On May 5, 2020, at 14:21, Nikita Popov <[email protected]> wrote:
>
> Another is to allow specifying the public parameter name and the private
> parameter variable name separately, as is possible in Swift. This would
> allow changing "parameter" names arbitrarily, without breaking the public
> API. This would be a pretty direct counter to your concern, but I'm not
> really sure that your concern is important enough to warrant the additional
> weight in language complexity. I've never used Swift myself, so maybe this
> is actually awesome and I just don't know it.
>
> Regards,
> Nikita
The proposal in my earlier email is very much inspired from Swift. I think
having distinct outside and inside names helps greatly with creating expressive
and readable APIs. The most expressive name for a thing might differ greatly
between inside and outside contexts. Also, the name of a parameter as used by
the inside of a function should be an implementation detail; there's no reason
it should have to be exposed to the outside.
For example, Swift's Array has the following two methods (slightly simplified):
func firstIndex(of element: Element) -> Int?
func firstIndex(where predicate: (Element) -> Bool) -> Int?
You call them like:
array.firstIndex(of: someElement)
array.firstIndex(where: { $0 == someElement })
From the outside, firstIndex(of: ...) is more readable than firstIndex(element:
...) because it reads more like natural language. Same with firstIndex(where:
...) vs. firstIndex(predicate: ...). On the inside, calling it "element" and
"predicate" help you focus on what it _is_, without worrying about calling it
something that also retains meaning to callers.
If you at some point decided to have a mass-renaming of "predicate" to "test",
you could change that everywhere in your library without forcing any sort of
change to users, because predicate is "on the inside". And both of them
starting with 'firstIndex(' gives them a clear relationship; they generally do
the same thing, just with a type of input.
With php currently, you would probably implement those as:
function firstIndexOfElement($element)
function firstIndexWithPredicate($predicate)
$collection->firstIndexOfElement($element);
$collection->firstIndexWithPredicate($someCallable);
But I think that's more wordy, and now you have either a BC break or need to
add a new function if you decided to rename all instances of "predicate" to
"test".
A more readable API might look like this:
$collection->firstIndex(of: $element);
$collection->firstIndex(where: $someCallback);
which is less typing, presuming your IDE didn't offer autocomplete for you
anyway.
-John
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