On Aug 6, 2007, at 17:37, Mark Duling wrote:

Kevin Van Vechten writes:

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Why do we have depends_lib, depends_build and depends_run? Why not just a single "depends"? Why does it matter which phase requires the other software? Isn't it enough to know that the other software is required at some point, and so MacPorts should install that other software first?

Depends_build dependencies are only needed if you're actually building the software. They're not needed at all once the software is built and installed. (Think of gcc).

Depends_run dependencies are needed when the software is run, but not necessarily to build the software. (Think of a program that does a fork/exec of /usr/bin/foo at runtime).

Depends_lib dependencies are needed both at build time (for headers and libraries to link against) and at run time (to provide necessary code).

For binary packages, you'd only need to consider depends_lib + depends_run. Even for those building their own software, it makes sense to distinguish since it gives a better sense of what uninstalls might break (i.e. gcc is a depends_build for most projects, but uninstalling it wouldn't interfere with many ports operation).

Thanks, Kevin. I'll review this more closely in a bit and document it in the new guide.

Curiously, even though I fixed the four ports I had installed that required pkgconfig to list it as a build dependency instead of a library, "port uninstall" still won't let me uninstall pkgconfig, saying those four ports depend on it. Oh, I see, I have to reinstall those four ports first. So, for the documentation, another consequence is: if you try to "port uninstall" something, it will prevent you from doing so if any port depends on it via depends_lib, but doesn't complain if a port depends on it via depends_build (and I don't know about depends_run).