option can be used to specify the Python
shared library file instead of DYNAMIC_PYTHON_DLL or DYNAMIC_PYTHON3_DLL file
what were specified at compile time.  The version of the shared library must
match the Python 2.x or Python 3 version Vim was compiled with.

==============================================================================
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")

To see what version of Python you have: 
        :py3 import sys
        :py3 print(sys.version)
                                                       :py3file
The :py3file command works similar to :pyfile.
                                                        :py3do
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:  python-2-and-3

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.

                                                        E880
Raising SystemExit exception in python isn't endorsed way to quit vim, use: 
        :py vim.command("qall!")


                                                        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.

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

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