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Thread: [SOLVED] connect overloaded signal with parameter

  1. #1
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    Default [SOLVED] connect overloaded signal with parameter

    Hi

    I prefer to use the more modern signal/slot connect() version as it is typesafe at run-time. Copied from the Qt documentation: "QObject::connect(lineEdit, &QLineEdit::textChanged, label, &QLabel::setText);". How is this done when there are overloaded functions and/or signals?

    Examples:
    • "connect(camera, &QCamera::error, this, &CaptureDialog::errorSlot);" does not compile because there are two QCamera::error functions: the signal "QCamera::error(QCamera::Error)" and the regular function "QCamera::error() const"
    • "connect(camera, &QCamera::lockStatusChanged, this, &CaptureDialog::lockStatusChangedSlot);" does not compile because there are two signals QCamera::lockStatusChanged with different parameters
    Last edited by Al_; 2nd May 2014 at 11:27.

  2. #2
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    Default Re: connect overloaded signal with parameter

    Quote Originally Posted by Al_ View Post
    I prefer to use the more modern signal/slot connect() version as it is typesafe at run-time.
    Even the old connects are typesafe at runtime. What you probably meant is typesafe/typechecked at compile time.

    Quote Originally Posted by Al_ View Post
    Examples:
    • "connect(camera, &QCamera::error, this, &CaptureDialog::errorSlot);" does not compile because there are two QCamera::error functions: the signal "QCamera::error(QCamera::Error)" and the regular function "QCamera::error() const"
    • "connect(camera, &QCamera::lockStatusChanged, this, &CaptureDialog::lockStatusChangedSlot);" does not compile because there are two signals QCamera::lockStatusChanged with different parameters
    You need to provide disambiguation through casting

    Qt Code:
    1. connect(camera, static_cast<void(QCamera::*)(QCamera::Error)>(&QCamera::error), this, &CaptureDialog::errorSlot);
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    Cheers,
    _

  3. The following user says thank you to anda_skoa for this useful post:

    Al_ (2nd May 2014)

  4. #3
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    Default Re: connect overloaded signal with parameter

    Great, thanks for quick reply. Works perfectly! I had played around with QMetaMethod, had tried to typedef; but casting did not come to my mind.

    PS: yes, I meant compile time.

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