Cargo Features

shelfie has no features set by default.

[dependencies]
shelfie = { version = "1.0.1", features = ["logging"] }
logging = env_logger, log

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

log logging?
env_logger logging?

Enables env_logger ^0.10