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Issue #6953: Rearrange and expand Readline module documentation 

* Group functions into six new subsections
* Document the underlying Readline function or variable accessed
* get_history_length() returns the history file limit
* clear_history() is conditionally compiled in
* Clarify zero and one bases for history item indexes
* parse_and_bind() uses its argument directly as an init line
* Change "command line" to "line buffer" for consistency
* read_init_file() also executes the file
* read_history_file() replaces the previous history
* write_history_file() overwrites any existing file
* Differentiate history file lines from history list items, which could be
  multi-line
* Add more information about completion, also addressing Issue #10796
* libedit (Editline) may be used on any platform; detection is OS X specific
This commit is contained in:
Martin Panter 2016-04-05 07:37:22 +00:00
parent cc71a795df
commit 0f7673943a
3 changed files with 148 additions and 87 deletions
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199
Doc/library/readline.rst
View File

@ -9,15 +9,18 @@
The :mod:`readline` module defines a number of functions to facilitate
completion and reading/writing of history files from the Python interpreter.
This module can be used directly or via the :mod:`rlcompleter` module. Settings
This module can be used directly, or via the :mod:`rlcompleter` module, which
supports completion of Python identifiers at the interactive prompt. Settings
made using this module affect the behaviour of both the interpreter's
interactive prompt and the prompts offered by the built-in :func:`input`
function.
.. note::
On MacOS X the :mod:`readline` module can be implemented using
The underlying Readline library API may be implemented by
the ``libedit`` library instead of GNU readline.
On MacOS X the :mod:`readline` module detects which library is being used
at run time.
The configuration file for ``libedit`` is different from that
of GNU readline. If you programmatically load configuration strings
@ -25,112 +28,168 @@ function.
to differentiate between GNU readline and libedit.
The :mod:`readline` module defines the following functions:
Init file
---------
The following functions relate to the init file and user configuration:
.. function:: parse_and_bind(string)
Parse and execute single line of a readline init file.
.. function:: get_line_buffer()
Return the current contents of the line buffer.
.. function:: insert_text(string)
Insert text into the command line.
Execute the init line provided in the *string* argument. This calls
:c:func:`rl_parse_and_bind` in the underlying library.
.. function:: read_init_file([filename])
Parse a readline initialization file. The default filename is the last filename
used.
Execute a readline initialization file. The default filename is the last filename
used. This calls :c:func:`rl_read_init_file` in the underlying library.
Line buffer
-----------
The following functions operate on the line buffer:
.. function:: get_line_buffer()
Return the current contents of the line buffer (:c:data:`rl_line_buffer`
in the underlying library).
.. function:: insert_text(string)
Insert text into the line buffer at the cursor position. This calls
:c:func:`rl_insert_text` in the underlying library, but ignores
the return value.
.. function:: redisplay()
Change what's displayed on the screen to reflect the current contents of the
line buffer. This calls :c:func:`rl_redisplay` in the underlying library.
History file
------------
The following functions operate on a history file:
.. function:: read_history_file([filename])
Load a readline history file. The default filename is :file:`~/.history`.
Load a readline history file, and append it to the history list.
The default filename is :file:`~/.history`. This calls
:c:func:`read_history` in the underlying library.
.. function:: write_history_file([filename])
Save a readline history file. The default filename is :file:`~/.history`.
Save the history list to a readline history file, overwriting any
existing file. The default filename is :file:`~/.history`. This calls
:c:func:`write_history` in the underlying library.
.. function:: append_history_file(nelements[, filename])
Append the last *nelements* of history to a file. The default filename is
:file:`~/.history`. The file must already exist.
Append the last *nelements* items of history to a file. The default filename is
:file:`~/.history`. The file must already exist. This calls
:c:func:`append_history` in the underlying library.
.. versionadded:: 3.5
.. function:: get_history_length()
set_history_length(length)
Set or return the desired number of lines to save in the history file.
The :func:`write_history_file` function uses this value to truncate
the history file, by calling :c:func:`history_truncate_file` in
the underlying library. Negative values imply
unlimited history file size.
History list
------------
The following functions operate on a global history list:
.. function:: clear_history()
Clear the current history. (Note: this function is not available if the
installed version of GNU readline doesn't support it.)
.. function:: get_history_length()
Return the desired length of the history file. Negative values imply unlimited
history file size.
.. function:: set_history_length(length)
Set the number of lines to save in the history file. :func:`write_history_file`
uses this value to truncate the history file when saving. Negative values imply
unlimited history file size.
Clear the current history. This calls :c:func:`clear_history` in the
underlying library. The Python function only exists if Python was
compiled for a version of the library that supports it.
.. function:: get_current_history_length()
Return the number of lines currently in the history. (This is different from
Return the number of items currently in the history. (This is different from
