In one of my classes, I created two overloads to opIndexAssign (the second one was made for better performance, because in most cases only one index is used):

public final T opIndexAssign(T value, int[] args ...)
public final T opIndexAssign(T value, int i)

These are allowed by the compiler. But these are not:

public T opIndexOpAssign(string op)(T value, int i)
public T opIndexOpAssign(string op)(T value, int[] args ...)

Seems I cannot overload them just because these are template functions. But I dont see the rationale behind this.

And when I want to make these "final", like this:

public final T opIndexOpAssign(string op)(T value, int i)

the compiler complains because it thinks i want to apply the final keyword to "string op" (why would I? the keyword is at a completely different position). That is kind of strange.

On Fri, 31 Dec 2010 09:09:23 -0500, szali <bszalkai0@gmail.com> wrote:

BTW, this list is generally not used for questions (it's auto-generated from bugzilla reports), d.learn is a better place, but no worries, here are your answers:

> In one of my classes, I created two overloads to opIndexAssign (the
> second one was made for better performance, because in most cases
> only one index is used):
>
> public final T opIndexAssign(T value, int[] args ...)
> public final T opIndexAssign(T value, int i)
>
> These are allowed by the compiler. But these are not:
>
> public T opIndexOpAssign(string op)(T value, int i)
> public T opIndexOpAssign(string op)(T value, int[] args ...)

It's a limitation of the way templates are specified.  To the compiler, both are the same template.

The way around this is to change the template parameters:

public T opIndexOpAssign(string op)(T value, int i)
public T opIndexOpAssign(string op, bool variadic=true)(T value, int[] args ...)

It's a crappy requirement, I think this is a well-known bug.

BTW, you gain very very very little by having both these functions, the variadic one is all you need.

Also, you may have an issue with using a variadic, as I think you can call with zero indexes (not sure how that would look).  You may want to replace both with this one function:

public T opIndexOpAssign(string op)(T value, int idx0, int[] idxN...)

> And when I want to make these "final", like this:
>
> public final T opIndexOpAssign(string op)(T value, int i)
>
> the compiler complains because it thinks i want to apply the final
> keyword to "string op" (why would I? the keyword is at a completely
> different position). That is kind of strange.

All template functions are final.  They cannot be virtual, so even though I feel this is a bug (it should be silently ignored), you can fix it by just removing final.

-Steve

Steven Schveighoffer:

> so even though I feel this is a bug (it should be silently ignored),

Generally silently ignoring attributes is exactly the opposite you want from a modern compiler. See bug 3934.

Bye,
bearophile

On Fri, 31 Dec 2010 10:11:02 -0500, bearophile <bearophileHUGS@lycos.com> wrote:

> Steven Schveighoffer:
>
>> so even though I feel this is a bug (it should be silently ignored),
>
> Generally silently ignoring attributes is exactly the opposite you want from a modern compiler. See bug
> 3934.

In this case though, you are asking for a function which is already final to be final.  The compiler can safely ignore the request because the request is already satisfied.

If you asked for a virtual function to be final, and the compiler ignored the request, I'd say it was bad.

-Steve