Mercurial > vim
view runtime/doc/usr_26.txt @ 32936:c517845bd10e v9.0.1776
patch 9.0.1776: No support for stable Python 3 ABI
Commit: https://github.com/vim/vim/commit/c13b3d1350b60b94fe87f0761ea31c0e7fb6ebf3
Author: Yee Cheng Chin <ychin.git@gmail.com>
Date: Sun Aug 20 21:18:38 2023 +0200
patch 9.0.1776: No support for stable Python 3 ABI
Problem: No support for stable Python 3 ABI
Solution: Support Python 3 stable ABI
Commits:
1) Support Python 3 stable ABI to allow mixed version interoperatbility
Vim currently supports embedding Python for use with plugins, and the
"dynamic" linking option allows the user to specify a locally installed
version of Python by setting `pythonthreedll`. However, one caveat is
that the Python 3 libs are not binary compatible across minor versions,
and mixing versions can potentially be dangerous (e.g. let's say Vim was
linked against the Python 3.10 SDK, but the user sets `pythonthreedll`
to a 3.11 lib). Usually, nothing bad happens, but in theory this could
lead to crashes, memory corruption, and other unpredictable behaviors.
It's also difficult for the user to tell something is wrong because Vim
has no way of reporting what Python 3 version Vim was linked with.
For Vim installed via a package manager, this usually isn't an issue
because all the dependencies would already be figured out. For prebuilt
Vim binaries like MacVim (my motivation for working on this), AppImage,
and Win32 installer this could potentially be an issue as usually a
single binary is distributed. This is more tricky when a new Python
version is released, as there's a chicken-and-egg issue with deciding
what Python version to build against and hard to keep in sync when a new
Python version just drops and we have a mix of users of different Python
versions, and a user just blindly upgrading to a new Python could lead to
bad interactions with Vim.
Python 3 does have a solution for this problem: stable ABI / limited API
(see https://docs.python.org/3/c-api/stable.html). The C SDK limits the
API to a set of functions that are promised to be stable across
versions. This pull request adds an ifdef config that allows us to turn
it on when building Vim. Vim binaries built with this option should be
safe to freely link with any Python 3 libraies without having the
constraint of having to use the same minor version.
Note: Python 2 has no such concept and this doesn't change how Python 2
integration works (not that there is going to be a new version of Python
2 that would cause compatibility issues in the future anyway).
---
Technical details:
======
The stable ABI can be accessed when we compile with the Python 3 limited
API (by defining `Py_LIMITED_API`). The Python 3 code (in `if_python3.c`
and `if_py_both.h`) would now handle this and switch to limited API
mode. Without it set, Vim will still use the full API as before so this
is an opt-in change.
The main difference is that `PyType_Object` is now an opaque struct that
we can't directly create "static types" out of, and we have to create
type objects as "heap types" instead. This is because the struct is not
stable and changes from version to version (e.g. 3.8 added a
`tp_vectorcall` field to it). I had to change all the types to be
allocated on the heap instead with just a pointer to them.
Other functions are also simply missing in limited API, or they are
introduced too late (e.g. `PyUnicode_AsUTF8AndSize` in 3.10) to it that
we need some other ways to do the same thing, so I had to abstract a few
things into macros, and sometimes re-implement functions like
`PyObject_NEW`.
One caveat is that in limited API, `OutputType` (used for replacing
`sys.stdout`) no longer inherits from `PyStdPrinter_Type` which I don't
think has any real issue other than minor differences in how they
convert to a string and missing a couple functions like `mode()` and
`fileno()`.
Also fixed an existing bug where `tp_basicsize` was set incorrectly for
`BufferObject`, `TabListObject, `WinListObject`.
Technically, there could be a small performance drop, there is a little
more indirection with accessing type objects, and some APIs like
`PyUnicode_AsUTF8AndSize` are missing, but in practice I didn't see any
difference, and any well-written Python plugin should try to avoid
excessing callbacks to the `vim` module in Python anyway.
I only tested limited API mode down to Python 3.7, which seemes to
compile and work fine. I haven't tried earlier Python versions.
2) Fix PyIter_Check on older Python vers / type##Ptr unused warning
For PyIter_Check, older versions exposed them as either macros (used in
full API), or a function (for use in limited API). A previous change
exposed PyIter_Check to the dynamic build because Python just moved it
to function-only in 3.10 anyway. Because of that, just make sure we
always grab the function in dynamic builds in earlier versions since
that's what Python eventually did anyway.
3) Move Py_LIMITED_API define to configure script
Can now use --with-python-stable-abi flag to customize what stable ABI
version to target. Can also use an env var to do so as well.
4) Show +python/dyn-stable in :version, and allow has() feature query
Not sure if the "/dyn-stable" suffix would break things, or whether we
should do it another way. Or just don't show it in version and rely on
has() feature checking.
