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bug in demo9?
Joined: 17 May 2006
Posts: 32
bug in demo9?
Hi:
read line 25 in module.pas in demo9:
Result := nil;
it takes a error: "SystemError: error return without exception set" when running
into this line. I fix it:
Result := Py_None;
now it work well.
I use Delphi7 + p4d 3.31. Is it a bug?
I have another question. After "Add" function in this unit, it must use "far"
and "cdecl".
Joined: 29 Apr 2005
Posts: 103
bug in demo9?
Hi,
>read line 25 in module.pas in demo9:
>Result := nil;
>it takes a error: "SystemError: error return without exception set" when
>running
>into this line. I fix it:
>Result := Py_None;
>now it work well.
>I use Delphi7 + p4d 3.31. Is it a bug?
No, the code is correct. I don`t know why in your case you get such an
exception as it works fine with my D7.
The Python function PyArg_ParseTuple will return an integer telling you if
it could parse or not the parameters.
If yes then you have to provide a valid Python object as a result (such as
Py_None which by the way must be incremented before returning it!!!!!!
That`s why you should write something like Result := ReturnNone; which will
do it for you).
If it could not parse the parameters, it will create its own error message
and in that case you MUST return nil.
>I have another question. After "Add" function in this unit, it must use
>"far"
>and "cdecl".
I think that "Far" is obsolete now.
But "cdecl" is a must as Python APIs are coded in the C language.
Bye,
Morgan
Joined: 17 May 2006
Posts: 32
bug in demo9?
I get it. thank your particular explain.
in fact, I write some demo for p4d which will be post in py4d wiki.
First of these is to create a new modal for python extention which
return None. After looking demo9, I think simply that return nil is
ok, but I`m wrong. Return value must be python type value in any case,
but nil is not a python type value.
--tocer
Morgan Martinet wrote::
> Hi,
>
>> read line 25 in module.pas in demo9:
>
>> Result := nil;
>
>> it takes a error: "SystemError: error return without exception set" when
>> running
>> into this line. I fix it:
>
>> Result := Py_None;
>
>> now it work well.
>
>> I use Delphi7 + p4d 3.31. Is it a bug?
>
> No, the code is correct. I don`t know why in your case you get such an
> exception as it works fine with my D7.
> The Python function PyArg_ParseTuple will return an integer telling you if
> it could parse or not the parameters.
> If yes then you have to provide a valid Python object as a result (such as
> Py_None which by the way must be incremented before returning it!!!!!!
> That`s why you should write something like Result := ReturnNone; which will
> do it for you).
> If it could not parse the parameters, it will create its own error message
> and in that case you MUST return nil.
>
>> I have another question. After "Add" function in this unit, it must use
>> "far"
>> and "cdecl".
> I think that "Far" is obsolete now.
> But "cdecl" is a must as Python APIs are coded in the C language.
>
> Bye,
>
> Morgan
Joined: 29 Apr 2005
Posts: 103
bug in demo9?
> in fact, I write some demo for p4d which will be post in py4d wiki.
> First of these is to create a new modal for python extention which
> return None. After looking demo9, I think simply that return nil is
> ok, but I`m wrong. Return value must be python type value in any
case,
> but nil is not a python type value.
I have to see your code before continuing this discussion as I don`t
understand what you`re trying to do!
Returning nil is perfectly Ok when PyErr_Occurred returns a non nil
value, which will be the case when PyArge_ParseTuple fails.
Of course, when no error has been set (with PyErr_SetString for
instance), then you CAN`T return nil!
Demo9 has been there for a lot of years and was never reported as
buggy.
Bye,
Morgan
Joined: 17 May 2006
Posts: 32
bug in demo9?
Hi Morgan:
I understand your typing. my case is very simple:
function hello: PPyObject; cdecl;
begin
with GetPythonEngine do begin
Writeln(`hello world`);
Result := Py_None;
end;
end;
no error has been set, I only want to expose delphi function to python:)
Now, I think we could stop the discuss :)
thank your paticular reply !
--tocer
Morgan Martinet wrote::
>> in fact, I write some demo for p4d which will be post in py4d wiki.
