Semantics of ^^

Phil Deets pjdeets2 at gmail.com
Tue Dec 8 23:40:44 PST 2009


On Tue, 08 Dec 2009 22:26:10 -0500, Don <nospam at nospam.com> wrote:

> Phil Deets wrote:
>> On Tue, 08 Dec 2009 12:42:33 -0500, Bill Baxter <wbaxter at gmail.com>  
>> wrote:
>>
>>> On Tue, Dec 8, 2009 at 2:32 AM, Don <nospam at nospam.com> wrote:
>>> [snip]
>>>> * If both x and y are integers, and y > 0,  x^^y is equivalent to
>>>>   { auto u = x; foreach(i; 1..y) { u *= x; } return u; }
>>>> * If both x and y are integers, and y < 0, an integer divide error  
>>>> occurs,
>>>> regardless of the value of x. This error is detected at compile time,  
>>>> if
>>>> possible.
>>>
>>> Can you explain why you think that's necessary?  Seems like going too
>>> far towards a nanny compiler for no particularly good reason.
>>>
>>> The fact that 2^^-1 isn't particularly useful doesn't make it
>>> particularly error prone.  No more so than integer division when the
>>> person meant floating point division.  I just find it unexpected that
>>> a language would single out exponentiation for this kind of treatment.
>>>
>>  I was also wondering about this. If it can't be detected at compile  
>> time, is the result 0?
>
> No, it's a compile-time error.

It can't be a compile-time error if it can't be detected at compile time  
like I said in my question. In the code

2^^SomeFunctionFromACModuleThatReturnsInt();

the compiler can't know whether the exponent will be positive or negative.  
When the code runs and a negative result is returned, will the result be  
zero?

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