[jacques_chester]

    bazel build //main:hello-world

I'm sure the double slashes and colon have important differences. It is not obvious what they are.

    cc_binary(
      name = "hello-world",
      srcs = ["hello-world.cc"],
      deps = [
        ":hello-greet",
        "//lib:hello-time",
      ],
    )

It's not instantly obvious why one is :hello-greet and the other is //lib:hello-time.

I could swear I've seen @ floating around as well.

As I said above, I am sure these are all very sensible. But I am just tired of memorising minilanguages embedded in strings. I don't want to any more.

[jkaplowitz]

Completely valid concern not to want to keep memorizing mini-languages.

In this case, the double slashes are absolute "paths" relative to the top of the workspace, and the part after the colon is a relative "path" to another Bazel target.

I put "paths" in quotes because these are meaningfully different from the true filesystem equivalents; avoiding confusion with real absolute and relative filesystem paths is probably why they made their own syntactic mini-language.

[The sibling reply to mine, referencing Piper and Perforce, goes into a bit more detail on the specifics and the origin of the // prefix.]

What would the better way have been for them to do this?

[jacques_chester]

> What would the better way have been for them to do this?

I don't know, off the top of my head (having been on the other side of this conversation, I am aware how frustrating that answer is). But I know I couldn't keep it straight when I was fighting Bazel and that I gave up. And anecdotally I am not alone: I have seen Bazel torn out of multiple projects, sometimes quite painfully.

[jkaplowitz]

Bazel is definitely designed for a very different model than how most of the world works. (I.e., Google's internal model.)

This clearly shows in Bazel's Python support: its internal version (Blaze) gets used quite often with Python inside Google's monorepo, and it works very nicely in that role, but that's a very different way of using Python than approximately the entire rest of the world. It's still Python, to be clear, just everything else is pretty different. ;)

Still, Bazel's model is pretty great if you adjust your brain, tooling, and patterns to it. I accept that most people don't. And some of its preferred usage patterns are more trouble than they're worth in a typical small shop anyway, at least with the usual other tooling one has to integrate with.

Tradeoffs...

[malkia]

Piper, google's source control system has roots in Perforce. In perforce, depot roots are starting with //

The ":" is a bit different, e.g. just "//lib" means "//lib:lib" - e.g. points to the "lib" target in /lib/BUILD file, while "//lib:hello-time" points to "hello-time" target in /lib/BUILD file. So not having the ":name" in "//dir:name" means name="dir" - e.g. "//dir:dir" - at first this is strange, but then you get used to it. Your default target is named after the folder it's sitting in.