5) Documentation first draft. Still need to implement v:python3_version
6) Fix PyIter_Check build breaks when compiling against Python 3.8
7) Add CI coverage stable ABI on Linux/Windows / make configurable on Windows
This adds configurable options for Windows make files (both MinGW and
MSVC). CI will also now exercise both traditional full API and stable
ABI for Linux and Windows in the matrix for coverage.
Also added a "dynamic" option to Linux matrix as a drive-by change to
make other scripting languages like Ruby / Perl testable under both
static and dynamic builds.
8) Fix inaccuracy in Windows docs
Python's own docs are confusing but you don't actually want to use
`python3.dll` for the dynamic linkage.
9) Add generated autoconf file
10) Add v:python3_version support
This variable indicates the version of Python3 that Vim was built
against (PY_VERSION_HEX), and will be useful to check whether the Python
library you are loading in dynamically actually fits it. When built with
stable ABI, it will be the limited ABI version instead
(`Py_LIMITED_API`), which indicates the minimum version of Python 3 the
user should have, rather than the exact match. When stable ABI is used,
we won't be exposing PY_VERSION_HEX in this var because it just doesn't
seem necessary to do so (the whole point of stable ABI is the promise
that it will work across versions), and I don't want to confuse the user
with too many variables.
Also, cleaned up some documentation, and added help tags.
11) Fix Python 3.7 compat issues
Fix a couple issues when using limited API < 3.8
- Crash on exit: In Python 3.7, if a heap-allocated type is destroyed
before all instances are, it would cause a crash later. This happens
when we destroyed `OptionsType` before calling `Py_Finalize` when
using the limited API. To make it worse, later versions changed the
semantics and now each instance has a strong reference to its own type
and the recommendation has changed to have each instance de-ref its
own type and have its type in GC traversal. To avoid dealing with
these cross-version variations, we just don't free the heap type. They
are static types in non-limited-API anyway and are designed to last
through the entirety of the app, and we also don't restart the Python
runtime and therefore do not need it to have absolutely 0 leaks.
See:
- https://docs.python.org/3/whatsnew/3.8.html#changes-in-the-c-api
- https://docs.python.org/3/whatsnew/3.9.html#changes-in-the-c-api
- PyIter_Check: This function is not provided in limited APIs older than
3.8. Previously I was trying to mock it out using manual
PyType_GetSlot() but it was brittle and also does not actually work
properly for static types (it will generate a Python error). Just
return false. It does mean using limited API < 3.8 is not recommended
as you lose the functionality to handle iterators, but from playing
with plugins I couldn't find it to be an issue.
- Fix loading of PyIter_Check so it will be done when limited API < 3.8.
Otherwise loading a 3.7 Python lib will fail even if limited API was
specified to use it.
12) Make sure to only load `PyUnicode_AsUTF8AndSize` in needed in limited API
We don't use this function unless limited API >= 3.10, but we were
loading it regardless. Usually it's ok in Unix-like systems where Python
just has a single lib that we load from, but in Windows where there is a
separate python3.dll this would not work as the symbol would not have
been exposed in this more limited DLL file. This makes it much clearer
under what condition is this function needed.
closes: #12032
Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>
author | Christian Brabandt <cb@256bit.org> |
---|---|
date | Sun, 20 Aug 2023 21:30:04 +0200 |
parents | f8116058ca76 |
children | 4635e43f2c6f |
line wrap: on
line source
*usr_26.txt* For Vim version 9.0. Last change: 2006 Apr 24 VIM USER MANUAL - by Bram Moolenaar Repeating An editing task is hardly ever unstructured. A change often needs to be made several times. In this chapter a number of useful ways to repeat a change will be explained. |26.1| Repeating with Visual mode |26.2| Add and subtract |26.3| Making a change in many files |26.4| Using Vim from a shell script Next chapter: |usr_27.txt| Search commands and patterns Previous chapter: |usr_25.txt| Editing formatted text Table of contents: |usr_toc.txt| ============================================================================== *26.1* Repeating with Visual mode Visual mode is very handy for making a change in any sequence of lines. You can see the highlighted text, thus you can check if the correct lines are changed. But making the selection takes some typing. The "gv" command selects the same area again. This allows you to do another operation on the same text. Suppose you have some lines where you want to change "2001" to "2002" and "2000" to "2001": The financial results for 2001 are better ~ than for 2000. The income increased by 50%, ~ even though 2001 had more rain than 2000. ~ 2000 2001 ~ income 45,403 66,234 ~ First change "2001" to "2002". Select the lines in Visual mode, and use: > :s/2001/2002/g Now use "gv" to reselect the same text. It doesn't matter where the cursor is. Then use ":s/2000/2001/g" to make the second change. Obviously, you can repeat these changes several times. ============================================================================== *26.2* Add and subtract When repeating the change of one number into another, you often have a fixed offset. In the example above, one was added to each year. Instead of typing a substitute command for each year that appears, the CTRL-A command can be used. Using the same text as above, search for a year: > /19[0-9][0-9]\|20[0-9][0-9] Now press CTRL-A. The year will be increased by one: The financial results for 2002 are better ~ than for 2000. The income increased by 50%, ~ even though 2001 had more rain than 2000. ~ 