view runtime/doc/usr_25.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_25.txt*	For Vim version 9.0.  Last change: 2016 Mar 28

		     VIM USER MANUAL - by Bram Moolenaar

			     Editing formatted text


Text hardly ever comes in one sentence per line.  This chapter is about
breaking sentences to make them fit on a page and other formatting.
Vim also has useful features for editing single-line paragraphs and tables.

|25.1|	Breaking lines
|25.2|	Aligning text
|25.3|	Indents and tabs
|25.4|	Dealing with long lines
|25.5|	Editing tables

     Next chapter: |usr_26.txt|  Repeating
 Previous chapter: |usr_24.txt|  Inserting quickly
Table of contents: |usr_toc.txt|

==============================================================================
*25.1*	Breaking lines

Vim has a number of functions that make dealing with text easier.  By default,
the editor does not perform automatic line breaks.  In other words, you have
to press <Enter> yourself.  This is useful when you are writing programs where
you want to decide where the line ends.  It is not so good when you are
creating documentation and want the text to be at most 70 character wide.
   If you set the 'textwidth' option, Vim automatically inserts line breaks.
Suppose, for example, that you want a very narrow column of only 30
characters.  You need to execute the following command: >

	:set textwidth=30

Now you start typing (ruler added):

		 1	   2	     3
	12345678901234567890123456789012345
	I taught programming for a whi ~

If you type "l" next, this makes the line longer than the 30-character limit.
When Vim sees this, it inserts a line break and you get the following:

		 1	   2	     3
	12345678901234567890123456789012345
	I taught programming for a ~
	whil ~

Continuing on, you can type in the rest of the paragraph:

		 1	   2	     3
	12345678901234567890123456789012345
	I taught programming for a ~
	while. One time, I was stopped ~
	by the Fort Worth police, ~
	because my homework was too ~
	hard. True story. ~

You do not have to type newlines; Vim puts them in automatically.

	Note:
	The 'wrap' option makes Vim display lines with a line break, but this
	doesn't insert a line break in the file.


REFORMATTING

The Vim editor is not a word processor.  In a word processor, if you delete
something at the beginning of the paragraph, the line breaks are reworked.  In
Vim they are not; so if you delete the word "programming" from the first line,
all you get is a short line:

		 1	   2	     3
	12345678901234567890123456789012345
	I taught for a ~
	while. One time, I was stopped ~
	by the Fort Worth police, ~
	because my homework was too ~
	hard. True story. ~

This does not look good.  To get the paragraph into shape you use the "gq"
operator.
   Let's first use this with a Visual selection.  Starting from the first
line, type: >

	v4jgq

"v" to start Visual mode, "4j" to move to the end of the paragraph and then
the "gq" operator.  The result is:

		 1	   2	     3
	12345678901234567890123456789012345
	I taught for a while. One ~
	time, I was stopped by the ~
	Fort Worth police, because my ~
	homework was too hard. True ~
	story. ~

Note: there is a way to do automatic formatting for specific types of text
layouts, see |auto-format|.

Since "gq" is an operator, you can use one of the three ways to select the
text it works on: With Visual mode, with a movement and with a text object.
   The example above could also be done with "gq4j".  That's less typing, but
you have to know the line count.  A more useful motion command is "}".  This
moves to the end of a paragraph.  Thus "gq}" formats from the cursor to the
end of the current paragraph.
   A very useful text object to use with "gq" is the paragraph.  Try this: >

	gqap

"ap" stands for "a-paragraph".  This formats the text of one paragraph
(separated by empty lines).  Also the part before the cursor.
   If you have your paragraphs separated by empty lines, you can format the
whole file by typing this: >

	gggqG

"gg" to move to the first line, "gqG" to format until the last line.
   Warning: If your paragraphs are not properly separated, they will be joined
together.  A common mistake is to have a line with a space or tab.  That's a
blank line, but not an empty line.

Vim is able to format more than just plain text.  See |fo-table| for how to
change this.  See the 'joinspaces' option to change the number of spaces used
after a full stop.
   It is possible to use an external program for formatting.  This is useful
if your text can't be properly formatted with Vim's builtin command.  See the
'formatprg' option.

