[Bug 789055] New: Gst.Bin __init__ changed behavior between 1.10 and 1.12 GStreamer version

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=789055

Bug ID: 789055
Summary: Gst.Bin __init__ changed behavior between 1.10 and
1.12 GStreamer version
Classification: Platform
Product: GStreamer
Version: 1.x
OS: Linux
Status: NEW
Severity: major
Priority: Normal
Component: gst-python
Assignee: gstreamer-***@lists.freedesktop.org
Reporter: ***@gmail.com
QA Contact: gstreamer-***@lists.freedesktop.org
GNOME version: ---

In version 1.10 Gst.Bin component behaved like a regular GObject class used in
python. I mean, you could define a new component using Gst.Bin as parent,
define properties as GObject.ParamFlags.CONSTRUCT_ONLY and pass values to
__init__ method in order to set them.

class MyBin(Gst.Bin):
foo = GObject.Property(type=str,
flags=GObject.ParamFlags.CONSTRUCT_ONLY |
GObject.ParamFlags.READWRITE)

def __init__(self, *args, **kwargs):
Gst.Bin.__init__(self, *args, **kwargs)
# your stuff



my_bin = MyBin(foo='bar')

But currently in Gst version 1.12 it raise an error because it does not pass
properties to GObject.Object.__init__.

TypeError: __init__() got an unexpected keyword argument 'foo'

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=789055

Andreu N <***@gmail.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Version|1.x |1.12.x

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=789055

Sebastian Dröge (slomo) <***@coaxion.net> changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |***@coaxion.net

--- Comment #1 from Sebastian Dröge (slomo) <***@coaxion.net> ---
I can't see any change between 1.10.0 and latest 1.12 that looks like it would
be the cause. Can you "git bisect" to find the offending commit?

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=789055

--- Comment #2 from Andreu N <***@gmail.com> ---
I've already reviewed changes between 1.10.x and 1.12.x. And you are right,
there are no (obvious) changes about that. And yet it happens. In fact, I can't
explain why it worked with 1.10.x. Behaviour in 1.12.x looks like regular one
looking at code.

I'm using a dirty workaround in 1.12.x:

class MyBin(Gst.Bin):
foo = GObject.Property(type=str,
flags=GObject.ParamFlags.CONSTRUCT_ONLY |
GObject.ParamFlags.READWRITE)

def __init__(self, *args, **kwargs):
Gst.Element.__init__(self, **kwargs)
Gst.Bin.__init__(self)
# your stuff

Perhaps I'm reserving more memory than I should, and I'm not sure if it will be
freed.

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=789055

--- Comment #3 from Andreu N <***@gmail.com> ---
More info:

In my remote machine (CentOS 7.2):

$ python3.4
Python 3.4.5 (default, May 29 2017, 15:17:55)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux
Type "help", "copyright", "credits" or "license" for more information.

import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst
Gst.version_string()

'GStreamer 1.10.2'

import inspect
inspect.signature(Gst.Bin.__init__).parameters

mappingproxy(OrderedDict([('self', <Parameter at 0x7f637cea4a68 'self'>),
('args', <Parameter at 0x7f637ce97e10 'args'>), ('kwargs', <Parameter at
0x7f637cc176c0 'kwargs'>)]))

Gst.Bin.__mro__

(<class 'gi.repository.Gst.Bin'>, <class 'gi.repository.Gst.Element'>, <class
'gi.repository.Gst.Object'>, <class 'gi.repository.GObject.InitiallyUnowned'>,
<class 'gi.overrides.GObject.Object'>, <class 'gi.repository.GObject.Object'>,
<class 'gi._gobject.GObject'>, <class 'gi.repository.Gst.ChildProxy'>, <class
'gobject.GInterface'>, <class 'object'>)


It looks like Gst.Bin is not overridden. It's weird because it is overridden
since commit 02ca5d3ad25 (5 years ago). On the other hand, I don't understand
why __init__ method must be overridden.

