Rational of some DMD decisions

[Ali Çehreli via Digitalmars-d-learn]

On 02/08/2015 01:05 PM, Robin wrote:

> the postfix inc and decrement expressions are
> inherited from BinExpr (binary expression) which define their second
> expression to be an integer expression with a value of 1.

Post-increment cannot be overloaded in D. It is always implemented in 
terms of pre-increment (or +=):

   http://dlang.org/operatoroverloading.html

Although I can't find it on the spec, I think it used to be spelled out 
that pre-increment (and post-increment) could be the equivalent of "+= 
1". I am pretty sure about that because my notes say so! :p (because I 
based everything on what I knew to be correct at the time).

   http://ddili.org/ders/d.en/operator_overloading.html

Quoting myself:

"if an opBinary overload supports the duration += 1 usage, then opUnary 
need not be overloaded for ++duration and duration++. Instead, the 
compiler uses the duration += 1 expression behind the scenes. Similarly, 
the duration -= 1 overload covers the uses of --duration and duration-- 
as well."

Perhaps that's why the compiler uses a binary operator for post-increment.

Ali