Transition for removing functions from Object [Compiler devs in particular, please read]

[Kenji Hara]

2013/5/27 Jonathan M Davis <jmdavisProg at gmx.com>

> 1. You can't do UFCS with overloaded operators, and opEquals and opCmp are
> overloaded operators. In general, I think that it would be bad to be able
> to
> overload operators via UFCS (especially with functions that are as core as
> opEquals and opCmp), but if we could at least make it so that the compiler
> allowed it in this case until the deprecation process has been completed,
> then
> these functions could be UFCS-able.
>

Class objects and '==' (equality operation) is already treated specially.
Even if a class object has opEquals method (currently Object class has
opEquals, so it's always true), equality operation c1 == c2 is always
forwarded to object.opEquals(c1, c2). As well we can also forward
comparison operator to object.opCmp specially.


> 2. super doesn't work with UFCS. Take this code for example
>

As Lionello already mentioned, this is not an issue.

3. The override keyword makes it so that making those functions free
> functions
> will break all code everywhere that uses them. override is fantastic for
> catching changes in class hierarchies so that you can fix your code when
> base
> classes change, but it does not give us a good deprecation path. So, if we
> were to make these functions free functions, the compiler would have to be
> adjusted so that in this particular case, it gave a message about it (and
> not
> a warning, as that would cause code to break with -w) rather than giving an
> error. I do think that this _should_ give an error normally, as you'd no
> longer be overriding anything, but we need to be able to not make it an
> error
> in this case if we want a smooth transition. override is intended for
> catching
> bugs quite loudly and not for smooth deprecation paths.
>

In this case, compiler should stop reporting "does not override any
function" error.
If -w switch is on, the redundant override keyword usage would be warned.

Kenji Hara
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