[MOAB-dev] portability issue/question

[Tim Tautges]

Shouldn't this go away once we start using the namespace'd headers?

- tim

On 08/02/2010 10:24 AM, Paul Wilson wrote:
> Jason Kraftcheck wrote:
>> On 07/29/2010 07:00 AM, Paul Wilson wrote:
>>> Hello,
>>>
>>> I am integrating MOAB/DAGMC into a c++ code that includes a header that
>>> defines index() as a macro, apparently through some combination of
>>> system headers.
>>
>> That's really ugly. It comes from a system header???
> I tracked it down to an X11 header: X11/Xos.h. It appears to want to
> provide index() and rindex() as aliases for strchr() and strrchr(). The
> comments suggest that some systems already provide these and it only
> defines them if they are not already defined. However, string.h does
> define these, just not as macros.
>>
>>> This creates a problem with including moab/Range.hpp
>>> because it attempts to define a member function index().
>>
>> It also has an argument named 'index' in one spot.
> This is not a problem since the macro is a function macro (?) and
> requires 2 arguments. It complains about the existence of index() with a
> single argument.
>>
>>> Fortunately it
>>> creates a compile time failure because the signature of the
>>> Range::index() is different from the macro, otherwise who knows what
>>> would happen???
>>>
>>> I haven't bothered to track it down yet, but the short solution has been
>>> to add the following immediately prior to the include:
>>>
>>> #ifdef index
>>> #undef index
>>> #endif
>>>
>>> I have resisted committing this to the repo because it seems like a
>>> little presumptious/overbearing. Any other solutions?
>>>
>>
>> In general, I can't think of a better way to work around really poor
>> macro name choices like this. Undef whatever you need to right after
>> including the offending header. Or if you need to include the
>> offending header in more than one place, write a wrapper header that
>> includes it and any necessary #undefs.
>>
>> The ideal solution would be to fix the offending header, but I assume
>> that isn't an option.
> I think the X11 header needs to be fixed but that us outside our scope.
> On a different note, I can make this go away by changing the order that
> things are included, in this case.
>
> Paul
>

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              Tim Tautges            Argonne National Laboratory
          (tautges at mcs.anl.gov)      (telecommuting from UW-Madison)
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