inheriting ctors?

[Philippe Sigaud]

On Fri, Aug 6, 2010 at 21:59, Rory Mcguire <rjmcguire at gm_no_ail.com> wrote:

>
> Here is a possible solution to your problem:
>
> -Rory


I believe you can get the type of A. Isn't it typeof(super) or
std.traits.BaseClassesTuple!B[0] ? B in the latter case being typeof(this)
That way, there is no need for the user to provide A, it's automatically
found by the template.
Warning: I did not test this.

And, we know the constructs are of type 'A function(someTypes)'  [*], so the
'A function' part is redundant.
Hence, the user only needs to provide for the args types and that makes for
a cleaner call.

* either as a list :
    mixin(InheritConstructors!(int, double, string)); // I want to inherit
the constructors taking one type, build me the __ctors for int, double and
string

* or, in the case of multi-parameters constructors, wrap them in a tuple:
    mixin(InheritConstructors!(int, double, Tuple!(int, double)); // I want
super(int), super(double) and super(int, double)

That means iterating on the type list, and determining if the current type
is a tuple or not
* if its a 'normal' type, create the corresponding contructor
* if it's a Tuple, crack it open and get the types, using the .Types alias
std.typecons.Tuples have. Creating a constructor from this typetuple is no
different from creating it for one type.

To determine if something is a std.typecons.Tuple, you cannot use an is()
expression: they do not allow multiple types:

enum bool isTuple = is(T == Tuple!U, U...); // no. U... is not allowed. Hmm,
enhancement request?

So, you can either rely on it having a .Types 'member':

template isTuple(T)
{
  enum bool isTuple = is(T.Types);
}

Pb: that will flag as tuples any type that exposes a ".Types" alias.

Or use a function accepting a Tuple:

template isTuple(T)
{
    enum bool isTuple = is(typeof({
                                   void foo(U...)(Tuple!U t) {}; // this
function accepts only tuples
                                   foo(T.init); // test it
                                  }()));
}

It's ugly as a rat's ass, but it's more solid than the former template.


Philippe

[*] btw, shouldn't that be A delegate(someTypes)???
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