Re: [Gnash-dev] [patch] Get rid of warning in LineStyle.cpp

[Benjamin Wolsey]

> I'm not sure I fully understand what is going on here, but I believe
> it is related to implicit conversions and temp objects created when
> returning the _color object.

> The change remove the need for some of the temporary objects that need
> to be created and copied around when rgba.color() is used by GetColor,
> and I believe it is good coding style to avoid forcing the compiler to
> create more object that necessary.
> 
> Is this the correct fix?  Anyone understand why it is needed?

It doesn't sound like it; passing by value is generally less
accident-prone than using references, and in this case pretty friendly
towards compiler optimizations. As a rule we should try to pass simple
data structures by value; an rgba object is half the size of a pointer
on some platforms and trivial to copy.

The aliasing rule concerns the way objects may be accessed through
pointers of a different type, which in some circumstances can lead to
the original variable being optimized out. It seems to me that the
problem is more internal to boost::variant.

I don't think it's a good idea to change code to fix a warning that we
don't properly understand, particularly as the change may make the code
less useful without necessarily fixing anything.

bwy

-- 
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The current release of Gnash is 0.8.8
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Benjamin Wolsey, Software Developer - http://benjaminwolsey.de
C++ and Open-Source Flash blog - http://www.benjaminwolsey.de/bwysblog

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