Thanks to Sze-Howe for pointing me out that I should post this to the
global thread, instead of to just the people who I talked to before.
Sorry to the two people who have now received this message twice!
sincerely,
Folling
Forwarded Message
Subject: Re: [Interest] Signal/Slot connection fails, even though
QMetaObject::activate is called
Date: Sat, 8 Feb 2020 01:21:04 +0100
From: Jonathan Purol
To: Tony Rietwyk
CC: Scott Bloom
I am so sincerely sorry everyone.
After manually removing every line of code to see when a MVCE would
work, I found a loose `blockSignals(true)` flying around that was there
from a debugging session.
I just want to curl up and cry, either in laughter or in sadness - but
three hours later and it finally works - sorry for wasting your time.
sincerely,
Folling
On 2/8/20 1:10 AM, Tony Rietwyk wrote:
Hi,
Does it work if you don't pass 'this' as the third argument to
connect? I never use that particular overload of connect. I usually
pass the lambda as the third argument.
Hope that helps, Tony
On 8/02/2020 10:03 am, Scott Bloom wrote:
Are you sure the function is getting called (via a break point)?
-Original Message-
From: Interest [mailto:interest-boun...@qt-project.org] On Behalf Of
Jonathan Purol
Sent: Friday, February 7, 2020 2:44 PM
To: Qt Project
Subject: [Interest] Signal/Slot connection fails, even though
QMetaObject::activate is called
Hello everyone,
I have a QMainWindow subclass called `text_editor` with a function
`save` which looks as follows:
```cpp
void text_editor::save() {
_textbox->document()->setModified(false);
_textbox->setFocus();
emit saved();
}
```
I now connect to that slot in another class like this:
```cpp
_information_editor = new text_editor{this};
connect(
_information_editor,
_editor::saved,
this,
[=]() {
std::cout << "hello\n";
}
);
```
I have verified that the signal is emitted, in fact, the method
generated by the moc:
```cpp
// SIGNAL 0
void text_editor::saved()
{
QMetaObject::activate(this, , 0, nullptr); }
``` is definitely called (verified with gdb and some other debugging
shenenigans).
In addition, the connection object returned by `connect` is valid, as
verified by its implicit bool-cast operator.
However, "hello" is never printed. I suspected this could be because
`text_editor` inherits from `QMainWindow` and could have a different
thread affinity, so I tried the following things:
1. Move the editor to the same thread as the object which establishes
the connection 2. Use a QueuedConnection 3. Connect to the slot from
WITHIN the text editor itself, making sure that we are 100% on the
same slot
and none of them worked.
Just for clarification, the print of "hello" is only an example, so
even if there was some issue with that, I would have detected it, the
actual code is of course different.
I'm really out of luck here, and would appreciate any help.
Sincerely,
Folling
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