Re: SpinButton: how to avoid calling signal handler when set_value()

2016-11-02 Thread Michael Torrie 
On 11/02/2016 05:19 PM, pozzugno wrote:
> It seems pyGObject implementation gives only two "handler block" 
> functions: handler_block(), that needs the handler_id that I don't have; 
> handler_block_by_func() that needs the callback to block (the same 
> problem of your solution, because I have different callbacks).

Usually when you connect a signal, the return value from the connect
call is the handler_id.  Can you save this value somewhere for future use?

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Re: SpinButton: how to avoid calling signal handler when set_value()

2016-11-02 Thread pozzugno 

Il 02/11/2016 18:55, Nicola Fontana ha scritto:

Il Wed, 2 Nov 2016 14:40:58 +0100 Pozz Pozz  scrisse:


2016-11-02 11:24 GMT+01:00 Nicola Fontana :

...

you don't necessarily need the handler id. In C (I don't use
python) you could write the following:

void my_set_value(GtkSpinButton *spin_button, gdouble value)
{
 g_signal_handlers_block_matched(spin_button,
 G_SIGNAL_MATCH_FUNC,
 0, 0, NULL,
 callback_to_skip,
 NULL);

 /* This will not trigger callback_to_skip */
 gtk_spin_button_set_value(spin_button, value)

 g_signal_handlers_unblock_matched(spin_button,
   G_SIGNAL_MATCH_FUNC,
   0, 0, NULL,
   callback_to_skip,
   NULL);
}
  

I got the idea. I don't know if g_signal_handlers_block_matched() or
similar functionality is available in Python. However, remaining in C, your
code make the assumption there is a single callback function for all the
spinbuttons. This is not true: I have a different handler for each
spinbutton, because I have to make different things.

Sorry but I am a developer, not a mind reader.

Yes, of course :-) Thank you for spending some time for me.

I thought using a different callback for each SpinButton was the more 
typical solution.



You can match by data or try to lookup the callback by detail with
g_signal_handler_find or refactor your code to use a single
callback.
It seems pyGObject implementation gives only two "handler block" 
functions: handler_block(), that needs the handler_id that I don't have; 
handler_block_by_func() that needs the callback to block (the same 
problem of your solution, because I have different callbacks).


Is it possible to retrieve the list of connected callbacks of an object 
and a signal name ("value-changed")?



The fact that you are using different callbacks has a
foul smell indeed.
Yes? I have to generate and send a different request to the device. Why 
do you think it's better to have a single callback?

Of course, I could write one single callback as:

  def callback(self, spinbutton):
if spinbutton is spinSetting1:
  self.callback_setting1(spinbutton)
elif spinbutton is spinSetting2:
  self.callback_setting2(spinbutton)
...

  def callback_setting1(self,spinbutton):
# This is the callback of the spinbutton associated to setting1 
parameter

set_setting1(spinbutton.get_value())

It seems to me a more complicated way to write different callbacks.

IMHO the solution to use a refreshing flag is the simplest solution, 
even if a little dirty. Alternatively, I have to create a list of 
spinbuttons *and* callbacks and search for the callback to unblock in 
your suggested function my_set_value().



Come on, a little bit of initiative. Here, today only, the link to
the official (C) documentation:

https://developer.gnome.org/gobject/stable/gobject-Signals.html

Please, don't think I don't use to read documentation.


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Re: SpinButton: how to avoid calling signal handler when set_value()

2016-11-02 Thread Nicola Fontana 
Il Wed, 2 Nov 2016 14:40:58 +0100 Pozz Pozz  scrisse:

> 2016-11-02 11:24 GMT+01:00 Nicola Fontana :
> > ...
> >
> > you don't necessarily need the handler id. In C (I don't use
> > python) you could write the following:
> >
> > void my_set_value(GtkSpinButton *spin_button, gdouble value)
> > {
> > g_signal_handlers_block_matched(spin_button,
> > G_SIGNAL_MATCH_FUNC,
> > 0, 0, NULL,
> > callback_to_skip,
> > NULL);
> >
> > /* This will not trigger callback_to_skip */
> > gtk_spin_button_set_value(spin_button, value)
> >
> > g_signal_handlers_unblock_matched(spin_button,
> >   G_SIGNAL_MATCH_FUNC,
> >   0, 0, NULL,
> >   callback_to_skip,
> >   NULL);
> > }
> >  
> 
> I got the idea. I don't know if g_signal_handlers_block_matched() or
> similar functionality is available in Python. However, remaining in C, your
> code make the assumption there is a single callback function for all the
> spinbuttons. This is not true: I have a different handler for each
> spinbutton, because I have to make different things.

Sorry but I am a developer, not a mind reader.

You can match by data or try to lookup the callback by detail with
g_signal_handler_find or refactor your code to use a single
callback. The fact that you are using different callbacks has a
foul smell indeed.

Come on, a little bit of initiative. Here, today only, the link to
the official (C) documentation:

https://developer.gnome.org/gobject/stable/gobject-Signals.html

Ciao.
-- 
Nicola
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Re: SpinButton: how to avoid calling signal handler when set_value()

2016-11-02 Thread Nicola Fontana 
Il Wed, 2 Nov 2016 10:23:44 +0100 Pozz Pozz  scrisse:
> ...
> How do you implement the generic function _my_set_value()? It should have
> two parameters: spinbutton and value. signal_handler_block() function needs
> the handler_id associated that I don't have.
> Maybe during initialization, when I connected the handlers, I could create
> a data structure (a list) with spinbuttons and associated handler_id. In
> this way, _my_set_value() could accept the item of the list and could
> recover the handler_id to block.
> 
> However there is another problem with this approach. I'm using Glade and I
> connect *all* the handlers with a single instruction:
> builder.connect_signals(). So I don't have the handler IDs.
> ...

Hi,

you don't necessarily need the handler id. In C (I don't use
python) you could write the following:

void my_set_value(GtkSpinButton *spin_button, gdouble value)
{
g_signal_handlers_block_matched(spin_button,
G_SIGNAL_MATCH_FUNC,
0, 0, NULL,
callback_to_skip,
NULL);

/* This will not trigger callback_to_skip */
gtk_spin_button_set_value(spin_button, value)

g_signal_handlers_unblock_matched(spin_button,
  G_SIGNAL_MATCH_FUNC,
  0, 0, NULL,
  callback_to_skip,
  NULL);
}

Not tested, but should give you the idea.

Ciao.
-- 
Nicola
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Re: SpinButton: how to avoid calling signal handler when set_value()

2016-11-02 Thread Nicola Fontana 
Il Wed, 2 Nov 2016 00:09:29 +0100 pozzugno  scrisse:

> ...
> A simple and clear sequence of instructions:
> 
>_set_value()
>_set_value()
>..
> 
> will be transformed in a complex, long and cryptic sequence of 
> instructions:
> 
>_block()
>_set_value()
>_unblock()
>_block()
>_set_value()
>_unblock()

Hi,

I hope you are missing some fundamental detail because this is a
non-problem.

_my_set_value()
_block()
_set_value()
_unblock

_my_set_value()
_my_set_value()

> I hoped there was another better solution. Actually I'm using a flag 
> that is checked in the handler:
> 
>refreshing = True
>_set_value()
>_set_value()
>...
>refreshing = False

This is not equivalent to what you wrote above. This is (roughly)
equivalent to:

_block()
_set_value()
_set_value()
...
_unblock()

A minimal test case exposing the problem would be much clearer.

Ciao.
-- 
Nicola
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