Macro ffi_dispatch

macro_rules! ffi_dispatch {
    (feature=$feature: expr, $handle: expr, $func: ident, $($arg: expr),*) => { ... };
    ($handle: expr, $func: ident, $($arg: expr),*) => { ... };
}

Macro for generically invoking a FFI function

The expected arguments are, in order:

• (Optional) The name of the cargo feature conditioning the usage of dlopen, in the form feature="feature-name". If ommited, the feature "dlopen" will be used.
• A value of the handle generated by the macro external_library! when the dlopen-controlling feature is enabled
• The name of the function to invoke
• The arguments to be passed to the function

The macro invocation evaluates to the return value of the FFI function.

Example

Assuming an FFI function of signature fn(u32, u32) -> u32:

let sum = unsafe { ffi_dispatch!(feature="dlopen", LIBRARY_HANDLE, sum, 2, 2) };