[Scons-users] Compact notation

[Dirk Bächle]

Hi Andrew,

On 12.12.2016 16:50, Andrew C. Morrow wrote:
>
> Right, that is definitely an option. However, I was hoping to capitalize on the logic for Append, Prepend, and more importantly
> AppendUnique and PrependUnique.
>
> How does the expansion of keyword arguments to a Builder work?
>

a so-called "override" environment gets created. It's a proxy object that will hold a reference to the original env, and for all 
touched/changed values the "shadowed" value in the OverrideEnvironment is accessed instead. During initialization of the current 
Builder, the (**overrides) part from the parameter list gets copied to the new environment, but a "subst" is executed on each of its 
values.
Unfortunately, it's only the SCons.Subst.scons_subst_once() method...that doesn't support callables, I'm afraid. :(

Looks like dead-end...we probably have to extend the API for supporting your use case.

Best regards,

Dirk