2000 2001 ~ income 45,403 66,234 ~ Use "n" to find the next year, and press "." to repeat the CTRL-A ("." is a bit quicker to type). Repeat "n" and "." for all years that appear. Hint: set the 'hlsearch' option to see the matches you are going to change, then you can look ahead and do it faster. Adding more than one can be done by prepending the number to CTRL-A. Suppose you have this list: 1. item four ~ 2. item five ~ 3. item six ~ Move the cursor to "1." and type: > 3 CTRL-A The "1." will change to "4.". Again, you can use "." to repeat this on the other numbers. Another example: 006 foo bar ~ 007 foo bar ~ Using CTRL-A on these numbers results in: 007 foo bar ~ 010 foo bar ~ 7 plus one is 10? What happened here is that Vim recognized "007" as an octal number, because there is a leading zero. This notation is often used in C programs. If you do not want a number with leading zeros to be handled as octal, use this: > :set nrformats-=octal The CTRL-X command does subtraction in a similar way. ============================================================================== *26.3* Making a change in many files Suppose you have a variable called "x_cnt" and you want to change it to "x_counter". This variable is used in several of your C files. You need to change it in all files. This is how you do it. Put all the relevant files in the argument list: > :args *.c < This finds all C files and edits the first one. Now you can perform a substitution command on all these files: > :argdo %s/\<x_cnt\>/x_counter/ge | update The ":argdo" command takes an argument that is another command. That command will be executed on all files in the argument list. The "%s" substitute command that follows works on all lines. It finds the word "x_cnt" with "\<x_cnt\>". The "\<" and "\>" are used to match the whole word only, and not "px_cnt" or "x_cnt2". The flags for the substitute command include "g" to replace all occurrences of "x_cnt" in the same line. The "e" flag is used to avoid an error message when "x_cnt" does not appear in the file. Otherwise ":argdo" would abort on the first file where "x_cnt" was not found. The "|" separates two commands. The following "update" command writes the file only if it was changed. If no "x_cnt" was changed to "x_counter" nothing happens. There is also the ":windo" command, which executes its argument in all windows. And ":bufdo" executes its argument on all buffers. Be careful with this, because you might have more files in the buffer list than you think. Check this with the ":buffers" command (or ":ls"). ============================================================================== *26.4* Using Vim from a shell script Suppose you have a lot of files in which you need to change the string "-person-" to "Jones" and then print it. How do you do that? One way is to do a lot of typing. The other is to write a shell script to do the work. The Vim editor does a superb job as a screen-oriented editor when using Normal mode commands. For batch processing, however, Normal mode commands do not result in clear, commented command files; so here you will use Ex mode instead. This mode gives you a nice command-line interface that makes it easy to put into a batch file. ("Ex command" is just another name for a command-line (:) command.) The Ex mode commands you need are as follows: > %s/-person-/Jones/g write tempfile quit You put these commands in the file "change.vim". Now to run the editor in batch mode, use this shell script: > for file in *.txt; do vim -e -s $file < change.vim lpr -r tempfile done The for-done loop is a shell construct to repeat the two lines in between, while the $file variable is set to a different file name each time. The second line runs the Vim editor in Ex mode (-e argument) on the file $file and reads commands from the file "change.vim". The -s argument tells Vim to operate in silent mode. In other words, do not keep outputting the :prompt, or any other prompt for that matter. The "lpr -r tempfile" command prints the resulting "tempfile" and deletes it (that's what the -r argument does). READING FROM STDIN Vim can read text on standard input. Since the normal way is to read commands there, you must tell Vim to read text instead. This is done by passing the "-" argument in place of a file. Example: > ls | vim - This allows you to edit the output of the "ls" command, without first saving the text in a file. If you use the standard input to read text from, you can use the "-S" argument to read a script: > producer | vim -S change.vim - NORMAL MODE SCRIPTS If you really want to use Normal mode commands in a script, you can use it like this: > vim -s script file.txt ... < Note: "-s" has a different meaning when it is used without "-e". Here it means to source the "script" as Normal mode commands. When used with "-e" it means to be silent, and doesn't use the next argument as a file name. The commands in "script" are executed like you typed them. Don't forget that a line break is interpreted as pressing <Enter>. In Normal mode that moves the cursor to the next line. To create the script you can edit the script file and type the commands. You need to imagine what the result would be, which can be a bit difficult. Another way is to record the commands while you perform them manually. This is how you do that: > vim -w script file.txt ... All typed keys will be written to "script". If you make a small mistake you can just continue and remember to edit the script later. The "-w" argument appends to an existing script. That is good when you want to record the script bit by bit. If you want to start from scratch and start all over, use the "-W" argument. It overwrites any existing file. ============================================================================== Next chapter: |usr_27.txt| Search commands and patterns Copyright: see |manual-copyright| vim:tw=78:ts=8:noet:ft=help:norl: