ATTN Derelict Users and Package Maintainers

[Mike Parker via Digitalmars-d-announce]

On Wednesday, 31 December 2014 at 10:26:18 UTC, OlaOst wrote:
> Works fine for me on windows, after running 'dub upgrade'.
>
> I tested the SharedLibVersion with a 2.0.1 and a 2.0.3 SDL dll.
> With the 2.0.3 dll, I could call functions added in SDL 2.0.2 
> even when using SharedLibVersion(2, 0, 0) - is this intended 
> behaviour?

Yes. I guess I wasn't clear about this in my blog post. This 
isn't telling Derelict to "only load 2.0.0 functions and ignore 
the rest." It's instead saying, "Don't throw any exceptions if 
functions from 2.0.1 and 2.0.2 are missing." If you give it a 
2.0.1 DLL, it will load 2.0.1 functions. Give it a 2.0.2 DLL and 
it will load 2.0.2 functions, regardless of what you pass in 
SharedLibVersion. But now you can happily load 2.0.0 and not 
worry about SymbolLoadExceptions. See below for the big caveat.

>
> With the 2.0.1 DLL I got the expected 'Failed to load symbol' 
> error without using the SharedLibVersion, or using 
> SharedLibVersion(2, 0, 2).
>
> However, if I call one of the functions added in SDL 2.0.2 when 
> loading the 2.0.1 context, I get an 'object.Error@(0): Access 
> violation' error. Would it be possible to get a more 
> informative error message in this case?

That's not a Derelict error message. That's coming from the 
system. Keep in mind that Derelict binds to shared libraries via 
function pointers, so if any functions aren't loaded, the 
corresponding function pointers will be null and you'll get an 
Access Violation as a result. You should *only* use the 
SharedLibVersion to specify your minimum required version, not as 
a "give me whatever you've got" kind of thing like OpenGL. If you 
need 2.0.1 functions, but not 2.0.2, then you should be passing 
SharedLibVersion( 2,0,1 ), not 2,0,0.

I also recommend that you get in the habit of always passing a 
SharedLibVersion to the load method so that you can future-proof 
your app. It will always load if you upgrade to take advantage of 
bug fixes, no matter which new API functions are added. If yo 
don't do this, then an update will cause it to stop loading older 
versions and only load the newest. In fact, I would love to 
remove the existing load methods completely, but I do need to 
maintain back compat.

>
> Highly appreciate your work on Derelict, BTW.

Thanks! And thanks for trying out the new stuff.