>> First of these is to create a new modal for python extention which
>> return None. After looking demo9, I think simply that return nil is
>> ok, but I`m wrong. Return value must be python type value in any case,
>> but nil is not a python type value.
>
> I have to see your code before continuing this discussion as I don`t
> understand what you`re trying to do!
> Returning nil is perfectly Ok when PyErr_Occurred returns a non nil
> value, which will be the case when PyArge_ParseTuple fails.
> Of course, when no error has been set (with PyErr_SetString for
> instance), then you CAN`T return nil!
> Demo9 has been there for a lot of years and was never reported as
> buggy.
>
> Bye,
>
> Morgan
Joined: 29 Apr 2005
Posts: 103
bug in demo9?
--- In pythonfordelphi@yahoogroups.com, tocer <tocer.deng@...> wrote:
>
> Hi Morgan:
>
> I understand your typing. my case is very simple:
>
> function hello: PPyObject; cdecl;
> begin
> with GetPythonEngine do begin
> Writeln(`hello world`);
> Result := Py_None;
> end;
> end;
>
> no error has been set, I only want to expose delphi function to
python:)
>
> Now, I think we could stop the discuss :)
>
> thank your paticular reply !
Ok, this is simple, but wrong! As I already said, you make always
take reference counting into account when dealing with Python
object, and thus you must inc ref Py_Result or it will crash Python
if you invoke your method several times.
So, this should be:
function hello: PPyObject; cdecl;
begin
with GetPythonEngine do begin
Writeln(`hello world`);
Result := ReturnNone;
{ or Result := Py_None;
Py_IncRef(Result); }
end;
end;
Bye,
Morgan
Joined: 17 May 2006
Posts: 32
bug in demo9?
oops,it is not simple :( I have to study hard.
but thanks.
--tocer
Morgan Martinet wrote::
> --- In pythonfordelphi@yahoogroups.com, tocer <tocer.deng@...> wrote:
>> Hi Morgan:
>>
>> I understand your typing. my case is very simple:
>>
>> function hello: PPyObject; cdecl;
>> begin
>> with GetPythonEngine do begin
>> Writeln(`hello world`);
>> Result := Py_None;
>> end;
>> end;
>>
>> no error has been set, I only want to expose delphi function to
> python:)
>> Now, I think we could stop the discuss :)
>>
>> thank your paticular reply !
> Ok, this is simple, but wrong! As I already said, you make always
> take reference counting into account when dealing with Python
> object, and thus you must inc ref Py_Result or it will crash Python
> if you invoke your method several times.
>
> So, this should be:
>
> function hello: PPyObject; cdecl;
> begin
> with GetPythonEngine do begin
> Writeln(`hello world`);
> Result := ReturnNone;
> { or Result := Py_None;
> Py_IncRef(Result); }
> end;
> end;
>
> Bye,
>
> Morgan
>
>
>
>
>
>
>
> To Post a message, send it to: pythonfordelphi@eGroups.com
>
> To Unsubscribe, send a blank message to:
pythonfordelphi-unsubscribe@eGroups.com
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
Joined: 29 Apr 2005
Posts: 103
bug in demo9?
In fact, you can read Python material first as any Python rules applies to
P4D too!
In the Python documentation, there is a section on embedding Python into an
application...
> -----Original Message-----
> From: pythonfordelphi@yahoogroups.com
> [mailto:pythonfordelphi@yahoogroups.com] On Behalf Of tocer
> Sent: Monday, May 22, 2006 11:19 AM
> To: pythonfordelphi@yahoogroups.com
> Subject: Re: [pythonfordelphi] Re: bug in demo9?
>
> oops,it is not simple :( I have to study hard.
>
> but thanks.
>
> --tocer
>
> Morgan Martinet wrote::
> > --- In pythonfordelphi@yahoogroups.com, tocer <tocer.deng@...> wrote:
> >> Hi Morgan:
> >>
> >> I understand your typing. my case is very simple:
> >>
> >> function hello: PPyObject; cdecl;
> >> begin
> >> with GetPythonEngine do begin
> >> Writeln(`hello world`);
> >> Result := Py_None;
> >> end;
> >> end;
> >>
> >> no error has been set, I only want to expose delphi function to
> > python:)
> >> Now, I think we could stop the discuss :)
> >>
> >> thank your paticular reply !