==============================================================================
*25.2*	Aligning text

To center a range of lines, use the following command: >

	:{range}center [width]

{range} is the usual command-line range.  [width] is an optional line width to
use for centering.  If [width] is not specified, it defaults to the value of
'textwidth'.  (If 'textwidth' is 0, the default is 80.)
   For example: >

	:1,5center 40

results in the following:

       I taught for a while. One ~
       time, I was stopped by the ~
     Fort Worth police, because my ~
      homework was too hard. True ~
		 story. ~


RIGHT ALIGNMENT

Similarly, the ":right" command right-justifies the text: >

	:1,5right 37

gives this result:

	    I taught for a while. One ~
	   time, I was stopped by the ~
	Fort Worth police, because my ~
	  homework was too hard. True ~
			       story. ~

LEFT ALIGNMENT

Finally there is this command: >

	:{range}left [margin]

Unlike ":center" and ":right", however, the argument to ":left" is not the
length of the line.  Instead it is the left margin.  If it is omitted, the
text will be put against the left side of the screen (using a zero margin
would do the same).  If it is 5, the text will be indented 5 spaces.  For
example, use these commands: >

	:1left 5
	:2,5left

This results in the following:

	     I taught for a while. One ~
	time, I was stopped by the ~
	Fort Worth police, because my ~
	homework was too hard. True ~
	story. ~


JUSTIFYING TEXT

Vim has no built-in way of justifying text.  However, there is a neat macro
package that does the job.  To use this package, execute the following
command: >

	:packadd justify

Or put this line in your |vimrc|: >

	packadd! justify

This Vim script file defines a new visual command "_j".  To justify a block of
text, highlight the text in Visual mode and then execute "_j".
   Look in the file for more explanations.  To go there, do "gf" on this name:
$VIMRUNTIME/pack/dist/opt/justify/plugin/justify.vim.

An alternative is to filter the text through an external program.  Example: >

	:%!fmt

==============================================================================
*25.3*	Indents and tabs

Indents can be used to make text stand out from the rest.  The example texts
in this manual, for example, are indented by eight spaces or a tab.  You would
normally enter this by typing a tab at the start of each line.  Take this
text:
	the first line ~
	the second line ~

This is entered by typing a tab, some text, <Enter>, tab and more text.
   The 'autoindent' option inserts indents automatically: >

	:set autoindent

When a new line is started it gets the same indent as the previous line.  In
the above example, the tab after the <Enter> is not needed anymore.


INCREASING INDENT

To increase the amount of indent in a line, use the ">" operator.  Often this
is used as ">>", which adds indent to the current line.
   The amount of indent added is specified with the 'shiftwidth' option.  The
default value is 8.  To make ">>" insert four spaces worth of indent, for
example, type this: >

	:set shiftwidth=4

When used on the second line of the example text, this is what you get:

	the first line ~
	    the second line ~

"4>>" will increase the indent of four lines.


TABSTOP

If you want to make indents a multiple of 4, you set 'shiftwidth' to 4.  But
when pressing a <Tab> you still get 8 spaces worth of indent.  To change this,
set the 'softtabstop' option: >

	:set softtabstop=4

This will make the <Tab> key insert 4 spaces worth of indent.  If there are
already four spaces, a <Tab> character is used (saving seven characters in the
file).  (If you always want spaces and no tab characters, set the 'expandtab'
option.)

	Note:
	You could set the 'tabstop' option to 4.  However, if you edit the
	file another time, with 'tabstop' set to the default value of 8, it
	will look wrong.  In other programs and when printing the indent will
	also be wrong.  Therefore it is recommended to keep 'tabstop' at eight
	all the time.  That's the standard value everywhere.


CHANGING TABS

You edit a file which was written with a tabstop of 3.  In Vim it looks ugly,
because it uses the normal tabstop value of 8.  You can fix this by setting
'tabstop' to 3.  But you have to do this every time you edit this file.
   Vim can change the use of tabstops in your file.  First, set 'tabstop' to
make the indents look good, then use the ":retab" command: >

	:set tabstop=3
	:retab 8

The ":retab" command will change 'tabstop' to 8, while changing the text such
that it looks the same.  It changes spans of white space into tabs and spaces
for this.  You can now write the file.  Next time you edit it the indents will
be right without setting an option.
   Warning: When using ":retab" on a program, it may change white space inside
a string constant.  Therefore it's a good habit to use "\t" instead of a
real tab.

