[Nix-dev] Mirrors for fetchurl & Multiple versions

[Michael Raskin]

Wouter wrote:
> Hi,
> 
> I sometimes have problems with unavailable sources.
> 
> I think we should have the possibility to express mirrors:
> 
> fetchurl {
>                urls = [ 
> ftp://freepascal.stack.nl/pub/fpc/dist/i386-linux-2.0.4/fpc-2.0.4.i386-linux.tar 
> 
>                            
> ftp://ftp.chg.ru/pub/lang/pascal/fpc/dist/i386-linux-2.0.4/fpc-2.0.4.i386-linux.tar 
> ];
>                sha256 = 
> "0b2szv2anbf58h4i5mlph93afv9qdx6i0jqggba04d3anjbl9gfy";
> };
That is so already.

> ----------------
> currentVersion = getVersion "2.0.6" versions
> 
> versions = [
> {              version = "2.0.4";
>                urls = [ 
> ftp://freepascal.stack.nl/pub/fpc/dist/i386-linux-2.0.4/fpc-2.0.4.i386-linux.tar 
> 
>                            
> ftp://ftp.chg.ru/pub/lang/pascal/fpc/dist/i386-linux-2.0.4/fpc-2.0.4.i386-linux.tar 
> ];
>                sha256 = 
> "0b2szv2anbf58h4i5mlph93afv9qdx6i0jqggba04d3anjbl9gfy";
> }

> and really destructively update or create new expressions when a new 
> version does need different things dependencies or patches.
Better create new. I'd say "revert, if useful, fork expression using,
say, selectVersion" seems better.