Do type of cast affects execution speed?

Question

I wonder if there is any difference in execution speed between:

Object( e.target ).labelTextID

and

MovieClip( e.target ).labelTextID

e.target in that case is a MovieClip, but it doesn't matter.

score 2 · Accepted Answer · answered Sep 17 '13 at 14:28

There aren't any difference. Take a look on this sample code:

        var obj:Object = new MovieClip();
        var v1:Object = Object(obj);
        var v2:MovieClip = MovieClip(obj);

Both type castings produce the same op codes:

        _as3_findpropstrict Object
        _as3_getlocal <1> 
        _as3_callproperty Object(param count:1)
        _as3_coerce Object
        _as3_setlocal <2> 

        _as3_findpropstrict flash.display::MovieClip
        _as3_getlocal <1> 
        _as3_callproperty flash.display::MovieClip(param count:1)
        _as3_coerce flash.display::MovieClip
        _as3_setlocal <3>

The conclusion is also confirmed by benchmark:

    var obj:Object = new MovieClip();

    var v1:Object, v2:MovieClip, i:int;
    var t:uint = getTimer();

    for(i = 0; i < 1000000; i++)
        v1 = Object(obj);

    trace("Object: ", (getTimer() - t));

    t = getTimer();
    for(i = 0; i < 1000000; i++)
        v2 = MovieClip(obj);

    trace("MovieClip: ", (getTimer() - t));

output:

Object:  92
MovieClip:  90

while the cast itself takes the same amount of time, how you use it afterwards will affect your speed, i.e. it's generally quicker to access variables/methods through specific class instances rather than generic (`Object`) — divillysausages, Sep 17 '13 at 21:13

score 1 · Answer 2 · edited May 23 '17 at 11:50

1

In terms of what type of object you cast to, I cannot be sure, but in terms of how you are doing your casting I would take a look at this answer: https://stackoverflow.com/a/14268394/1346390

The TLDR of it is, use "as" for casting, since it's both faster and safer, since it throws a TypeError if it fails.

edited May 23 '17 at 11:50

Community

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answered Sep 17 '13 at 14:25

Valentin

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score 0 · Answer 3 · answered Sep 17 '13 at 14:29

0

There must be no difference between this cast. In both cases the compiler is instructed to explicit cast the e.target no matter of type of e.target.

answered Sep 17 '13 at 14:29

Azzy Elvul

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Do type of cast affects execution speed?

3 Answers3