[MOAB-dev] Discussion on return type of MOAB routines

[Jed Brown]

"Tim Tautges (ANL)" <tautges at mcs.anl.gov> writes:
> As Jed suggested,
>> if you want to preserve all this context data, we could create an
>> ErrorCode which is a pointer to a real ErrorContext, containing a
>> message and other relevant info. If success, always return NULL, which
>> for most standard compilers should translate to 0 ? Else, look deeper
>> in to the ErrorContext object and print/discard needed info.
>
> But how is that different than passing back an object owning a string?  Most string implementations will have the 
> character part dynamically allocated too, so in practice it should be almost the same.  But the timing information is 
> very different.  I wonder whether that's because the ErrorCode return is POD, which gets optimized differently than when 
> a class is returned?

Presumably you're paying for the std::string copy constructor (copy by
value, involves new dynamic allocation) followed by the std::string
destructor for the original object.  Replace it with a raw pointer and
it'll be fast.  Note that you'll need a way to collect the data behind
the pointer so it doesn't leak if the caller discards it.
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