Hi,
we encountered the question of how to name parameters in lambda expressions.
For regular functions, the coding style implies that parameter naming
should use camelCase with an "a" prefix, and this is also widely done
this way. The coding style does not say anything specifically
concerning lambda expressions at the moment. Actual uses differ at
least between using the a prefix and using no prefix.
Since in most cases, lambda expressions occur within a regular
function, using the a prefix leads to some ambiguity when reading the
code, as one cannot immediately tell whether an a-prefixed identifier
is a parameter to the lambda expression or to the enclosing function
(which may be captured).
For example, one might have:
bool MyFunction(const nsTArray<Foo>& aFoos, const nsCString &aId) {
if (std::any_of(aFoos.begin(), aFoos.end(), [aId](const Foo& aFoo) {
return aFoo.Id() == aId;
}) {
// do something more...
return true;
}
return false;
}
This is a simple case, where this might not be particularly
problematic, but I find it quite confusing to use aFoo as a lambda
parameter name. Obviously, when not using a prefix, similar
ambiguities with local variable names in the enclosing function may
arise. For some subjective reason, I find this less confusing, but
this may be different for others. Using a different prefix, e.g. l,
leading to calling the lambda parameter lFoo, would resolve this
ambiguity, but one might feel there are too many different prefixes.
While I have some personal preference against the a prefix here, I
think any of these options were acceptable. Maybe this has already
been discussed and concluded before, but not put into the coding style
document?
Simon
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