yank unary '+'?

[Andrei Alexandrescu]

Walter Bright wrote:
> Andrei Alexandrescu wrote:
>> Walter Bright wrote:
>>> Andrei Alexandrescu wrote:
>>>> Is there any good use of unary +? As an aside, Perl programs do use 
>>>> it occasionally for syntactic disambiguation :o).
>>>
>>> An internet search reveals:
>>>
>>> 1. symmetry
>>>
>>> 2. compatibility with C and many other languages that use it
>>>
>>> 3. used with operator overloading to convert a user defined type to 
>>> its preferred arithmetic representation (a cast can't know what the 
>>> 'preferred' type is)
>>>
>>> 4. to create DSL languages, like Spirit, as Kenny points out
>>>
>>> 5. to coerce default integral promotion rules (again, cast(int) won't 
>>> always produce the same result)
>>>
>>> 6. to visually emphasize that a literal is positive
>>>
>>> I say leave it in.
>>
>> I am completely underwhelmed by 1-6 and have strong arguments against 
>> each, but "frankly, my dear" I have bigger problems than that. I have 
>> exactly zero valid reasons I could mention in TDPL, and that's my 
>> litmus test. I find the operator utterly useless. If '+' stays in, 
>> then call it horsetrading but the occasionally useful '^^=' must also 
>> be in.
> 
> Think of it like the "bool" operator overload. bool gives a direct way 
> for user defined times to be tested for if statements, etc.

If I think of it that way, that doesn't look too good. The bool operator 
overload has been an unqualified and admitted failure for C++. The hacks 
used to avoid that failure are very ingenious; none was within the realm 
of what the language had planned or intended.

> Similarly, 
> U+ gives a direct way for user defined types to be converted to their 
> most desired arithmetic type.

Code that uses +a to convert a to another type? I'd consider that worse 
than a hack and worse than incompetent - it's downright malicious.


Andrei