Crate cfg_if

Expand description

A macro for defining #[cfg] if-else statements.

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The macro provided by this crate, cfg_if, is similar to the if/elif C -preprocessor macro by allowing definition of a cascade of #[cfg] cases, -emitting the implementation which matches first.

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This allows you to conveniently provide a long list #[cfg]’d blocks of code -without having to rewrite each clause multiple times.

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Example

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cfg_if::cfg_if! {
-    if #[cfg(unix)] {
-        fn foo() { /* unix specific functionality */ }
-    } else if #[cfg(target_pointer_width = "32")] {
-        fn foo() { /* non-unix, 32-bit functionality */ }
-    } else {
-        fn foo() { /* fallback implementation */ }
-    }
-}
-

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Macros

cfg_if

The main macro provided by this crate. See crate documentation for more -information.