In my labtop (Fedora 26):

$ python3
Python 3.6.2 (default, Oct 2 2017, 16:51:32)
[GCC 7.2.1 20170915 (Red Hat 7.2.1-2)] on linux
Type "help", "copyright", "credits" or "license" for more information.

import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst
Gst.init([])

[]

Gst.version_string()

'GStreamer 1.12.3'

import inspect
inspect.signature(Gst.Bin.__init__).parameters

mappingproxy(OrderedDict([('self', <Parameter "self">), ('name', <Parameter
"name=None">)]))

Gst.Bin.__mro__

(<class 'gi.overrides.Gst.Bin'>, <class 'gi.repository.Gst.Bin'>, <class
'gi.repository.Gst.Element'>, <class 'gi.repository.Gst.Object'>, <class
'gi.repository.GObject.InitiallyUnowned'>, <class
'gi.overrides.GObject.Object'>, <class 'gi.repository.GObject.Object'>, <class
'gi._gobject.GObject'>, <class 'gi.repository.Gst.ChildProxy'>, <class
'gobject.GInterface'>, <class 'object'>)

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=789055

Tim-Philipp Müller <***@zen.co.uk> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |NEEDINFO
CC| |***@zen.co.uk

--- Comment #4 from Tim-Philipp Müller <***@zen.co.uk> ---
Could this be caused by different versions of g-i/pygi or the presence/absence
of gst-python?

On my debian sid:

$ python3
Python 3.6.4 (default, Jan 5 2018, 02:13:53)

inspect.signature(Gst.Bin.__init__).parameters

mappingproxy(OrderedDict([('self', <Parameter "self">), ('args', <Parameter
"*args">), ('kwargs', <Parameter "**kwargs">)]))

Gst.Bin.__mro__

(<class 'gi.repository.Gst.Bin'>, <class 'gi.repository.Gst.Element'>, <class
'gi.repository.Gst.Object'>, <class 'gi.repository.GObject.InitiallyUnowned'>,
<class 'gi.overrides.GObject.Object'>, <class 'gi.repository.GObject.Object'>,
<class 'gi._gi.GObject'>, <class 'gi.repository.Gst.ChildProxy'>, <class
'gobject.GInterface'>, <class 'object'>)

Gst.version_string()

'GStreamer 1.12.4'

python-gi is 3.26.1-2

python-gst-1.0 is not installed

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=789055

--- Comment #5 from Andreu N <***@gmail.com> ---
Neither on my labtop or remote machine, python-gst is installed.

Curiously, you are getting same bug on version 1.12 than me on version 1.10.
The problem is in class <class 'gi.overrides.Gst.Bin'>. Looking at code it
looks python-gi is overriding Bin base class (I don't know why it is needed).
https://cgit.freedesktop.org/gstreamer/gst-python/tree/gi/overrides/Gst.py#n65

I guess there was a problem with function `override` from python-gi. But it was
solved in with a refactor
(https://gitlab.gnome.org/GNOME/pygobject/commit/149c31beced944c72fba6ca6e096c81c1100ea2b).

So, in brief, gst-python (gi) was using function override from pygobject but it
wasn't worked properly. Now it works but gst-python implementation prevents to
set construct-only properties in custom Bin classes.

From my point of view, it should be solved on gst-python doing something like:

```
File: gi/overrides/Gst.py
Line: 56

class Bin(Gst.Bin):
def __init__(self, name=None, **kwargs):
Gst.Bin.__init__(self, name=name, **kwargs)

def add(self, *args):
for arg in args:
if not Gst.Bin.add(self, arg):
raise AddError(arg)
```

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=789055

import gi
gi.version_info

(3, 26, 1)

import gi
gi.version_info

(3, 18, 2)

["GStreamer" (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=789055

GStreamer system administrator <***@gstreamer.net> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|NEEDINFO |RESOLVED
Resolution|--- |OBSOLETE

--- Comment #7 from GStreamer system administrator <***@gstreamer.net> ---
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