[webkit-dev] For your consideration: Naming scheme for fooIfExists/ensureFooclearStyleResolver

[Gavin Barraclough]

On Jun 18, 2013, at 10:16 PM, Ryosuke Niwa <rniwa at webkit.org> wrote:

> On Tue, Jun 18, 2013 at 7:20 PM, Simon Fraser <simon.fraser at apple.com> wrote:
> On Jun 18, 2013, at 7:11 PM, Darin Adler <darin at apple.com> wrote:
> 
>> On Jun 18, 2013, at 7:05 PM, Ryosuke Niwa <rniwa at webkit.org> wrote:
>> 
>>> Why don't we call it requireStyleResolver() instead?
>> 
>> I’m warming to this idea. Maybe we can use “require” as a term of art, analogous to the way we use “create”, to mean “create if not already created”.
> 
> Since the fact that it returns a reference implies that it must create something if necessary, the “required” part of the name seems redundant. Why not just
> 	StyleResolver& styleResolver()
> 
> requireStyleResolver() sounds like it would return a bool.
> 
> True. But it's important to differentiate a simple inline accessor and a lazily-create function because it's very easy to write code like:
> 
> if (styleResolver().x())
>     styleResolver().y();
> 
> and incur two function calls when we could have done

OOI Is the lazily-create function not inlined? – I wouldn’t expect to pay two function calls here, since the method is in the header & looks simple enough:

    StyleResolver* ensureStyleResolver()
    { 
        if (!m_styleResolver)
            createStyleResolver();
        return m_styleResolver.get();
    }

I imaging we may perform the branch twice, since it may not be apparent to the compiler that m_styleResolver is non-null after the first call – though I guess this is necessary since theoretically x() could clearStyleResolver.

> StyleResolver& resolver = styleResolver();
> if (resolver.x())
>     resolver.y();
> 
> instead.
> 
> On the other hand, I've started to think that maybe we can simply forbid the former style altogether in the style guide so that we'll never have to think about whether a given function is inline or not.
> 
> - R. Niwa
> 
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