Does C++17 -> "std::any" conflict with QT's control class?

X-Crack

Std::any var = std::make_any<QPushButton>("123123", Q_NULLPTR);
As the example above, no matter how I write, the compiler will report an error as follows:

1>c:\program files (x86)\microsoft visual studio\2017\enterprise\vc\tools\msvc\14.16.27023\include\any(471): error C2440: "Initialization": Unable to convert from "initializer list" Is "std::any"
1>c:\program files (x86)\microsoft visual studio\2017\enterprise\vc\tools\msvc\14.16.27023\include\any(470): note: no constructor can accept source types, or constructor weights Uncertain decision
Note: See the reference to the function template being compiled. "std::any std::make_any<QPushButton, const char(&)[7], nullptr>(const char (&)[7], nullptr &&)"

May I ask how to solve it, thank you very much for your international friends.

aha_1980

Hi @X-Crack, welcome

which compiler is this? is it C++17 capable?
do you have CONFIG+=C++1z in your .pro file?

Regards

X-Crack

@aha_1980
My development environment:Visual Studio 2017 15.9.3
fully supported C++17 is used.
Sorry, forgive me for being a newcomer, only 600 seconds to post a topic.

SGaist

Hi,

Based on this Visual C++ Team Blog post, std::any requires a copyable type which QObject based classes are not.

Furthermore, QPushButton doesn't have a constructor which takes an initialiser list.

J.Hilk

@X-Crack well, the template is template< class T, class... Args >

therefore shouldn't that be

Std::any var = std::make_any<QPushButton, QString, QObject>("123123", Q_NULLPTR);

?

X-Crack

@SGaist
I understand, thank you very much.
But I am now experiencing a new situation.
Cause: After using the smart pointer in the standard library, the program crashed when it exited. I think it might have been "delete" twice.

Std::unordered_map<std::string, std::shared_ptr<QObject>>

This is what I wrote. I want to add more control classes to the map and then manage it.
The reality is cruel, and the problems come one after another.
I am very upset now.

JKSH

@X-Crack said in Does C++17 -> "std::any" conflict with QT's control class?:

Cause: After using the smart pointer in the standard library, the program crashed when it exited. I think it might have been "delete" twice.

... std::shared_ptr<QObject>

This is what I wrote. I want to add more control classes to the map and then manage it.

QObject already does some automatic memory management: https://doc.qt.io/qt-5/objecttrees.html

It is dangerous to use std::shared_ptr with QObject because double deletions can happen very easily. It is safer to store raw pointers (QObject*) in your map -- remember to delete the top-level object when you have finished.

The reality is cruel, and the problems come one after another.
I am very upset now.

加油!

X-Crack

@JKSH

thank you very much.
Sincerely thank the foreign friends.
Although I can only rely on "GOOGLE" translation to communicate with you.
But some words are not standard and you can understand.
I have basically understood the memory and pointer characteristics in QT.

JKSH

@X-Crack You're welcome. If we say something that you don't understand, just ask us to explain more.

X-Crack

@JKSH

I understand, thank you.
I changed the way I realized the previous idea.
Just redesigned