[Nix-dev] BuilderDefs

[Michael Raskin]

>Hi,
>
>On 09/11/2011 06:45 PM, Michael Raskin wrote:
>
>> +x@{builderDefsPackage
>> +  , ...}:
>> +builderDefsPackage
>> +(a :
>> +let
>> +  helperArgNames = ["stdenv" "fetchurl" "builderDefsPackage"] ++
>> +    [];
>(snip)
>
>Could you stick to the standard way of writing packages?  That is,
>
>   { stdenv, fetchurl }:
>
>   stdenv.mkDerivation {
>     name = "libmodplug-0.8.8.4";
>
>     src = fetchurl { ... };
>
>     meta = ...;
>   }
>
>That style is easier to read, shorter, uses fewer strange idioms 
>(‘helperArgNames’?), is better documented, and easier to maintain by 

helperArguments reduce code duplication: all standard packages list most
of their arguments twice - as buildInputs and as arguments. Substantially 
editing this list becomes very annoying quickly.

>others (because it is the standard notation).

It is also unpredictable w.r.t. shell variable expansion (a few packages 
where I encountered it seemed impossible to write with setup.sh without
simply writing a big nice builder.sh), it lacks a few predefined things 
that cannot be added without causing full rebuild..

>The purported advantage of builderDefs (making it easier to customise 
>build phases etc.) I haven't really seen in practice ­— stdenv's 
>setup.sh has plenty of customisation mechanisms.

It has weak mechanisms of post-modification: when I commit a tarball version
and actually use VCS-trunk version I need to add something to preConfigure of
the package. 

Of course, its use is usually in user configuration.

Also, there are a few expressions that use topic-specific buildPhases. The 
simplest example is about fonts.