Pkg3: OS-specific dependency support

[StefanKarpinski]

JuliaLang/Pkg.jl#165

[StefanKarpinski]

Not doing this for 0.7/1.0—see this comment on the upstream issue.

[JeffBezanson]

Good, I really think that's the right decision.

[StefanKarpinski]

Did you read my linked comment before throwing a confused face on there, @ararslan?

[ararslan]

I did.

[StefanKarpinski]

Ok then.

[ufechner7]

A bad decision. This is really a basic piece of functionality for a package manager. Its stupid not to have it in 1.0 version. Who can afford to support three operating systems? I don't have a Mac, and just buying one because I want to develop Julia packages is a bit expensive.

[StefanKarpinski]

I'm not sure where you're getting the idea that you need to buy a Mac. Nobody is forcing you to do that. All this is "forcing" you to do is install the Homebrew package even though it won't do anything on your Windows or Linux system. In exchange, manifest files are portable instead of only working on the system where you generated them. Again, did people actually read my comment?

[ufechner7]

Well, this issue is about OS-specific dependency support. Without this I think I have to support at least three OS. Ok, you say there is a work-around that makes it also possible not to do that. But this doesn't sound like a clean solution to me. It makes me feel very uneasy.
And yes, I was reading all of the discussion. My main experience with package mangers so far is Conda (for Python). I was very happy because I had the impression that Pkg is much better than Conda, but now I have my doubts. :(

[StefanKarpinski]

What is the specific thing you think this decision is forcing you to do?

[ufechner7]

It forces me to think about the compatibility of my packages with Windows and Mac even if I want to release them for Linux only first.

[DilumAluthge]

It’s a very clean solution. If you are developing a non-OS specific package, you literally don’t have to do anything. If you are developing an OS-specific package, all you have to do is detect the OS in your `deps/build.jl` file - e.g. if you have a Linux-specific package, wrap your build code inside an `if is_linux() ... end``` block, and then `build.jl` will do nothing on non-Linux systems.

[ufechner7]

Thanks for your explanations. Lets see how that works in practice.