Mercurial > vim
view runtime/doc/usr_20.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_20.txt* For Vim version 9.0. Last change: 2021 Nov 18 VIM USER MANUAL - by Bram Moolenaar Typing command-line commands quickly Vim has a few generic features that makes it easier to enter commands. Colon commands can be abbreviated, edited and repeated. Completion is available for nearly everything. |20.1| Command line editing |20.2| Command line abbreviations |20.3| Command line completion |20.4| Command line history |20.5| Command line window Next chapter: |usr_21.txt| Go away and come back Previous chapter: |usr_12.txt| Clever tricks Table of contents: |usr_toc.txt| ============================================================================== *20.1* Command line editing When you use a colon (:) command or search for a string with / or ?, Vim puts the cursor on the bottom of the screen. There you type the command or search pattern. This is called the Command line. Also when it's used for entering a search command. The most obvious way to edit the command you type is by pressing the <BS> key. This erases the character before the cursor. To erase another character, typed earlier, first move the cursor with the cursor keys. For example, you have typed this: > :s/col/pig/ Before you hit <Enter>, you notice that "col" should be "cow". To correct this, you type <Left> five times. The cursor is now just after "col". Type <BS> and "w" to correct: > :s/cow/pig/ Now you can press <Enter> directly. You don't have to move the cursor to the end of the line before executing the command. The most often used keys to move around in the command line: <Left> one character left <Right> one character right <S-Left> or <C-Left> one word left <S-Right> or <C-Right> one word right CTRL-B or <Home> to begin of command line CTRL-E or <End> to end of command line Note: <S-Left> (cursor left key with Shift key pressed) and <C-Left> (cursor left key with Control pressed) will not work on all keyboards. Same for the other Shift and Control combinations. You can also use the mouse to move the cursor. DELETING As mentioned, <BS> deletes the character before the cursor. To delete a whole word use CTRL-W. /the fine pig ~ CTRL-W /the fine ~ CTRL-U removes all text, thus allows you to start all over again. OVERSTRIKE The <Insert> key toggles between inserting characters and replacing the existing ones. Start with this text: /the fine pig ~ Move the cursor to the start of "fine" with <S-Left> twice (or <Left> eight times, if <S-Left> doesn't work). Now press <Insert> to switch to overstrike and type "great": /the greatpig ~ Oops, we lost the space. Now, don't use <BS>, because it would delete the "t" (this is different from Replace mode). Instead, press <Insert> to switch from overstrike to inserting, and type the space: /the great pig ~ CANCELLING You thought of executing a : or / command, but changed your mind. To get rid of what you already typed, without executing it, press CTRL-C or <Esc>. Note: <Esc> is the universal "get out" key. Unfortunately, in the good old Vi pressing <Esc> in a command line executed the command! Since that might be considered to be a bug, Vim uses <Esc> to cancel the command. But with the 'cpoptions' option it can be made Vi compatible. And when using a mapping (which might be written for Vi) <Esc> also works Vi compatible. Therefore, using CTRL-C is a method that always works. If you are at the start of the command line, pressing <BS> will cancel the command. It's like deleting the ":" or "/" that the line starts with. ============================================================================== *20.2* Command line abbreviations Some of the ":" commands are really long. We already mentioned that ":substitute" can be abbreviated to ":s". This is a generic mechanism, all ":" commands can be abbreviated. How short can a command get? There are 26 letters, and many more commands. For example, ":set" also starts with ":s", but ":s" doesn't start a ":set" command. Instead ":set" can be abbreviated to ":se". When the shorter form of a command could be used for two commands, it stands for only one of them. There is no logic behind which one, you have to learn them. In the help files the shortest form that works is mentioned. For example: > :s[ubstitute] This means that the shortest form of ":substitute" is ":s". The following characters are optional. Thus ":su" and ":sub" also work. In the user manual we will either use the full name of command, or a short version that is still readable. For example, ":function" can be abbreviated to ":fu". But since most people don't understand what that stands for, we will use ":fun". (Vim doesn't have a ":funny" command, otherwise ":fun" would be confusing too.) It is recommended that in Vim scripts you write the full command name. That makes it easier to read back when you make later changes. Except for some often used commands like ":w" (":write") and ":r" (":read"). A particularly confusing one is ":end", which could stand for ":endif", ":endwhile" or ":endfunction". Therefore, always use the full name. SHORT OPTION NAMES In the user manual the long version of the option names is used. Many options also have a short name. Unlike ":" commands, there is only one short name that works. For example, the short name of 'autoindent' is 'ai'. Thus these two commands do the same thing: > :set autoindent :set ai You can find the full list of long and short names here: |option-list|. ============================================================================== *20.3* Command line completion This is one of those Vim features that, by itself, is a reason to switch from Vi to Vim. Once you have used this, you can't do without. Suppose you have a directory that contains these files: info.txt intro.txt bodyofthepaper.txt To edit the last one, you use the command: > :edit bodyofthepaper.txt It's easy to type this wrong. A much quicker way is: > :edit b<Tab> Which will result in the same command. What happened? The <Tab> key does completion of the word before the cursor. In this case "b". Vim looks in the directory and finds only one file that starts with a "b". That must be the one you are looking for, thus Vim completes the file name for you. Now type: > :edit i<Tab> Vim will beep, and give you: > :edit info.txt The beep means that Vim has found more than one match. It then uses the first match it found (alphabetically). If you press <Tab> again, you get: > :edit intro.txt Thus, if the first <Tab> doesn't give you the file you were looking for, press it again. If there are more matches, you will see them all, one at a time. If you