Re: [boost] formal review of Switch library ends tomorrow (Wednesday, January 9th) - reviews needed

From: Tobias Schwinger (tschwinger_at_[hidden])
Date: 2008-01-09 21:26:28

Reposting to boost.devel.

Steven Watanabe wrote:
> AMDG
> 
> Tobias Schwinger <tschwinger <at> isonews2.com> writes:
> 
>> As pointed out in other posts I think the default default case behavior
>> should be changed not to throw but to use the default constructor if no
>> default case function object is specified.
> 
> Will do.
> 
>> A default case function object returning 'void' should be assumed (and
>> 'assert'ed) not to return in a context where a (non-void) result is
>> expected (implementation hint: the built-in comma operator allows void
>> arguments and an overloaded comma operator doesn't).
> 
> Personally, I'd rather just forbid a default that returns void
> when the return type is non-void.  

The rationale was to allow non-returning default function objects that
work regardless of the type (such as 'throw_'). It's probably not that
important...

> I don't think the comma operator
> is a completely fool-proof way to detect void. 

It is.

> It could cause an
> ambiguity if the other type also defines an overloaded comma operator.

No, because the operator is binary and one operand can have a reserved
type which is only internally used by the test code.

Regards,
Tobias