Automatic connection of QML signal and C++ slot?
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@Tom-asso
Yes in the sense that every binding is an automatic signal/slot connection.
No in the sense, that functional slots have to be explicitly connected. The syntax is quite simple, so I wouldn’t even call that a downside.@Axel-Spoerl Design question for you:
If my C++ app must respond to multiple menu actions, e.g. 10 actions, then my C++ code must do the following, right?- declare/define 10 slot functions
- make 10 calls to connect(), once for each slot declared in step 1
That's the gist of it, right? Those 10 connect() calls just seem like a lot of application code to a lazy sob like me. ;-) Or is there an easier way to do it?
Do qtcreator or qtdesignstudio offer a more 'automatic' way?
Thanks! -
@Axel-Spoerl Design question for you:
If my C++ app must respond to multiple menu actions, e.g. 10 actions, then my C++ code must do the following, right?- declare/define 10 slot functions
- make 10 calls to connect(), once for each slot declared in step 1
That's the gist of it, right? Those 10 connect() calls just seem like a lot of application code to a lazy sob like me. ;-) Or is there an easier way to do it?
Do qtcreator or qtdesignstudio offer a more 'automatic' way?
Thanks! -
@Axel-Spoerl Design question for you:
If my C++ app must respond to multiple menu actions, e.g. 10 actions, then my C++ code must do the following, right?- declare/define 10 slot functions
- make 10 calls to connect(), once for each slot declared in step 1
That's the gist of it, right? Those 10 connect() calls just seem like a lot of application code to a lazy sob like me. ;-) Or is there an easier way to do it?
Do qtcreator or qtdesignstudio offer a more 'automatic' way?
Thanks!@Tom-asso said in Automatic connection of QML signal and C++ slot?:
If my C++ app must respond to multiple menu actions, e.g. 10 actions, then my C++ code must do the following, right?
- declare/define 10 slot functions
- make 10 calls to connect(), once for each slot declared in step 1
That's the gist of it, right?
Yes.
Those 10 connect() calls just seem like a lot
yy9pis the sequence in vim, doing 80% of this job for you. The rest is usually about editing a few letters :-)You can of course use autoconnect - totally fine, it has been designed for the comfort you are seeking.
The caveat is, that a mismatch of a single character will leave signal/slot unconnected without notice.
Depending on an exact string match in an XML file and C++ code, comes particularly unhandy when searching for a bug. I have seen furious forum posts and bugreports aboutQObject::connect()allegedly not working properly. I remember a project from a few years ago, where a company's quality department has done a huge effort inrenaming_all_underline_stuff intoCamelStyle, autoconnected slots included. Compiled like a charm, and set the UI on fire. -
Automatic connection of QtWidgets and C++ application code saves lots of development time. Is there a similar automatic connection feature for QML/QtQuick signals and application code, or do I have write my own calls to QObject::connect() for every QML Item that my C++ application code is concerned with? If automatic connection is not supported for this, why not?
Thanks!@Tom-asso don't use that feature if you can help yourself!
These days there's Ai/copilot to do repetitive boring and simple tasks. Like creating slots for signals or unit tests for functions.
Rather use that.
Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct
Q: What's that?
A: It's blue light.
Q: What does it do?
A: It turns blue. -
@Tom-asso don't use that feature if you can help yourself!
These days there's Ai/copilot to do repetitive boring and simple tasks. Like creating slots for signals or unit tests for functions.
Rather use that.
@J-Hilk said in Automatic connection of QML signal and C++ slot?:
These days there's Ai/copilot to do repetitive boring and simple tasks.
Nothing will ever equate to the efficiency and clarity of @Axel-Spoerl's
yy9pin vim ;-) -
@J-Hilk said in Automatic connection of QML signal and C++ slot?:
These days there's Ai/copilot to do repetitive boring and simple tasks.
Nothing will ever equate to the efficiency and clarity of @Axel-Spoerl's
yy9pin vim ;-)@JonB I actually have no idea what it is :P first time I heard about it.
But just wait until Ai is part of your OS and always listening, like Alexa....
Not a disturbing thought at all.
Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct
Q: What's that?
A: It's blue light.
Q: What does it do?
A: It turns blue. -
@JonB I actually have no idea what it is :P first time I heard about it.