press <Tab> on the last matching entry, you will go back to what you first typed: > :edit i Then it starts all over again. Thus Vim cycles through the list of matches. Use CTRL-P to go through the list in the other direction: <------------------- <Tab> -------------------------+ | <Tab> --> <Tab> --> :edit i :edit info.txt :edit intro.txt <-- CTRL-P <-- CTRL-P | +---------------------- CTRL-P ------------------------> CONTEXT When you type ":set i" instead of ":edit i" and press <Tab> you get: > :set icon Hey, why didn't you get ":set info.txt"? That's because Vim has context sensitive completion. The kind of words Vim will look for depends on the command before it. Vim knows that you cannot use a file name just after a ":set" command, but you can use an option name. Again, if you repeat typing the <Tab>, Vim will cycle through all matches. There are quite a few, it's better to type more characters first: > :set isk<Tab> Gives: > :set iskeyword Now type "=" and press <Tab>: > :set iskeyword=@,48-57,_,192-255 What happens here is that Vim inserts the old value of the option. Now you can edit it. What is completed with <Tab> is what Vim expects in that place. Just try it out to see how it works. In some situations you will not get what you want. That's either because Vim doesn't know what you want, or because completion was not implemented for that situation. In that case you will get a <Tab> inserted (displayed as ^I). LIST MATCHES When there are many matches, you would like to see an overview. Do this by pressing CTRL-D. For example, pressing CTRL-D after: > :set is results in: > :set is incsearch isfname isident iskeyword isprint :set is Vim lists the matches and then comes back with the text you typed. You can now check the list for the item you wanted. If it isn't there, you can use <BS> to correct the word. If there are many matches, type a few more characters before pressing <Tab> to complete the rest. If you have watched carefully, you will have noticed that "incsearch" doesn't start with "is". In this case "is" stands for the short name of "incsearch". (Many options have a short and a long name.) Vim is clever enough to know that you might have wanted to expand the short name of the option into the long name. THERE IS MORE The CTRL-L command completes the word to the longest unambiguous string. If you type ":edit i" and there are files "info.txt" and "info_backup.txt" you will get ":edit info". The 'wildmode' option can be used to change the way completion works. The 'wildmenu' option can be used to get a menu-like list of matches. Use the 'suffixes' option to specify files that are less important and appear at the end of the list of files. The 'wildignore' option specifies files that are not listed at all. More about all of this here: |cmdline-completion| ============================================================================== *20.4* Command line history In chapter 3 we briefly mentioned the history. The basics are that you can use the <Up> key to recall an older command line. <Down> then takes you back to newer commands. There are actually five histories. The ones we will mention here are for ":" commands and for "/" and "?" search commands. The "/" and "?" commands share the same history, because they are both search commands. The three other histories are for expressions, debug mode commands and input lines for the input() function. |cmdline-history| Suppose you have done a ":set" command, typed ten more colon commands and then want to repeat that ":set" command again. You could press ":" and then ten times <Up>. There is a quicker way: > :se<Up> Vim will now go back to the previous command that started with "se". You have a good chance that this is the ":set" command you were looking for. At least you should not have to press <Up> very often (unless ":set" commands is all you have done). The <Up> key will use the text typed so far and compare it with the lines in the history. Only matching lines will be used. If you do not find the line you were looking for, use <Down> to go back to what you typed and correct that. Or use CTRL-U to start all over again. To see all the lines in the history: > :history That's the history of ":" commands. The search history is displayed with this command: > :history / CTRL-P will work like <Up>, except that it doesn't matter what you already typed. Similarly for CTRL-N and <Down>. CTRL-P stands for previous, CTRL-N for next. ============================================================================== *20.5* Command line window Typing the text in the command line works differently from typing text in Insert mode. It doesn't allow many commands to change the text. For most commands that's OK, but sometimes you have to type a complicated command. That's where the command line window is useful. Open the command line window with this command: > q: Vim now opens a (small) window at the bottom. It contains the command line history, and an empty line at the end: +-------------------------------------+ |other window | |~ | |file.txt=============================| |:e c | |:e config.h.in | |:set path=.,/usr/include,, | |:set iskeyword=@,48-57,_,192-255 | |:set is | |:q | |: | |command-line=========================| | | +-------------------------------------+ You are now in Normal mode. You can use the "hjkl" keys to move around. For example, move up with "5k" to the ":e config.h.in" line. Type "$h" to go to the "i" of "in" and type "cwout". Now you have changed the line to: :e config.h.out ~ Now press <Enter> and this command will be executed. The command line window will close. The <Enter> command will execute the line under the cursor. It doesn't matter whether Vim is in Insert mode or in Normal mode. Changes in the command line window are lost. They do not result in the history to be changed. Except that the command you execute will be added to the end of the history, like with all executed commands. The command line window is very useful when you want to have overview of the history, lookup a similar command, change it a bit and execute it. A search command can be used to find something. In the previous example the "?config" search command could have been used to find the previous command that contains "config". It's a bit strange, because you are using a command line to search in the command line window. While typing that search command you can't open another command line window, there can be only one. ============================================================================== Next chapter: |usr_21.txt| Go away and come back Copyright: see |manual-copyright| vim:tw=78:ts=8:noet:ft=help:norl: