Making uniform function call syntax more complete a feature

[Tommi]

On Thursday, 12 July 2012 at 13:19:00 UTC, Thiez wrote:
> It's already quite obvious that the compiler does not obey its 
> own rewrite rules (see 
> http://dlang.org/operatoroverloading.html#compare) Consider 
> opCmp:
>  a < b
> is rewritten to
>  a.opCmp(b) < 0
> or
>  b.opCmp(a) > 0
> Let's assume the first rule is always chosen. According to the 
> very rewrite rule we just applied, this must be rewritten to
>  a.opCmp(b).opCmp(0) < 0
> which must be rewritten to
>  a.opCmp(b).opCmp(0).opCmp(0) < 0
> and then
>  a.opCmp(b).opCmp(0).opCmp(0).opCmp(0) < 0
> and so on, to infinity.
>
> It seems quite obvious the compiler does not rewrite compares 
> on integers or all hell would break loose... The language 
> reference should be more specific about these things.

Quote from 'The D Programming Language' chapter 12.1:
"D’s approach to operator overloading is simple: whenever at 
least one participant in an operator expression is of 
user-defined type, the compiler rewrites the expression into a 
regular method call with a specific name. Then the regular 
language rules apply."

So, assuming opCmp returns integer, then a.opCmp(b) < 0 doesn't 
get rewritten (lowered) any further, because user-defined types 
are not involved.