> > Ok, this is simple, but wrong! As I already said, you make always
> > take reference counting into account when dealing with Python
> > object, and thus you must inc ref Py_Result or it will crash Python
> > if you invoke your method several times.
> >
> > So, this should be:
> >
> > function hello: PPyObject; cdecl;
> > begin
> > with GetPythonEngine do begin
> > Writeln(`hello world`);
> > Result := ReturnNone;
> > { or Result := Py_None;
> > Py_IncRef(Result); }
> > end;
> > end;
> >
> > Bye,
> >
> > Morgan
> >
> >
> >
> >
> >
> >
> >
> > To Post a message, send it to: pythonfordelphi@eGroups.com
> >
> > To Unsubscribe, send a blank message to: pythonfordelphi-
> unsubscribe@eGroups.com
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>
>
> To Post a message, send it to: pythonfordelphi@eGroups.com
>
> To Unsubscribe, send a blank message to: pythonfordelphi-
> unsubscribe@eGroups.com
> Yahoo! Groups Links
>
>
>
>
Joined: 17 May 2006
Posts: 32
bug in demo9?
ok,I`ll try it.
thanks
--tocer
Morgan Martinet wrote::
> In fact, you can read Python material first as any Python rules applies to
> P4D too!
> In the Python documentation, there is a section on embedding Python into an
> application...
>
>> -----Original Message-----
>> From: pythonfordelphi@yahoogroups.com
>> [mailto:pythonfordelphi@yahoogroups.com] On Behalf Of tocer
>> Sent: Monday, May 22, 2006 11:19 AM
>> To: pythonfordelphi@yahoogroups.com
>> Subject: Re: [pythonfordelphi] Re: bug in demo9?
>>
>> oops,it is not simple :( I have to study hard.
>>
>> but thanks.
>>
>> --tocer
>>
>> Morgan Martinet wrote::
>>> --- In pythonfordelphi@yahoogroups.com, tocer <tocer.deng@...> wrote:
>>>> Hi Morgan:
>>>>
>>>> I understand your typing. my case is very simple:
>>>>
>>>> function hello: PPyObject; cdecl;
>>>> begin
>>>> with GetPythonEngine do begin
>>>> Writeln(`hello world`);
>>>> Result := Py_None;
>>>> end;
>>>> end;
>>>>
>>>> no error has been set, I only want to expose delphi function to
>>> python:)
>>>> Now, I think we could stop the discuss :)
>>>>
>>>> thank your paticular reply !
>>> Ok, this is simple, but wrong! As I already said, you make always
>>> take reference counting into account when dealing with Python
>>> object, and thus you must inc ref Py_Result or it will crash Python
>>> if you invoke your method several times.
>>>
>>> So, this should be:
>>>
>>> function hello: PPyObject; cdecl;
>>> begin
>>> with GetPythonEngine do begin
>>> Writeln(`hello world`);
>>> Result := ReturnNone;
>>> { or Result := Py_None;
>>> Py_IncRef(Result); }
>>> end;
>>> end;
>>>
>>> Bye,
>>>
>>> Morgan
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> To Post a message, send it to: pythonfordelphi@eGroups.com
>>>
>>> To Unsubscribe, send a blank message to: pythonfordelphi-
>> unsubscribe@eGroups.com
>>> Yahoo! Groups Links
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>> To Post a message, send it to: pythonfordelphi@eGroups.com
>>
>> To Unsubscribe, send a blank message to: pythonfordelphi-
>> unsubscribe@eGroups.com
>> Yahoo! Groups Links
>>
>>
>>
>>
>
>
>
>
>
> To Post a message, send it to: pythonfordelphi@eGroups.com
>
> To Unsubscribe, send a blank message to:
pythonfordelphi-unsubscribe@eGroups.com
> Yahoo! Groups Links
>
>
>
>
>
>
>
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