opCast using in template struct

[Era Scarecrow]

On Thursday, 18 October 2012 at 23:51:44 UTC, Timon Gehr wrote:
>If the issue _is_ with the signature, then the compiler should 
>tell you. That is the (secondary) job of the compiler.

  But not everything is parsed/compiled if it doesn't match the 
constraints, especially template functions. Sometimes I wish I 
had more information of what signatures it generated, what it 
compared against, and why each of them were disqualified; But 
that's regarding more complex stuff.


> That is a lot better, but what if the typo is within the first 
> 3 characters? :o)

  If the beginning doesn't match 'op(Op)?[A-Z]', then you can't 
safely guess it was ever intended to override operators.  If it 
has the keyword override then you know in a class it's 
polymorphic, however in a struct.... Hmmm...  i don't know.

  Maybe a small suite list of tests that go through a few dozen 
templates and tells you what a struct qualifies for, like ranges, 
random access, forward/reverse, infinite. Etc. Might be more 
informational but if you expect you struct to do something and it 
doesn't qualify then you have a better idea at least of what is 
wrong.