Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. slot will be called multi-times if connect() multi-times, is there any way to check this error?
Qt 6.11 is out! See what's new in the release blog

slot will be called multi-times if connect() multi-times, is there any way to check this error?

Scheduled Pinned Locked Moved Unsolved General and Desktop
13 Posts 4 Posters 2.2k Views 1 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • SeeLookS Offline
    SeeLookS Offline
    SeeLook
    wrote on last edited by
    #4
    This post is deleted!
    1 Reply Last reply
    0
    • SeeLookS Offline
      SeeLookS Offline
      SeeLook
      wrote on last edited by
      #5

      @opengpu2 Do You have some reason for that?
      Here is doc of connection types:
      http://doc.qt.io/qt-5.5/qt.html#ConnectionType-enum

      O 1 Reply Last reply
      0
      • O opengpu2

        @SeeLook what should i do if i set the last argument Qt::QueuedConnection...

        J Offline
        J Offline
        Jakob
        wrote on last edited by
        #6

        @opengpu2 You can combine options: simply use Qt::QueuedConnection | Qt::UniqueConnection as last argument to the connect call

        O 2 Replies Last reply
        0
        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #7

          Hi,

          Connect doesn't overwrite anything, it just creates a new connection unless you use Qt:UniqueConnection like our fellows suggested.

          However that's an option that's rarely used, what is your use case ?

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

          O 1 Reply Last reply
          0
          • SeeLookS SeeLook

            @opengpu2 Do You have some reason for that?
            Here is doc of connection types:
            http://doc.qt.io/qt-5.5/qt.html#ConnectionType-enum

            O Offline
            O Offline
            opengpu2
            wrote on last edited by
            #8

            @SeeLook yep, cross thread use QueuedConnection

            1 Reply Last reply
            0
            • J Jakob

              @opengpu2 You can combine options: simply use Qt::QueuedConnection | Qt::UniqueConnection as last argument to the connect call

              O Offline
              O Offline
              opengpu2
              wrote on last edited by
              #9

              @Jakob so if i set Qt::UniqueConnection, that is equal to Qt::QueuedConnection | Qt::UniqueConnection. right?

              1 Reply Last reply
              0
              • SGaistS SGaist

                Hi,

                Connect doesn't overwrite anything, it just creates a new connection unless you use Qt:UniqueConnection like our fellows suggested.

                However that's an option that's rarely used, what is your use case ?

                O Offline
                O Offline
                opengpu2
                wrote on last edited by
                #10

                @SGaist i wonder why Qt allow the same connect to be created multi-times... i wrongly wrote some connect in func except Constructor&Init(). and when that func is called multi-times, then each emit will cause multi-time slot...
                i think Qt:UniqueConnection is set by default will be more safe.
                can i write a custom macro to replace all connect and let them use Qt:UniqueConnection

                1 Reply Last reply
                0
                • J Jakob

                  @opengpu2 You can combine options: simply use Qt::QueuedConnection | Qt::UniqueConnection as last argument to the connect call

                  O Offline
                  O Offline
                  opengpu2
                  wrote on last edited by
                  #11

                  @Jakob i directly set the last param as Qt::QueuedConnection | Qt::UniqueConnection, but there is error canno convert from 'int' to 'Qt::ConnectionType'.
                  so i have to write like this? (Qt::ConnectionType)(Qt::QueuedConnection | Qt::UniqueConnection)

                  1 Reply Last reply
                  0
                  • SGaistS Offline
                    SGaistS Offline
                    SGaist
                    Lifetime Qt Champion
                    wrote on last edited by
                    #12

                    While there are valid use cases, most of the time creating the exact same connection several times is a design/coding error so making UniqueConnection the default would just hide it and thus open the path to hard to debug behavior/bugs.

                    Interested in AI ? www.idiap.ch
                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                    O 1 Reply Last reply
                    0
                    • SGaistS SGaist

                      While there are valid use cases, most of the time creating the exact same connection several times is a design/coding error so making UniqueConnection the default would just hide it and thus open the path to hard to debug behavior/bugs.

                      O Offline
                      O Offline
                      opengpu2
                      wrote on last edited by
                      #13

                      @SGaist ok thank you

                      1 Reply Last reply
                      0

                      • Login

                      • Login or register to search.
                      • First post
                        Last post
                      0
                      • Categories
                      • Recent
                      • Tags
                      • Popular
                      • Users
                      • Groups
                      • Search
                      • Get Qt Extensions
                      • Unsolved