zack at kde.org
Sat Oct 1 10:54:04 BST 2005
On Friday 30 September 2005 18:17, you wrote:
> My argument for flatten-where-possible is based on the need for extra
> allocations and indirections.
Which as people have already told you makes absolutely no difference and
> I don't know what you mean by loss of flexibility: I never proposed
> getting rid of the d pointer - only not using it when possible.
No, that's not what I meant. Once you have members in the class you
can't get rid of them, that's a loss of flexibility. And the argument
that these classes are stable doesn't hold. Stable != won't change
anymore. In our field saying that some code won't ever be changing is
almost saying no one will be maintaining it anymore and it's
> > Also if you want real world example of what kind of effect porting
> > of Qt 3 app to Qt 4 has look at:
> > http://blogs.qtdeveloper.net/archives/2005/08/24/qsa-120/
> Nice anecdote, but beside the point.
I'm not sure whether you have some identity crisis which I should be
aware of but if I wanted to reply to your email only, top of that
email wouldn't say:
"On Wednesday 28 September 2005 22:31, Stephan Kulow wrote:"
Maybe you're going through one of the "Wanna be like Coolo" phases, but
trust me I know him and you're not it. So since he was complaining
about the speed of Qt 4 this part was right on the money.
> Even without a convenient
> algorithm change, if you start with a non-empty d-pointer structure
> and you flatten it out, you will go faster.
Oh, sure, you'll also go faster if you code it all in one big main
function or even better write it in assembly. Hell, machine code all
the way and we'll be flying...
The bottom line is this: people have shown you that the performance
difference is negligible so flattening d-pointers makes no difference.
The performance argument is bogus. And unless you can provide
performance measurements of where it really matters you don't have an
argument. At all.
Every man for himself, all in favor say "I"
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