_cursesmodule.c callable update_lines_cols()

[nemesis]

BPO	4254
Nosy	@Yhg1s, @bitdancer, @wiggin15, @zooba
Files	_curses.diff: update_lines_cols public accessible manual_test_4254.py issue4254.diff issue4254-1.diff issue4254-2.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2015-05-18.00:51:18.747>
created_at = <Date 2008-11-03.15:02:07.897>
labels = ['extension-modules', 'type-feature']
title = '_cursesmodule.c callable update_lines_cols()'
updated_at = <Date 2015-05-18.00:51:18.745>
user = 'https://bugs.python.org/nemesis'

bugs.python.org fields:

activity = <Date 2015-05-18.00:51:18.745>
actor = 'r.david.murray'
assignee = 'none'
closed = True
closed_date = <Date 2015-05-18.00:51:18.747>
closer = 'r.david.murray'
components = ['Extension Modules']
creation = <Date 2008-11-03.15:02:07.897>
creator = 'nemesis'
dependencies = []
files = ['11932', '38971', '39037', '39044', '39048']
hgrepos = []
issue_num = 4254
keywords = ['patch']
message_count = 18.0
messages = ['75464', '75468', '75470', '75472', '75473', '82782', '82783', '110695', '240793', '241048', '241108', '241115', '241132', '241142', '241164', '241170', '241171', '243441']
nosy_count = 6.0
nosy_names = ['twouters', 'nemesis', 'r.david.murray', 'wiggin15', 'python-dev', 'steve.dower']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue4254'
versions = ['Python 3.5']

[nemesis]

curses.update_lines.cols() are normally usable within c programs. With
this change, it can now be used too. It only calls the preexisting
function that where only used internally. The cast in the return
statement are possibly false? But it works.
Because this aren't a big change, it would apply to some more
python-versions.

[vstinner]

Your function PyCurses_update_lines_cols() has no documentation. Can
you add it?

Can you also give an use case of update_lines_cols()? The function is
already called by curses.resizeterm() and curses.resize_term().

[nemesis]

Hi Victor,

i use this to get updated versions of curses.COLS and curses.LINES in
the fact of an curses.KEY_RESIZE event.
So i can use curses within python even without to have panels.
It seems that curses.panel are the prefered way to deal with terminal
resizes.
The curses.resize[_]term() are only to change the terminal manualy.
What i also found in PyTone is more or less this functionality from
update_lines_cols():

def getmaxyx(self):
    # taken from http://dag.wieers.com/home-made/dstat/
    try:
        h, w = int(os.environ["LINES"]), int(os.environ["COLUMNS"])
    except KeyError:
        try:
            h, w = curses.tigetnum('lines'), curses.tigetnum('cols')
        except:
            try:
                s = struct.pack('HHHH', 0, 0, 0, 0)
                x = fcntl.ioctl(sys.stdout.fileno(), termios.TIOCGWINSZ,
s)
                h, w = struct.unpack('HHHH', x)[:2]
            except:
                h, w = 25, 80

And please excuse me for the missing documentation. English aren't my
native language so i would document it like:
Updates curses.LINES and curses.COLS :)

It's my first day here on the issue tracker.

[vstinner]

i use this to get updated versions of curses.COLS and curses.LINES in
the fact of an curses.KEY_RESIZE event.

I didn't know this event. Is a key in a special keyboard? Or an event raised
by some curses internals?

Updates curses.LINES and curses.COLS

Your documentation is incomplete. You may reused this comment:

/* Internal helper used for updating curses.LINES, curses.COLS,

• _curses.LINES and _curses.COLS */

Oh I just realized that _curses functions have no documentation, great :-/

It's my first day here on the issue tracker.

Welcome on the tracker ;-)

[nemesis]

> i use this to get updated versions of curses.COLS and curses.LINES in
> the fact of an curses.KEY_RESIZE event.

I didn't know this event. Is a key in a special keyboard? Or an event
raised
by some curses internals?
Internal curses event.

Oh I just realized that _curses functions have no documentation,
great :-/
Thats why python_curses should be more compatible to the existing
c_curses documentations.

> It's my first day here on the issue tracker.

Welcome on the tracker ;-)
Thanks.

Any questions? :)

[akuchling]

No documentation? Doc/library/curses.rst exists; there's also
Doc/howto/curses.rst. What functions in _curses need to be documented?

[akuchling]

BTW, the code portion of the patch looks OK to me.

[BreamoreBoy]

msg82783 states code portion of patch looks ok, what do we need to take this forward?

[wiggin15]

Creating an automatic test for this issue proves difficult, as using curses to resize the terminal already updates the values, and using ioctls to try to bypass curses, doesn't work.
I'm adding a manual test program (mostly taken from http://www.gossamer-threads.com/lists/python/python/226137), and a newer patch with documentation.

[bitdancer]

Thanks for the patch update.

The doc addition needs a .. versionadded directive, and there should be an entry in the 3.5 whatsnew document.

[wiggin15]

Fixed David's comments