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aa548f4431
Reverts google/comprehensive-rust#2383 Since #2397 is merged, to align the goal in #2478, rollback this temp workaround.
27 lines
846 B
Markdown
27 lines
846 B
Markdown
---
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minutes: 20
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---
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# Exercise: Logger Trait
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Let's design a simple logging utility, using a trait `Logger` with a `log`
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method. Code which might log its progress can then take an `&impl Logger`. In
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testing, this might put messages in the test logfile, while in a production
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build it would send messages to a log server.
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However, the `StderrLogger` given below logs all messages, regardless of
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verbosity. Your task is to write a `VerbosityFilter` type that will ignore
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messages above a maximum verbosity.
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This is a common pattern: a struct wrapping a trait implementation and
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implementing that same trait, adding behavior in the process. What other kinds
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of wrappers might be useful in a logging utility?
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```rust,compile_fail
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{{#include exercise.rs:setup}}
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// TODO: Define and implement `VerbosityFilter`.
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{{#include exercise.rs:main}}
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```
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