Feature request: Scope macros in prelude

[mehcode]

Using the Rust 2018 preview mode in nightly I find myself wanting to just import all the log macros in one go vs. having to name them explicitly.

// Current situation
use log::{log, info, error};

// Desired situation (only imports log macros)
use log::prelude::*;

[sanmai-NL]

The practice of using globs to specify items does not leave you with less cognitive load as author, but does add cognitive load for readers not yet familiar with the full set of log macros.

[tkilbourn]

I just ran into this, converting a medium-sized crate with lots of modules. use log::macros::*; would be acceptable to me as well, to call out that it's just the macros being imported.

[cavedweller]

I would also really like to have the macros namespaced so I could glob import them. This is not something I would expect to confuse people.

[alexcrichton]

The intention for the log crate in the near future is likely to take advantage of #[macro_export(local_inner_macros)] which won't need either a prelude module or a global import, and instead use log::info should work as expected.

[cavedweller]

@alexcrichton I think the comment here is that frequently we would frequently find ourselves with

use log::{warn, info, error}, when actually all I want to do is use log::*, then I frequently find myself being disrupted from my workflow when I need to go add another log level (since I didn't import them all because of deny(warnings).

I added syslog::macros::* for the Fuchsia syslog crate, and it works nicely.

[alexcrichton]

Ah ok, thanks for clarifying! Seems like a reasonable feature request to me!

[sanmai-NL]

@cavedweller and others reading that: a better way is to import all macros you ‘may’ use and allow unused imports on that import statement.

[cavedweller]

@sanmai-NL I think I disagree, for better or for worse, allows are significantly more confusing for a person onboarding to a codebase. They need to figure out what is special about that specific import, and then the statement doesn't get cleaned up when all the macros are actually all in use.

I don't think something like the import of logging utilities should take two lines either.

[sanmai-NL]

Any static analysis policy exception should of course be documented in a comment. Not cleaning the exception up would be proper in your case, it still applies, just happens to be inapplicable at some time, but could become applicable after a few changes. If you care about this then I’d suggest to just import what you use and change imports as necessary.

Complaining about the number of lines taken to achieve something (3 lines vs 1) is the kind of attitude that triggers me to put out this criticism. The job of a programmer is to produce quality software not type as little as possible (even though most of it is copy-paste, boilerplate stuff).