On Tue, 13 Nov 2007, Sam Liddicott wrote:
> Michael Van Canneyt wrote:
> > On Tue, 13 Nov 2007, Graeme Geldenhuys wrote:
> >
> > > * They tend to be slow compared no native types. In
> > > Delphi 6 they were very slow. How does it compare
> > > in FPC 2.2.0?
> > >
> >
> > They are slower than native types, there is no way around this.
> > Almost each and every operation involving variants has some implicit calls
> > to variant support routines.
> >
> If the variant type is the correct type, no casts are done and the whole thing
> is very quick.
Exactly: IF.
this means
a) Check if. This by itself involves a call to a helper routine.
b) convert if not the same
With native types it's just a straight copy.
> > You should see that it is more than double the size.
> > If that doesn't convince someone that variants are SLOW, then I don't know
> > what will. Use -al for compiler options.
> >
> Twice as big doesn't mean slow at all.
Just have a look at the code before saying that :-)
> Most of the extra code covers different branches based on the variant type,
> most of the extra code is NEVER used but there "in case" because, as you say,
> pascal is a type safe language.
It must be checked, each time over and over again. Just look at the code.
> I would much rather have pascal manage the variant and conversions for me than
> I have to manage it and get it wrong.
The point is that you don't need to do conversions when using typed variables.
Michael.
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