If_pyth

Nvim :help pages, generated from source using the tree-sitter-vimdoc parser.


The Python Interface to NVim python Python
See provider-python for more information.

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}. Useful for including python code in Vim scripts. Requires Python, see script-here.
The {endmarker} below the {script} 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.
Example:
function! IcecreamInitialize()
python << EOF
class StrawberryIcecream:
        def __call__(self):
                print 'EAT ME'
EOF
endfunction
To see what version of Python you have:
:python print(sys.version)
There is no need to "import sys", it's done by default.
python-environment Environment variables set in Vim are not always available in Python. This depends on how Vim and Python were build. Also see https://docs.python.org/3/library/os.html#os.environ
Note: Python is very sensitive to 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,$".
Examples:
:pydo return "%s\t%d" % (line[::-1], len(line))
:pydo if line: return "%4d: %s" % (linenr, line)
One can use :pydo in possible conjunction with :py to filter a range using python. For example:
:py3 << EOF
needle = vim.eval('@a')
replacement = vim.eval('@b')

def py_vim_string_replace(str):
        return str.replace(needle, replacement)
EOF
:'<,'>py3do return py_vim_string_replace(line)
:pyfile :pyf :[range]pyf[ile] {file} Execute the Python script in {file}. The whole argument is used as a single file name.
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 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 (such as the "import" statements) persist from one command to the next, just like the Python REPL.
script-here When using a script language in-line, you might want to skip this when the language isn't supported. Note that this mechanism doesn't work:
if has('python')
  python << EOF
    this will NOT work!
EOF
endif
Instead, put the Python command in a function and call that function:
if has('python')
  function DefPython()
    python << EOF
      this works
EOF
  endfunction
  call DefPython()
endif
Note that "EOF" must be at the start of the line.

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.
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.
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.
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}/python3 and {rtp}/pythonx 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}/python3 and {rtp}/pythonx directories for each {rtp} in 'runtimepath'.

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<

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))

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.

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.

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 Vim script. pyxeval() is also available.

Python 3 python3

As Python 3 is the only supported version in Nvim, "python" is synonymous with "python3" in the current version. However, code that aims to support older versions of Neovim, as well as Vim, should prefer to use "python3" variants explicitly if Python 3 is required.
:py3 :python3 :[range]py3 {stmt} :[range]py3 << [endmarker] {script} {endmarker}
:[range]python3 {stmt} :[range]python3 << [endmarker] {script} {endmarker} 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 :[range]py3f[ile] {file} The :py3file command works similar to :pyfile. :py3do :[range]py3do {body} The :py3do command works similar to :pydo.
E880 Raising SystemExit exception in python isn't endorsed way to quit vim, use:
:py vim.command("qall!")
has-python You can test if Python is available with:
if has('pythonx')
  echo 'there is Python'
endif
  if has('python3')
  echo 'there is Python 3.x'
endif
Python 2 is no longer supported. Thus has('python') always returns zero for backwards compatibility reasons.

Python X python_x pythonx

The "pythonx" and "pyx" prefixes were introduced for python code which works with Python 2.6+ and Python 3. As Nvim only supports Python 3, all these commands are now synonymous to their "python3" equivalents.
:pyx :pythonx :pyx and :pythonx work the same as :python3. To check if :pyx works:
:pyx print("Hello")
To see what version of Python is being used:
:pyx import sys
:pyx print(sys.version)
:pyxfile python_x-special-comments :pyxfile works the same as :py3file.
:pyxdo :pyxdo works the same as :py3do.
has-pythonx To check if pyx* functions and commands are available:
if has('pythonx')
  echo 'pyx* commands are available. (Python ' .. &pyx .. ')'
endif
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