[Interest] How to speed-up chameleons

[igor.mironchik at gmail.com]

Hi.

What do you suggest?

From: Romain Beaumont 
Sent: Wednesday, June 11, 2014 5:12 PM
To: Keith Gardner 
Cc: igor.mironchik at gmail.com ; interest at qt-project.org 
Subject: Re: [Interest] How to speed-up chameleons

Hi, 
Why do you need to use Qt signals/slots ?
Isn't there something more appropriate to this task ?



2014-06-11 15:36 GMT+02:00 Keith Gardner <kreios4004 at gmail.com>:

    I have one question to you. Why new syntax of QObject::connect() improve performance for a 5%.

    I mean that if in code change

    connect( sender, SIGNAL( signal() ), receiver, SLOT( slot() ) );

    to

    connect( sender, &Sender::signal, receiver, &Receiver::slot );

    then code works faster... Why? May be somebody know the answer, I don’t want to read Qt’s code for the answer on this question.

  I would guess would be that the first connect is performing a string lookup and validating the arguments at run time.  SIGNAL and SLOT are taking the macro parameters and turning them into character arrays.

  The second connect is working with function pointers which allows for the compiler validate their existence and ensure that the arguments are compatible at compile time instead of run time.

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