34 lines
1.0 KiB
Plaintext
34 lines
1.0 KiB
Plaintext
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---
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source: tests/output.rs
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expression: "get_stdout(&[item])"
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---
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anyhow Macro anyhow::ensure rusty-man
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SYNOPSIS
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macro_rules! ensure {
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($cond:expr, $msg:literal $(,)?) => { ... };
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($cond:expr, $err:expr $(,)?) => { ... };
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($cond:expr, $fmt:expr, $($arg:tt)*) => { ... };
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}
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DESCRIPTION
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Return early with an error if a condition is not satisfied.
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This macro is equivalent to `if !$cond { return Err(From::from($err)); }`.
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Analogously to `assert!`, `ensure!` takes a condition and exits the function if the condition
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fails. Unlike `assert!`, `ensure!` returns an `Error` rather than panicking.
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# Example
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ensure!(user == 0, "only user 0 is allowed");
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#[derive(Error, Debug)]
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enum ScienceError {
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#[error("recursion limit exceeded")]
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RecursionLimitExceeded,
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...
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}
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ensure!(depth <= MAX_DEPTH, ScienceError::RecursionLimitExceeded);
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