Re: multiple changed events?

Thanks for the quick response, Emmanuele.

Emmanuele Bassi wrote:
On Tue, 2007-09-25 at 11:32 +0100, Dave Howorth wrote:

The changed callback is called twice from within set_text. The first
time, the text is an empty string. The second time it is the value that
was passed to set_text.

the convention in gtk+ is that any changed signal is emitted at least
once when "something" changes: there's no upper bound, just the lower

Hmm, I click on a button to make a bank transfer and the transfer
happens twice? I saw this issue once in an inter-bank transfer system.
The recipient said both transfers were correctly authorised and refused
to give the money (a million or two) back :(

having said this, you can block the emission of a particular signal, or
the calling of a specific callback. for instance:

  $entry->signal_handlers_block_by_func(\&your_entry_callback, $data);
  $entry->signal_handlers_unblock_by_func(\&your_entry_callback, $data);

will result in your callback not being invoked[2]; you can use this
inside the callback of the other widget that controls the contents of
the entry.

AFAICT, this would mean that my callback is not called at all. I need it
to be called once, so I've added my own semaphore around the call to
set_text and a check for the text widget's content being non-empty.
Fortunately I know that this text value can never be empty. But if the
text value could be empty I guess I'd have to set the semaphore before
calling set_text and clear it within the callback. And then I'd be
committed to a specific [buggy, IMHO] implementation of set_text.

[1] I think there's a bug open, somewhere in bugzilla, for this specific
instance (making a set_text() atomic); personally, I think it's merely a
matter of taste: the ::changed signal convention is known and

It's not documented where it's needed! (i.e. at
I don't understand how it can be viewed as a matter of taste? But I have
a workaround :)

Thanks again for the reply - at least I know it's not something I've
done wrong.

Thanks, Dave

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