Example needs extern crate inline_python;

[glenn-horton-smith]

I found that the example given in the documentation and the README.md file would not compile with "cargo build" or "cargo run" unless I added the line extern crate inline_python; before the "use" statement. (I suspect this may be a hyphen thing.) Adding the line to the example in the docs.rs and github examples would save newcomers a little head scratching.

[m-ou-se]

Seems to work fine. Are you using an old Rust version or edition? This happens on edition 2015. On edition 2018, that extern crate statement is not needed.

[glenn-horton-smith]

I think I'm using a very recent nightly: "rustup show" tells me the active chain is using "rustc 1.46.0-nightly (346aec9b0 2020-07-11)".

$ rustup show
Default host: x86_64-unknown-linux-gnu
rustup home:  /home/gahs/.rustup

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu (default)

active toolchain
----------------

nightly-x86_64-unknown-linux-gnu (default)
rustc 1.46.0-nightly (346aec9b0 2020-07-11)

And rustc --version tells me the same thing.

I did another complete "rustup update" just in case, and there is no change. If I don't have the extern crate inline_python statement then I get

   Compiling inline_python_example v0.0.1 (/home/gahs/Documents/proglangs/rust/demo/inline_python_example)
error[E0432]: unresolved import `inline_python`
 --> src/bin/star.rs:2:5
  |
2 | use inline_python::{python};
  |     ^^^^^^^^^^^^^ maybe a missing crate `inline_python`?

What am I doing wrong?

[m-ou-se]

Sure, but are you using edition = "2018"? cargo new should;ve automatically put that in your Cargo.toml. If you don't have that there, you're using Rust 2015, which requires extern crate ...

[glenn-horton-smith]

Ah, stupid me! Thanks, that was the problem. Clearly I need to learn to always start new things with cargo new rather than reusing an existing example. Now everything works without extern crate. Closing this.

By the way, I seem to have discovered by accident that it is not necessary (with the latest nightly) to have

#![feature(proc_macro_hygiene)]

Perhaps that's not a stable thing, but it is interesting.

Thanks for the help and thanks for inline-python!

[m-ou-se]

Yes, that got into stable today, just a few hours ago. :) We'll be updating our crates soon.