Re: fixing framework bindings at runtime

Ronald Oussoren via Pyobjc-dev <[email protected]> Sun, 24 May 2020 15:35:57 +0200
Newsgroups gmane.comp.python.pyobjc.devel
Message-ID <[email protected]>
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Hi,

Sorry about the bad news, but=E2=80=A6

The version of PyObjC shipped with macOS is ancient and unsupported, and =
its framework bindings aren=E2=80=99t based on upstream code. Not only =
that, but macOS has never shipped with good data in BridgeSupport files =
and that has gotten worse in the last couple of releases (which is why =
upstream PyObjC has never used these files). =20

The only good solution is to switch to a current version of PyObjC (and =
Python).  That should work and has tests for the bindings.

That said, it might be possible to use the manual binding system =
implement the minimal set of metadata needed for your script.  I can=E2=80=
=99t recall which parts of that system were implemented in the version =
of PyObjC that Apple ships.=20

Ronald
=E2=80=94

Twitter / micro.blog: @ronaldoussoren
Blog: https://blog.ronaldoussoren.net/

> On 24 May 2020, at 12:09, [email protected] wrote:
>=20
> hello,
>=20
> I use pyobjc bindings to build an application that is distributed [0].
> Unfortunately, I have to rely on the Apple provided versions of =
python/pyobjc (2.7.16/2.5.1 on catalina).
> On Catalina, importing the AVFoundation framework leads to a runtime =
warning (Error parsing BridgeSupport data for AVFoundation), see below:
>=20
>    %python  =20
>    Python 2.7.16 (default, Feb 29 2020, 01:55:37)=20
>    [GCC 4.2.1 Compatible Apple LLVM 11.0.3 (clang-1103.0.29.20) =
(-macos10.15-objc- on darwin
>    Type "help", "copyright", "credits" or "license" for more =
information.
>>>> import objc
>>>> objc.__version__
>    '2.5.1'
>>>> import AVFoundation
>    =
/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python=
/PyObjC/objc/_bridgesupport.py:674: RuntimeWarning: Error parsing =
BridgeSupport data for AVFoundation: PyObjCRT_SkipTypeSpec: Unhandled =
type '5d' ]}
>      warnings.warn("Error parsing BridgeSupport data for %s: %s" % =
(frameworkName, e), RuntimeWarning)
>=20
> As a consequence, many things are not loaded properly.
> For example constants are missing (I can fix that by declaring the =
constants in my code).
> But I have a problem that I could not manage to fix myself:
> Methods that take a callback as parameter, like =
AVCaptureDevice.requestAccessForMediaType_completionHandler_, fail with =
a type error (Argument 3 is a block, but no signature available):
>=20
>>>> AVMediaTypeVideo =3D "vide"
>>>> from Foundation import NSObject
>>>> class Test(NSObject):
>    ...   def test_(self, granted):
>    ...     print(granted)
>    ...=20
>>>> test =3D Test.alloc().init()
>>>> =
AVFoundation.AVCaptureDevice.requestAccessForMediaType_completionHandler_(=

>    ...   AVMediaTypeVideo,
>    ...   test.test_)
>    Traceback (most recent call last):
>      File "<stdin>", line 3, in <module>
>    TypeError: Argument 3 is a block, but no signature available
>=20
>>>> test.test_.signature
>    'v@:@'
>>>> =
AVFoundation.AVCaptureDevice.requestAccessForMediaType_completionHandler_.=
signature
>    'v32@0:8@16@?24'
>=20
> Any idea on how to fix this problem without altering the default =
python/pyobjc installation?
> Thanks a lot for any suggestion,
>=20
> Renaud
>=20
> 0. Pr=C3=A9sentation.app
> http://iihm.imag.fr/blanch/software/osx-presentation/
>=20
> _______________________________________________
> Pyobjc-dev mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/pyobjc-dev