==============================================================================
*25.4*	Dealing with long lines

Sometimes you will be editing a file that is wider than the number of columns
in the window.  When that occurs, Vim wraps the lines so that everything fits
on the screen.
   If you switch the 'wrap' option off, each line in the file shows up as one
line on the screen.  Then the ends of the long lines disappear off the screen
to the right.
   When you move the cursor to a character that can't be seen, Vim will scroll
the text to show it.  This is like moving a viewport over the text in the
horizontal direction.
   By default, Vim does not display a horizontal scrollbar in the GUI.  If you
want to enable one, use the following command: >

	:set guioptions+=b

One horizontal scrollbar will appear at the bottom of the Vim window.

If you don't have a scrollbar or don't want to use it, use these commands to
scroll the text.  The cursor will stay in the same place, but it's moved back
into the visible text if necessary.

	zh		scroll right
	4zh		scroll four characters right
	zH		scroll half a window width right
	ze		scroll right to put the cursor at the end
	zl		scroll left
	4zl		scroll four characters left
	zL		scroll half a window width left
	zs		scroll left to put the cursor at the start

Let's attempt to show this with one line of text.  The cursor is on the "w" of
"which".  The "current window" above the line indicates the text that is
currently visible.  The "window"s below the text indicate the text that is
visible after the command left of it.

			      |<-- current window -->|
		some long text, part of which is visible in the window ~
	ze	  |<--	   window     -->|
	zH	   |<--     window     -->|
	4zh		  |<--	   window     -->|
	zh		     |<--     window	 -->|
	zl		       |<--	window	   -->|
	4zl			  |<--	   window     -->|
	zL				|<--	 window     -->|
	zs			       |<--	window	   -->|


MOVING WITH WRAP OFF

When 'wrap' is off and the text has scrolled horizontally, you can use the
following commands to move the cursor to a character you can see.  Thus text
left and right of the window is ignored.  These never cause the text to
scroll:

	g0		to first visible character in this line
	g^		to first non-blank visible character in this line
	gm		to middle of screen line
	gM		to middle of the text in this line
	g$		to last visible character in this line

		|<--	  window     -->|
	some long    text, part of which is visible in one line ~
		 g0  g^    gm	   gM g$


BREAKING AT WORDS				*edit-no-break*

When preparing text for use by another program, you might have to make
paragraphs without a line break.  A disadvantage of using 'nowrap' is that you
can't see the whole sentence you are working on.  When 'wrap' is on, words are
broken halfway, which makes them hard to read.
   A good solution for editing this kind of paragraph is setting the
'linebreak' option.  Vim then breaks lines at an appropriate place when
displaying the line.  The text in the file remains unchanged.
   Without 'linebreak' text might look like this:

	+---------------------------------+
	|letter generation program for a b|
	|ank.  They wanted to send out a s|
	|pecial, personalized letter to th|
	|eir richest 1000 customers.  Unfo|
	|rtunately for the programmer, he |
	+---------------------------------+
After: >

	:set linebreak

it looks like this:

	+---------------------------------+
	|letter generation program for a  |
	|bank.  They wanted to send out a |
	|special, personalized letter to  |
	|their richest 1000 customers.    |
	|Unfortunately for the programmer,|
	+---------------------------------+

Related options:
'breakat' specifies the characters where a break can be inserted.
'showbreak' specifies a string to show at the start of broken line.
Set 'textwidth' to zero to avoid a paragraph to be split.


MOVING BY VISIBLE LINES

The "j" and "k" commands move to the next and previous lines.  When used on
a long line, this means moving a lot of screen lines at once.
   To move only one screen line, use the "gj" and "gk" commands.  When a line
doesn't wrap they do the same as "j" and "k".  When the line does wrap, they
move to a character displayed one line below or above.
   You might like to use these mappings, which bind these movement commands to
the cursor keys: >

	:map <Up> gk
	:map <Down> gj


TURNING A PARAGRAPH INTO ONE LINE			*edit-paragraph-join*

If you want to import text into a program like MS-Word, each paragraph should
be a single line.  If your paragraphs are currently separated with empty
lines, this is how you turn each paragraph into a single line: >

	:g/./,/^$/join

That looks complicated.  Let's break it up in pieces:

	:g/./		A ":global" command that finds all lines that contain
			at least one character.
	     ,/^$/	A range, starting from the current line (the non-empty
			line) until an empty line.
		  join	The ":join" command joins the range of lines together
			into one line.

