Make public headers C++-compatible

[glebm]

Allow #include <SheenBidi.h> in C++ without having to wrap it in extern "C".

[glebm]

@mta452 Could you please take a look at this and my other 2 PRs? They make it easier to use SheenBidi in C++.

[mta452]

This was raised previously in issue #7 as well. However, I intentionally want to avoid adding support for other languages in the main library itself to keep things simple. I feel it makes more sense to handle such cases in the target language.

[mta452]

Can you please discuss the ideas in a ticket before actually starting the implementation? It would be beneficial to discuss the pros and cons beforehand.

[glebm]

I feel it makes more sense to handle such cases in the target language.

C and C++ are different languages but are part of the same ecosystem.
As this is the only thing needed to achieve C++ compatibility, C libraries generally do this.

For example: all GNU libraries (e.g. gettext), SDL, Linux support libraries (e.g. liburing), etc.

This makes it easier for C++ users and does not have any maintenance overhead. On the other hand, as this library becomes more popular (and I believe it will), some maintenance effort will be spent replying to issues that people open about this.

This is not a major issue of course but it'd be nice to not have to explain to C++ developers (who may not even be familiar with extern) that SheenBidi needs special handling.

Can you please discuss the ideas in a ticket before actually starting the implementation? It would be beneficial to discuss the pros and cons beforehand.

Sure, for the future PRs. Though often having the code makes the discussion easier and makes the effort needed for the implementation clearer.

[mta452]

I'm open to adding support for extern "C" in public headers. But it cannot be just plain blocks of #ifdef ... #endif. Maybe putting them in reusable macros would be a better idea.

[glebm]

The plain ifdef blocks are what's usually used.

We could define something like this in SBBase.h instead:

#ifdef __cplusplus
#define SB_EXTERN_C_BEGIN extern "C" {
#define SB_EXTERN_C_END }
#else
#define SB_EXTERN_C_BEGIN
#define SB_EXTERN_C_END
#endif

I don't think it's necessarily worth it but if you prefer it I can update this PR to use these macros

[glebm]

Changed to macros and retargeted to develop

[mta452]

Thanks, looks good to me 👍