this post was submitted on 08 Nov 2023
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Rust
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It is not that tricky if you shift your perspective. Rather than thinking about files importing files (like you would in other languages), think about the crate as a tree of modules. Then the rules are simple.
main.rs
andlib.rs
are the entry points to the crate and define the root module. Other modules are nested under this and may exist in a file that matches the modules path in the tree. So a module atcrate::foo::bar::baz
can live in eitherfoo/bar/baz.rs
orfoo/bar/baz/mod.rs
. Or be defined as a inline module in the parent module (which may also be defined inline in its parent).This also means if you know the file path you know where it will exist in the tree,
a/b/c/d.rs
will be at the crate patha::b::c::d
.Yes, I like your explanations and I agree that's the way to think about it. But either way you have some special exceptions because
main.rs
maps tocrate
instead of tocrate::main
, anda/mod.rs
maps tocrate::a
instead of tocrate::a::mod
. I know that's the same thing you said, but I think it's worth emphasizing that the very first file you work with is one of the exceptions which makes it harder to see the general rule. It works just the way it should; but I sympathize with anyone getting started who hasn't internalized the special and general rules yet.