But just wait until Ai is part of your OS and always listening, like Alexa....
Not a disturbing thought at all.
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@J-Hilk If you don't know what
yy9pdoes in vi your life is lacking. Surely it's clear what it does anyway... ;) -
@J-Hilk If you don't know what
yy9pdoes in vi your life is lacking. Surely it's clear what it does anyway... ;)I'm sorry but do not connect to QML signals in c++, even though it's simple with some editor magic (Qt Creator ctrl-d is much easier to grok than vim bindings btw). You will still be left with verbose and subpar code.
https://doc.qt.io/qt-5/qtquick-bestpractices.html#interacting-with-qml-from-c
https://doc.qt.io/qt-6/qtquick-bestpractices.html#exposing-data-from-c-to-qml
https://doc.qt.io/qt-6/qtqml-cppintegration-overview.html#interacting-with-qml-objects-from-c
https://youtu.be/vzs5VPTf4QQ?t=23m20s -
@Tom-asso said in Automatic connection of QML signal and C++ slot?:
If my C++ app must respond to multiple menu actions, e.g. 10 actions, then my C++ code must do the following, right?
- declare/define 10 slot functions
- make 10 calls to connect(), once for each slot declared in step 1
That's the gist of it, right?
Yes.
Those 10 connect() calls just seem like a lot
yy9pis the sequence in vim, doing 80% of this job for you. The rest is usually about editing a few letters :-)You can of course use autoconnect - totally fine, it has been designed for the comfort you are seeking.
The caveat is, that a mismatch of a single character will leave signal/slot unconnected without notice.
Depending on an exact string match in an XML file and C++ code, comes particularly unhandy when searching for a bug. I have seen furious forum posts and bugreports aboutQObject::connect()allegedly not working properly. I remember a project from a few years ago, where a company's quality department has done a huge effort inrenaming_all_underline_stuff intoCamelStyle, autoconnected slots included. Compiled like a charm, and set the UI on fire.@Axel-Spoerl autoconnect is only for Qt-Widgets, not enabled for QtQuick/QML, correct?
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I'm sorry but do not connect to QML signals in c++, even though it's simple with some editor magic (Qt Creator ctrl-d is much easier to grok than vim bindings btw). You will still be left with verbose and subpar code.
https://doc.qt.io/qt-5/qtquick-bestpractices.html#interacting-with-qml-from-c
https://doc.qt.io/qt-6/qtquick-bestpractices.html#exposing-data-from-c-to-qml
https://doc.qt.io/qt-6/qtqml-cppintegration-overview.html#interacting-with-qml-objects-from-c
https://youtu.be/vzs5VPTf4QQ?t=23m20s@GrecKo - Thanks for those references! I think I generally agree with you now (after I wrote my entire freaking C++ app using signals/slots!). But are there cases where QML signal to C++ slot makes sense? Maybe in the case of one QML emitter and multiple C++ 'listeners'?
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@GrecKo - Thanks for those references! I think I generally agree with you now (after I wrote my entire freaking C++ app using signals/slots!). But are there cases where QML signal to C++ slot makes sense? Maybe in the case of one QML emitter and multiple C++ 'listeners'?
@Tom-asso said in Automatic connection of QML signal and C++ slot?:
But are there cases where QML signal to C++ slot makes sense? Maybe in the case of one QML emitter and multiple C++ 'listeners'?
It’s better to call a C++ function from QML and do the plumbing in C++, I wouldn’t know of a use case where such connections are the best possible solution.
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@JonB so I asked chatgpt :P so I now know!
and I also generally try not to use a cmd line text editor if I can help it ;)
@J-Hilk said in Automatic connection of QML signal and C++ slot?:
I also generally try not to use a cmd line text editor if I can help it ;)
There also graphical versions of vi. And Qt Creator supports FakeVim which you can quickly toggle.
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@J-Hilk said in Automatic connection of QML signal and C++ slot?:
I also generally try not to use a cmd line text editor if I can help it ;)
There also graphical versions of vi. And Qt Creator supports FakeVim which you can quickly toggle.
@SimonSchroeder I think @J-Hilk's interest in using vi/vim in any shape or form is absolute 0! We were jesting back & forth.
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T Tom asso has marked this topic as solved on
