> On 8 Jul 2016, at 12:03, Leonardo Pessoa <[email protected]> wrote:
> You would have to add some extra code on the compiler to check whether you
> can use that type for your variadics argument and may incur in more changes
> to enable handling different classes possible.
Not really; the variadic call just needs to be treated as if it is an array
literal, at which point the compiler will either match a method or it won't.
The only real difference is that when called as a variadic the compiler will
only match functions with the @variadic attribute. In other words the following
resolve in much the same way:
someMethod([1, 2, 3, 4, 5, 6]) // Looks for a declaration of
someMethod() that can take an array literal
someMethod(1, 2, 3, 4, 5, 6) // Looks for a declaration of
someMethod() that can take an array literal, and has a @variadic parameter
Treating the trailing ellipsis as a shorthand for [Foo] is no different in that
respect, it's just limited to Array only. In other words, if an array literal
cannot be accepted by the parameter, then it cannot have the @variadic
attribute, we'd need a compiler expert to comment but I don't think that should
be that hard to check (concrete types will be checked for conformance to
ArrayLiteralConvertible, and generics will be checked to see if they can be
fulfilled by an Array or some kind of ArrayLiteral type).
Really what it comes down to is a choice between two methods of solving the
array passing problem:
Variadic function treated as regular function with array parameter.
Regular function gains ability to be called (optionally) in variadic style at
call site.
But my preference is for the latter as it eliminates the variadic function
declarations as being some kind of special case, and moves it into a feature of
regular function declarations.
> I would also expect to be able to use dictionaries as variadics with this
> syntax, and that would be confusing too.
This should only be the case I think if you've extended Dictionary with an
ArrayLiteralConvertible initialiser, or you declared your function to take a
generic iterator/sequence/collection with elements of type (Key, Value) in
which case, yes, a Dictionary could fulfil the requirements._______________________________________________
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