:func:`get_history_length`, which returns the maximum number of lines that will
be written to a history file.)
.. function:: get_history_item(index)
Return the current contents of history item at *index*.
Return the current contents of history item at *index*. The item index
is one-based. This calls :c:func:`history_get` in the underlying library.
.. function:: remove_history_item(pos)
Remove history item specified by its position from the history.
The position is zero-based. This calls :c:func:`remove_history` in
the underlying library.
.. function:: replace_history_item(pos, line)
Replace history item specified by its position with the given line.
Replace history item specified by its position with *line*.
The position is zero-based. This calls :c:func:`replace_history_entry`
in the underlying library.
.. function:: redisplay()
.. function:: add_history(line)
Change what's displayed on the screen to reflect the current contents of the
line buffer.
Append *line* to the history buffer, as if it was the last line typed.
This calls :c:func:`add_history` in the underlying library.
Startup hooks
-------------
.. function:: set_startup_hook([function])
Set or remove the startup_hook function. If *function* is specified, it will be
used as the new startup_hook function; if omitted or ``None``, any hook function
already installed is removed. The startup_hook function is called with no
Set or remove the function invoked by the :c:data:`rl_startup_hook`
callback of the underlying library. If *function* is specified, it will
be used as the new hook function; if omitted or ``None``, any function
already installed is removed. The hook is called with no
arguments just before readline prints the first prompt.
.. function:: set_pre_input_hook([function])
Set or remove the pre_input_hook function. If *function* is specified, it will
be used as the new pre_input_hook function; if omitted or ``None``, any hook
function already installed is removed. The pre_input_hook function is called
Set or remove the function invoked by the :c:data:`rl_pre_input_hook`
callback of the underlying library. If *function* is specified, it will
be used as the new hook function; if omitted or ``None``, any
function already installed is removed. The hook is called
with no arguments after the first prompt has been printed and just before
readline starts reading input characters.
Completion
----------
The following functions relate to implementing a custom word completion
function. This is typically operated by the Tab key, and can suggest and
automatically complete a word being typed. By default, Readline is set up
to be used by :mod:`rlcompleter` to complete Python identifiers for
the interactive interpreter. If the :mod:`readline` module is to be used
with a custom completer, a different set of word delimiters should be set.
.. function:: set_completer([function])
Set or remove the completer function. If *function* is specified, it will be
@ -140,6 +199,12 @@ The :mod:`readline` module defines the following functions:
returns a non-string value. It should return the next possible completion
starting with *text*.
The installed completer function is invoked by the *entry_func* callback
passed to :c:func:`rl_completion_matches` in the underlying library.
The *text* string comes from the first parameter to the
:c:data:`rl_attempted_completion_function` callback of the
underlying library.
.. function:: get_completer()
@ -148,27 +213,27 @@ The :mod:`readline` module defines the following functions:
.. function:: get_completion_type()
Get the type of completion being attempted.
Get the type of completion being attempted. This returns the
:c:data:`rl_completion_type` variable in the underlying library as
an integer.
.. function:: get_begidx()
get_endidx()
Get the beginning index of the readline tab-completion scope.
.. function:: get_endidx()
Get the ending index of the readline tab-completion scope.
Get the beginning or ending index of the completion scope.
These indexes are the *start* and *end* arguments passed to the
:c:data:`rl_attempted_completion_function` callback of the
underlying library.
.. function:: set_completer_delims(string)
get_completer_delims()
Set the readline word delimiters for tab-completion.
.. function:: get_completer_delims()
Get the readline word delimiters for tab-completion.
Set or get the word delimiters for completion. These determine the
start of the word to be considered for completion (the completion scope).
These functions access the :c:data:`rl_completer_word_break_characters`
variable in the underlying library.
.. function:: set_completion_display_matches_hook([function])
@ -176,21 +241,13 @@ The :mod:`readline` module defines the following functions:
Set or remove the completion display function. If *function* is
specified, it will be used as the new completion display function;
if omitted or ``None``, any completion display function already
installed is removed. The completion display function is called as
installed is removed. This sets or clears the
:c:data:`rl_completion_display_matches_hook` callback in the
underlying library. The completion display function is called as
``function(substitution, [matches], longest_match_length)`` once
each time matches need to be displayed.
.. function:: add_history(line)
Append a line to the history buffer, as if it was the last line typed.
.. seealso::
Module :mod:`rlcompleter`
Completion of Python identifiers at the interactive prompt.
.. _readline-example:
Example

4
Misc/NEWS
View File

@ -340,6 +340,10 @@ Library
Documentation
-------------
- Issue #6953: Rework the Readline module documentation to group related
functions together, and add more details such as what underlying Readline
functions and variables are accessed.
- Issue #23606: Adds note to ctypes documentation regarding cdll.msvcrt.
- Issue #25500: Fix documentation to not claim that __import__ is searched for