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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;" class=3D""><div =
class=3D"">Hi,</div><div class=3D""><br class=3D""></div><div =
class=3D"">Sorry about the bad news, but=E2=80=A6</div><div class=3D""><br=
 class=3D""></div>The version of PyObjC shipped with macOS is ancient =
and unsupported, and its framework bindings aren=E2=80=99t based on =
upstream code. Not only that, but macOS has never shipped with good data =
in BridgeSupport files and that has gotten worse in the last couple of =
releases (which is why upstream PyObjC has never used these files). =
&nbsp;<div class=3D""><br class=3D""></div><div class=3D"">The only good =
solution is to switch to a current version of PyObjC (and Python). =
&nbsp;That should work and has tests for the bindings.<div class=3D""><br =
class=3D""></div><div class=3D"">That said, it might be possible to use =
the manual binding system implement the minimal set of metadata needed =
for your script. &nbsp;I can=E2=80=99t recall which parts of that system =
were implemented in the version of PyObjC that Apple =
ships.&nbsp;</div><div class=3D""><div class=3D""><br =
class=3D""></div><div class=3D"">Ronald<br class=3D""><div class=3D"">
<div dir=3D"auto" style=3D"word-wrap: break-word; -webkit-nbsp-mode: =
space; line-break: after-white-space;" class=3D""><div =
style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: =
Helvetica; font-size: 12px; font-style: normal; font-variant-caps: =
normal; font-weight: normal; letter-spacing: normal; text-align: start; =
text-indent: 0px; text-transform: none; white-space: normal; =
word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: =
none;">=E2=80=94</div><div style=3D"caret-color: rgb(0, 0, 0); color: =
rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: =
normal; font-variant-caps: normal; font-weight: normal; letter-spacing: =
normal; text-align: start; text-indent: 0px; text-transform: none; =
white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
text-decoration: none;"><br class=3D""></div><div style=3D"caret-color: =
rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Helvetica; font-size: =
12px; font-style: normal; font-variant-caps: normal; font-weight: =
normal; letter-spacing: normal; text-align: start; text-indent: 0px; =
text-transform: none; white-space: normal; word-spacing: 0px; =
-webkit-text-stroke-width: 0px; text-decoration: none;">Twitter / =
micro.blog: @ronaldoussoren</div><div style=3D"caret-color: rgb(0, 0, =
0); color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; =
font-style: normal; font-variant-caps: normal; font-weight: normal; =
letter-spacing: normal; text-align: start; text-indent: 0px; =
text-transform: none; white-space: normal; word-spacing: 0px; =
-webkit-text-stroke-width: 0px; text-decoration: none;">Blog: <a =
href=3D"https://blog.ronaldoussoren.net/" =
class=3D"">https://blog.ronaldoussoren.net/</a></div></div>
</div>
<div><br class=3D""><blockquote type=3D"cite" class=3D""><div =
class=3D"">On 24 May 2020, at 12:09, <a href=3D"mailto:[email protected]" =
class=3D"">[email protected]</a> wrote:</div><br =
class=3D"Apple-interchange-newline"><div class=3D""><div =
class=3D"">hello,<br class=3D""><br class=3D"">I use pyobjc bindings to =
build an application that is distributed [0].<br class=3D"">Unfortunately,=
 I have to rely on the Apple provided versions of python/pyobjc =
(2.7.16/2.5.1 on catalina).<br class=3D"">On Catalina, importing the =
AVFoundation framework leads to a runtime warning (Error parsing =
BridgeSupport data for AVFoundation), see below:<br class=3D""><br =
class=3D""> &nbsp;&nbsp;&nbsp;%python &nbsp;&nbsp;<br class=3D""> =
&nbsp;&nbsp;&nbsp;Python 2.7.16 (default, Feb 29 2020, 01:55:37) <br =
class=3D""> &nbsp;&nbsp;&nbsp;[GCC 4.2.1 Compatible Apple LLVM 11.0.3 =
(clang-1103.0.29.20) (-macos10.15-objc- on darwin<br class=3D""> =
&nbsp;&nbsp;&nbsp;Type "help", "copyright", "credits" or "license" for =
