[Cfp-interest] exceptional macro

[Jim Thomas]

I’m worrying about use of compound statements as a macro argument. There’s a discussion about this at

http://stackoverflow.com/questions/17182877/is-it-ok-to-use-a-code-block-as-an-argument-for-a-c-macro

How serious is the restriction on the use of unguarded commas? E.g., how would multidimensional arrays be expressed? Are there other restrictions?

-Jim

On May 14, 2014, at 2:01 AM, Mike Cowlishaw <mfc at speleotrove.com> wrote:

> 
>> FE_EXCEPTIONAL( expression or compound statement, 
>>                 exception1, exception2, ...)
> 
> Rather than having the multiple arguments, perhaps it could be simply
> 
>  FE_EXCEPTIONS( expression )
> 
> which returns the exceptions raised in the evaluation of the expression (or
> compound statement if that's allowed), ORed together.  (Assuming the exceptions
> & subexpressions are defined to be bit-unique.) 
> 
> 
> Then one might write:
> 
>  if (FE_EXCEPTIONS( p/q | FE_UNDERFLOW )) {whatever}
> 
> or
> 
>  x = FE_EXCEPTIONS( a=p/q | FE_UNDERFLOW ) ? a : sNAN ;
> 
> etc.
> 
> Mike
> 
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