32
Modules/readline.c
View File

@ -149,7 +149,7 @@ parse_and_bind(PyObject *self, PyObject *args)
PyDoc_STRVAR(doc_parse_and_bind,
"parse_and_bind(string) -> None\n\
Parse and execute single line of a readline init file.");
Execute the init line provided in the string argument.");
/* Exported function to parse a readline init file */
@ -174,7 +174,7 @@ read_init_file(PyObject *self, PyObject *args)
PyDoc_STRVAR(doc_read_init_file,
"read_init_file([filename]) -> None\n\
Parse a readline initialization file.\n\
Execute a readline initialization file.\n\
The default filename is the last filename used.");
@ -271,7 +271,7 @@ append_history_file(PyObject *self, PyObject *args)
PyDoc_STRVAR(doc_append_history_file,
"append_history_file(nelements[, filename]) -> None\n\
Append the last nelements of the history list to file.\n\
Append the last nelements items of the history list to file.\n\
The default filename is ~/.history.");
#endif
@ -290,7 +290,7 @@ set_history_length(PyObject *self, PyObject *args)
PyDoc_STRVAR(set_history_length_doc,
"set_history_length(length) -> None\n\
set the maximal number of items which will be written to\n\
set the maximal number of lines which will be written to\n\
the history file. A negative length is used to inhibit\n\
history truncation.");
@ -305,7 +305,7 @@ get_history_length(PyObject *self, PyObject *noarg)
PyDoc_STRVAR(get_history_length_doc,
"get_history_length() -> int\n\
return the maximum number of items that will be written to\n\
return the maximum number of lines that will be written to\n\
the history file.");
@ -373,7 +373,7 @@ set_startup_hook(PyObject *self, PyObject *args)
PyDoc_STRVAR(doc_set_startup_hook,
"set_startup_hook([function]) -> None\n\
Set or remove the startup_hook function.\n\
Set or remove the function invoked by the rl_startup_hook callback.\n\
The function is called with no arguments just\n\
before readline prints the first prompt.");
@ -390,7 +390,7 @@ set_pre_input_hook(PyObject *self, PyObject *args)
PyDoc_STRVAR(doc_set_pre_input_hook,
"set_pre_input_hook([function]) -> None\n\
Set or remove the pre_input_hook function.\n\
Set or remove the function invoked by the rl_pre_input_hook callback.\n\
The function is called with no arguments after the first prompt\n\
has been printed and just before readline starts reading input\n\
characters.");
@ -421,7 +421,7 @@ get_begidx(PyObject *self, PyObject *noarg)
PyDoc_STRVAR(doc_get_begidx,
"get_begidx() -> int\n\
get the beginning index of the readline tab-completion scope");
get the beginning index of the completion scope");
/* Get the ending index for the scope of the tab-completion */
@ -435,7 +435,7 @@ get_endidx(PyObject *self, PyObject *noarg)
PyDoc_STRVAR(doc_get_endidx,
"get_endidx() -> int\n\
get the ending index of the readline tab-completion scope");
get the ending index of the completion scope");
/* Set the tab-completion word-delimiters that readline uses */
@ -464,7 +464,7 @@ set_completer_delims(PyObject *self, PyObject *args)
PyDoc_STRVAR(doc_set_completer_delims,
"set_completer_delims(string) -> None\n\
set the readline word delimiters for tab-completion");
set the word delimiters for completion");
/* _py_free_history_entry: Utility function to free a history entry. */
@ -504,7 +504,7 @@ py_remove_history(PyObject *self, PyObject *args)
int entry_number;
HIST_ENTRY *entry;
if (!PyArg_ParseTuple(args, "i:remove_history", &entry_number))
if (!PyArg_ParseTuple(args, "i:remove_history_item", &entry_number))
return NULL;
if (entry_number < 0) {
PyErr_SetString(PyExc_ValueError,
@ -534,7 +534,7 @@ py_replace_history(PyObject *self, PyObject *args)
char *line;
HIST_ENTRY *old_entry;
if (!PyArg_ParseTuple(args, "is:replace_history", &entry_number,
if (!PyArg_ParseTuple(args, "is:replace_history_item", &entry_number,
&line)) {
return NULL;
}
@ -575,7 +575,7 @@ py_add_history(PyObject *self, PyObject *args)
PyDoc_STRVAR(doc_add_history,
"add_history(string) -> None\n\
add a line to the history buffer");
add an item to the history buffer");
/* Get the tab-completion word-delimiters that readline uses */
@ -588,7 +588,7 @@ get_completer_delims(PyObject *self, PyObject *noarg)
PyDoc_STRVAR(doc_get_completer_delims,
"get_completer_delims() -> string\n\
get the readline word delimiters for tab-completion");
get the word delimiters for completion");
/* Set the completer function */
@ -649,7 +649,7 @@ get_history_item(PyObject *self, PyObject *args)
int idx = 0;
HIST_ENTRY *hist_ent;
if (!PyArg_ParseTuple(args, "i:index", &idx))
if (!PyArg_ParseTuple(args, "i:get_history_item", &idx))
return NULL;
#ifdef __APPLE__
if (using_libedit_emulation) {
@ -741,7 +741,7 @@ insert_text(PyObject *self, PyObject *args)
PyDoc_STRVAR(doc_insert_text,
"insert_text(string) -> None\n\
Insert text into the command line.");
Insert text into the line buffer at the cursor position.");
/* Redisplay the line buffer */