Starting with this text, containing eight lines broken at column 30:

	+----------------------------------+
	|A letter generation program	   |
	|for a bank.  They wanted to	   |
	|send out a special,		   |
	|personalized letter.		   |
	|				   |
	|To their richest 1000		   |
	|customers.  Unfortunately for	   |
	|the programmer,		   |
	+----------------------------------+

You end up with two lines:

	+----------------------------------+
	|A letter generation program for a |
	|bank.	They wanted to send out a s|
	|pecial, personalized letter.	   |
	|To their richest 1000 customers.  |
	|Unfortunately for the programmer, |
	+----------------------------------+

Note that this doesn't work when the separating line is blank but not empty;
when it contains spaces and/or tabs.  This command does work with blank lines:
>
	:g/\S/,/^\s*$/join

This still requires a blank or empty line at the end of the file for the last
paragraph to be joined.

==============================================================================
*25.5*	Editing tables

Suppose you are editing a table with four columns:

	nice table	  test 1	test 2	    test 3 ~
	input A		  0.534 ~
	input B		  0.913 ~

You need to enter numbers in the third column.  You could move to the second
line, use "A", enter a lot of spaces and type the text.
   For this kind of editing there is a special option: >

	set virtualedit=all

Now you can move the cursor to positions where there isn't any text.  This is
called "virtual space".  Editing a table is a lot easier this way.
   Move the cursor by searching for the header of the last column: >

	/test 3

Now press "j" and you are right where you can enter the value for "input A".
Typing "0.693" results in:

	nice table	  test 1     test 2	 test 3 ~
	input A		  0.534			 0.693 ~
	input B		  0.913 ~

Vim has automatically filled the gap in front of the new text for you.  Now,
to enter the next field in this column use "Bj".  "B" moves back to the start
of a white space separated word.  Then "j" moves to the place where the next
field can be entered.

	Note:
	You can move the cursor anywhere in the display, also beyond the end
	of a line.  But Vim will not insert spaces there, until you insert a
	character in that position.


COPYING A COLUMN

You want to add a column, which should be a copy of the third column and
placed before the "test 1" column.  Do this in seven steps:
1.  Move the cursor to the left upper corner of this column, e.g., with
    "/test 3".
2.  Press CTRL-V to start blockwise Visual mode.
3.  Move the cursor down two lines with "2j".  You are now in "virtual space":
    the "input B" line of the "test 3" column.
4.  Move the cursor right, to include the whole column in the selection, plus
    the space that you want between the columns.  "9l" should do it.
5.  Yank the selected rectangle with "y".
6.  Move the cursor to "test 1", where the new column must be placed.
7.  Press "P".

The result should be:

	nice table	  test 3    test 1     test 2	   test 3 ~
	input A		  0.693     0.534		   0.693 ~
	input B			    0.913 ~

Notice that the whole "test 1" column was shifted right, also the line where
the "test 3" column didn't have text.

Go back to non-virtual cursor movements with: >

	:set virtualedit=


VIRTUAL REPLACE MODE

The disadvantage of using 'virtualedit' is that it "feels" different.  You
can't recognize tabs or spaces beyond the end of line when moving the cursor
around.  Another method can be used: Virtual Replace mode.
   Suppose you have a line in a table that contains both tabs and other
characters.  Use "rx" on the first tab:

	inp	0.693   0.534	0.693 ~

	       |
	   rx  |
	       V

	inpx0.693   0.534	0.693 ~

The layout is messed up.  To avoid that, use the "gr" command:

	inp	0.693   0.534	0.693 ~

	       |
	  grx  |
	       V

	inpx	0.693   0.534	0.693 ~

What happens is that the "gr" command makes sure the new character takes the
right amount of screen space.  Extra spaces or tabs are inserted to fill the
gap.  Thus what actually happens is that a tab is replaced by "x" and then
blanks added to make the text after it keep its place.  In this case a
tab is inserted.
   When you need to replace more than one character, you use the "R" command
to go to Replace mode (see |04.9|).  This messes up the layout and replaces
the wrong characters:

	inp	0	0.534	0.693 ~

		|
	 R0.786 |
		V

	inp	0.78634	0.693 ~

The "gR" command uses Virtual Replace mode.  This preserves the layout:

	inp	0	0.534	0.693 ~

		|
	gR0.786 |
		V

	inp	0.786	0.534	0.693 ~

==============================================================================

Next chapter: |usr_26.txt|  Repeating

Copyright: see |manual-copyright|  vim:tw=78:ts=8:noet:ft=help:norl: