Idea : Expression Type

[Andrei Alexandrescu (See Website For Email)]

Xinok wrote:
> Functions aren't powerful enough to be used in place of expressions.
> 
> -- Functions can't return references, which prevents you from using them as l-values. The best you can do is return a pointer, which you have to manually dereference.
> -- All of the types in an expression are automatic, including the return type. Getting the parameter types for a function can be simple, but the return type can be difficult.
> -- Functions can't take full advantage of features like conditionals, because conditionals can have two or more possible 'return types'. Functions can only return a single type.

Conditionals always have one return type that can be detected as 
typeof(true? T : U).

The advantage of expression aliases is that indeed there's no need to 
worry for their type. Also, expression aliases work when passing e.g. 
constant expressions to templates because they expand during 
compilation. The disadvantages are that (1) writing statements in the 
replacement expression is not possible, (2) separate compilation is not 
possible.


Andrei