On Jan 6, 2014, at 13:49 , Geoffrey Garen
<[email protected]<mailto:[email protected]>> wrote:
Let me try to clarify with two more motivating examples:
(1) Nodes.cpp:
FunctionParameters::FunctionParameters(ParameterNode* firstParameter, unsigned
size)
: m_size(size)
{
unsigned i = 0;
for (ParameterNode* parameter = firstParameter; parameter; parameter =
parameter->nextParam()) {
auto pattern = parameter->pattern();
pattern->ref();
patterns()[i++] = pattern;
}
}
If I had to describe this algorithm in English, I’d say, “Collect and retain
all the [auto] from the list of parsed parameters.” I think that explanation
would be stronger if “[auto]” were a concrete noun.
Does anybody prefer auto in this context? If so, why?
While I wouldn't say that I prefer auto here, it doesn't really bother me in
this example. Personally, I would read that as "Collect and retain all of the
patterns from the list of parsed parameters", and I'd say it the same way if
auto had been an explicit type.
(2) ApplyStyleCommand.cpp:
auto children = elementChildren(*dummySpanAncestor);
for (auto child = children.begin(), end = children.end(); child != end;
++child) {
if (isSpanWithoutAttributesOrUnstyledStyleSpan(&*child))
toRemove.append(&*child);
}
I don’t understand why we’re &*’ing here. That’s a surprising idiom I haven’t
seen before, which I would expect to be a no-op. My first question when reading
this is, “What is the type of ‘child’, such that I would need to &* it?”.
Is this "&*child” obvious to everyone else?
It's actually pretty obvious to me, but I've been spending a lot of time with
similar iterators lately. I don't think it's that much clearer without the
auro. I've definitely found this to be confusing in the codebase much before
auto entered the picture. (In this case, I'd argue strongly for using an
accessor method on the iterator or a temporary variable)
- Bem
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