Re: Finding Dependencies at Run Time

[Peter Polidoro]

> Remember the difference between inputs and propagated inputs: 
> they're the same, but when you create a profile, inputs are not 
> part of the
> profile (so they need a direct store reference, such as RPATH or 
> a wrapper), whereas propagated inputs are part of the profile, 
> so an
> environment variable allows to find them.

Thank you for patiently explaining, I think I am starting to 
understand now, but please correct me if I am still wrong.

So there is package build-time, profile build-time, and run-time.

Wrappers should be used to set environment variables when the 
value can be determined at package build-time, such as absolute 
paths to inputs.

Search paths should be used to set environment variables when the 
value will be determined at profile build-time, such as relative 
paths to either propagated-inputs or packages that also installed 
in the same profile, but not listed explicitly as 
propagated-inputs to the package declaring the search paths.

I am still a little unclear about the difference between 
search-paths and native-search-paths, though. If not 
cross-compiling then they act the same? If you are 
cross-compiling, though, then it only finds packages that are 
listed as native-inputs to the package declaring the search paths? 
Native-inputs are not normally installed in a profile, though, 
correct? Does that mean native-search-paths will only be found 
when using a development shell when cross-compiling?

I guess I do not properly understand cross-compiling. So when 
cross-compiling, there is a package build-time, where you are 
building packages for a target architecture on a host machine, 
profile build-time, where you are building a profile on the 
target, and run-time, when you are running on the target? If 
search-paths and native-search-paths are determined at profile 
build-time, how do they behave differently on the target machine?