bjoernager/rust
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hack to make example compile

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Alex Burka 2016-06-14 15:53:55 -04:00 • committed by Alex Burka
parent 5276b29670
commit 54ecc210ec
1 changed files with 5 additions and 1 deletions
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6
src/doc/book/ffi.md
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@ -598,17 +598,21 @@ we have function pointers flying across the FFI boundary in both directions.
```rust ```rust
use std::os::raw::c_int; use std::os::raw::c_int;
# #[cfg(hidden)]
extern "C" { extern "C" {
/// Register the callback. /// Register the callback.
fn register(cb: Option<extern "C" fn(Option<extern "C" fn(c_int) -> c_int>, c_int) -> c_int>); fn register(cb: Option<extern "C" fn(Option<extern "C" fn(c_int) -> c_int>, c_int) -> c_int>);
} }
# unsafe fn register(_: Option<extern "C" fn(Option<extern "C" fn(c_int) -> c_int>,
# c_int) -> c_int>)
# {}
/// This fairly useless function receives a function pointer and an integer /// This fairly useless function receives a function pointer and an integer
/// from C, and returns the result of calling the function with the integer. /// from C, and returns the result of calling the function with the integer.
/// In case no function is provided, it squares the integer by default. /// In case no function is provided, it squares the integer by default.
extern "C" fn apply(process: Option<extern "C" fn(c_int) -> c_int>, int: c_int) -> c_int { extern "C" fn apply(process: Option<extern "C" fn(c_int) -> c_int>, int: c_int) -> c_int {
match process { match process {
Some(f) => unsafe { f(int) }, Some(f) => f(int),
None => int * int None => int * int
} }
} }