check_gl Rust macro

check_gl.rs

// example usage:
//
// check_gl!(glVertexAttribPointer(attrib, 4, GL_FLOAT, GL_FALSE as GLboolean, 0, null()));
//
// if there is an error it outputs: `OpenGL <<opengl error code>>: <<function identifier>>(<<function arguments>>)`
//


#[cfg(check_gl)]
macro_rules! check_gl (
    ($fun:ident ($($arg:expr),*)) => (
        util::check_gl_callback(
            move $fun ( $($arg),* ), stringify!($fun ( $($arg),* ) )
        )
    )
)

// Not currently possible - this is a skeleton macro that when expanded should not impact performance at runtime
// #[cfg(!check_gl)]
// macro_rules! check_gl (
//     ($fun:ident ($($arg:expr),*)) => ( $fun ( $($arg),* ) )
// )

fn check_gl_callback<T>(v: T, fn_string: &str) -> T {
    let err = glGetError();
    if err != GL_NO_ERROR {
        io::println(fmt!("OpenGL %s: %s", gl_error_string(err), connect(words(fn_string), " ")));
    }
    return move v;
}