Crate cfg_if

Expand description

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

+

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.

+

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

+

Example

+

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 */ }
+    }
+}
+

+

Macros

cfg_if

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