Mike Stump <[EMAIL PROTECTED]> writes: | On Jul 14, 2006, at 4:03 PM, Gabriel Dos Reis wrote: | > What that concretely means is that it alienates, for example, codes | > based on Factory desigbn pattern using typeinfo objects. | | I'd love some input from the MS VC++ programming crowd on this issue.
yes, that will be helfpul. If I understand correctly, MS VC++ does not use the mangle name, so it would be interesting to hear how they implement operator== and before() for type_infos. | I don't see how they get past this issue. I've had some claim, but | it's a feature, not a bug. | | The basic question is, are two unrelated types in different dlls the | same, just because they have the same name? How do you prevent them | from being the same? it has been a kind of implicit garantee that two classes with external linkage and with same mangled names refers to the same type. Implementations have used that property -- which "leaks" into user codes via type_info::operator== and type_info::before. My primary concern is to what extent that guarantee continues to hold with the visibility stuff and without alienating coding patterns. When __GXX_MERGED_TYPEINFO_NAMES is defined, there is no problem as things get separate addresses and comparisons are done on addresses. Your earlier suggestion to discontinue support for !__GXX_MERGED_TYPEINFO_NAMES may be a way out, unless a scheme outlined by Geoff is implemented (that seems unlikely, as it is complicated). -- Gaby
