yank unary '+'?

[Don]

KennyTM~ wrote:
> On Dec 7, 09 00:23, Andrei Alexandrescu wrote:
>> Is there any good use of unary +? As an aside, Perl programs do use it
>> occasionally for syntactic disambiguation :o).
>>
>> Andrei
> 
> Yes, when you want to port the Boost Spirit parser :o) (OK that's an 
> abuse.)
> 
> Well the unary + can help to emphasize "it's a positive number", and 
> 1.0e+10 is already a form of "unary +" (not the operator).
> 
> Removing the unary + doesn't lose much, but it doesn't gain much either, 
> and with it already present in all other languages, I don't see a good 
> reason to change it.

I think + should be added to the syntax for numeric literals, and in all 
other cases unary + should be dropped.
Ie,
x = +0.78; should remain legal.
But
y = +x;  should not.
And likewise,
x = +(+0.78); should be illegal.

Overloading + is odd, too. Currently:
+x;
creates a "has no effect" error if x is a built-in type. But if x has an 
overloaded unary +, it might have side-effects. So it useful ONLY for 
operator abuse!