Split a large BUILD file into multiple files

[linuxerwang]

Hi,

I have a very large BUILD file for third_party/go, is it possible to split it into multiple files and let plz to load them while treat them as one file?

Thanks.

[chrisnovakovic]

You could probably do it with subincludes, but I wouldn't recommend it. There's a pretty clean alternative if you use go_module, though - you could split the module import paths on forward slash characters and have a separate intermediate directory for each component, e.g.

## third_party/go/github.com/agnivade/levenshtein/BUILD

go_module(
    name = "levenshtein",
    module = "github.com/agnivade/levenshtein",
    version = "v1.2.0",
)

You can then refer to the module as //third_party/go/github.com/agnivade/levenshtein. You'd have a lot of BUILD files this way, but each one would be tiny.

It doesn't work out as cleanly as this if you use go_repo, because go_repo defines a subrepo inside the package containing the go_repo target definition whose name is derived from the module parameter, and the module is built inside that subrepo. In this case:

## third_party/go/github.com/agnivade/levenshtein/BUILD

go_repo(
    name = "levenshtein",
    module = "github.com/agnivade/levenshtein",
    version = "v1.2.0",
)

you'd end up with the module at ///third_party/go/github.com/agnivade/levenshtein/github.com_agnivade_levenshtein//:levenshtein - rather unwieldy.

There shouldn't really be a performance problem associated with third_party/go/BUILD being so large, though - if the problem is one of maintenance, you might want to give Puku a try.