more information.<br class=3D""><blockquote type=3D"cite" =
class=3D""><blockquote type=3D"cite" class=3D""><blockquote type=3D"cite" =
class=3D"">import objc<br class=3D"">objc.__version__<br =
class=3D""></blockquote></blockquote></blockquote> =
&nbsp;&nbsp;&nbsp;'2.5.1'<br class=3D""><blockquote type=3D"cite" =
class=3D""><blockquote type=3D"cite" class=3D""><blockquote type=3D"cite" =
class=3D"">import AVFoundation<br =
class=3D""></blockquote></blockquote></blockquote> =
&nbsp;&nbsp;&nbsp;/System/Library/Frameworks/Python.framework/Versions/2.7=
/Extras/lib/python/PyObjC/objc/_bridgesupport.py:674: RuntimeWarning: =
Error parsing BridgeSupport data for AVFoundation: =
PyObjCRT_SkipTypeSpec: Unhandled type '5d' ]}<br class=3D""> =
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;warnings.warn("Error parsing BridgeSupport =
data for %s: %s" % (frameworkName, e), RuntimeWarning)<br class=3D""><br =
class=3D"">As a consequence, many things are not loaded properly.<br =
class=3D"">For example constants are missing (I can fix that by =
declaring the constants in my code).<br class=3D"">But I have a problem =
that I could not manage to fix myself:<br class=3D"">Methods that take a =
callback as parameter, like =
AVCaptureDevice.requestAccessForMediaType_completionHandler_, fail with =
a type error (Argument 3 is a block, but no signature available):<br =
class=3D""><br class=3D""><blockquote type=3D"cite" class=3D""><blockquote=
 type=3D"cite" class=3D""><blockquote type=3D"cite" =
class=3D"">AVMediaTypeVideo =3D "vide"<br class=3D"">from Foundation =
import NSObject<br class=3D"">class Test(NSObject):<br =
class=3D""></blockquote></blockquote></blockquote> &nbsp;&nbsp;&nbsp;... =
&nbsp;&nbsp;def test_(self, granted):<br class=3D""> =
&nbsp;&nbsp;&nbsp;... &nbsp;&nbsp;&nbsp;&nbsp;print(granted)<br =
class=3D""> &nbsp;&nbsp;&nbsp;... <br class=3D""><blockquote type=3D"cite"=
 class=3D""><blockquote type=3D"cite" class=3D""><blockquote type=3D"cite"=
 class=3D"">test =3D Test.alloc().init()<br =
class=3D"">AVFoundation.AVCaptureDevice.requestAccessForMediaType_completi=
onHandler_(<br class=3D""></blockquote></blockquote></blockquote> =
&nbsp;&nbsp;&nbsp;... &nbsp;&nbsp;AVMediaTypeVideo,<br class=3D""> =
&nbsp;&nbsp;&nbsp;... &nbsp;&nbsp;test.test_)<br class=3D""> =
&nbsp;&nbsp;&nbsp;Traceback (most recent call last):<br class=3D""> =
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;File "&lt;stdin&gt;", line 3, in =
&lt;module&gt;<br class=3D""> &nbsp;&nbsp;&nbsp;TypeError: Argument 3 is =
a block, but no signature available<br class=3D""><br =
class=3D""><blockquote type=3D"cite" class=3D""><blockquote type=3D"cite" =
class=3D""><blockquote type=3D"cite" class=3D"">test.test_.signature<br =
class=3D""></blockquote></blockquote></blockquote> =
&nbsp;&nbsp;&nbsp;'v@:@'<br class=3D""><blockquote type=3D"cite" =
class=3D""><blockquote type=3D"cite" class=3D""><blockquote type=3D"cite" =
class=3D"">AVFoundation.AVCaptureDevice.requestAccessForMediaType_completi=
onHandler_.signature<br class=3D""></blockquote></blockquote></blockquote>=
 &nbsp;&nbsp;&nbsp;'v32@0:8@16@?24'<br class=3D""><br class=3D"">Any =
idea on how to fix this problem without altering the default =
python/pyobjc installation?<br class=3D"">Thanks a lot for any =
suggestion,<br class=3D""><br class=3D"">Renaud<br class=3D""><br =
class=3D"">0. Pr=C3=A9sentation.app<br class=3D""><a =
href=3D"http://iihm.imag.fr/blanch/software/osx-presentation/" =
class=3D"">http://iihm.imag.fr/blanch/software/osx-presentation/</a><br =
class=3D""><br =
class=3D"">_______________________________________________<br =
class=3D"">Pyobjc-dev mailing list<br =
class=3D"">[email protected]<br =
class=3D"">https://lists.sourceforge.net/lists/listinfo/pyobjc-dev<br =
class=3D""></div></div></blockquote></div><br =
class=3D""></div></div></div></body></html>=

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