Extended maintenance of Ruby 1.9.3 ended on February 23, 2015. Read more

In Files

  • fiddle/closure.c
  • fiddle/lib/fiddle/closure.rb



Class/Module Index [+]




An FFI closure wrapper, for handling callbacks.


closure = Class.new(Fiddle::Closure) {
  def call
}.new(Fiddle::TYPE_INT, [])
=> #<#<Class:0x0000000150d308>:0x0000000150d240>
func = Fiddle::Function.new(closure, [], Fiddle::TYPE_INT)
=> #<Fiddle::Function:0x00000001516e58>
=> 10



arguments of the FFI closure


the C type of the return of the FFI closure

Public Class Methods

new(ret, args, abi = Fiddle::DEFAULT) click to toggle source

Construct a new Closure object.

  • ret is the C type to be returned

  • args are passed the callback

  • abi is the abi of the closure

If there is an error in preparing the ffi_cif or ffi_prep_closure, then a RuntimeError will be raised.

               static VALUE
initialize(int rbargc, VALUE argv[], VALUE self)
    VALUE ret;
    VALUE args;
    VALUE abi;
    fiddle_closure * cl;
    ffi_cif * cif;
    ffi_closure *pcl;
    ffi_status result;
    int i, argc;

    if (2 == rb_scan_args(rbargc, argv, "21", &ret, &args, &abi))
        abi = INT2NUM(FFI_DEFAULT_ABI);

    Check_Type(args, T_ARRAY);

    argc = RARRAY_LENINT(args);

    TypedData_Get_Struct(self, fiddle_closure, &closure_data_type, cl);

    cl->argv = (ffi_type **)xcalloc(argc + 1, sizeof(ffi_type *));

    for (i = 0; i < argc; i++) {
        int type = NUM2INT(RARRAY_PTR(args)[i]);
        cl->argv[i] = INT2FFI_TYPE(type);
    cl->argv[argc] = NULL;

    rb_iv_set(self, "@ctype", ret);
    rb_iv_set(self, "@args", args);

    cif = &cl->cif;
    pcl = cl->pcl;

    result = ffi_prep_cif(cif, NUM2INT(abi), argc,

    if (FFI_OK != result)
        rb_raise(rb_eRuntimeError, "error prepping CIF %d", result);

    result = ffi_prep_closure_loc(pcl, cif, callback,
                (void *)self, cl->code);
    result = ffi_prep_closure(pcl, cif, callback, (void *)self);
    cl->code = (void *)pcl;
    i = mprotect(pcl, sizeof(*pcl), PROT_READ | PROT_EXEC);
    if (i) {

    if (FFI_OK != result)
        rb_raise(rb_eRuntimeError, "error prepping closure %d", result);

    return self;

Public Instance Methods

to_i() click to toggle source

Returns the memory address for this closure

               static VALUE
to_i(VALUE self)
    fiddle_closure * cl;
    void *code;

    TypedData_Get_Struct(self, fiddle_closure, &closure_data_type, cl);

    code = cl->code;

    return PTR2NUM(code);

Commenting is here to help enhance the documentation. For example, code samples, or clarification of the documentation.

If you have questions about Ruby or the documentation, please post to one of the Ruby mailing lists. You will get better, faster, help that way.

If you wish to post a correction of the docs, please do so, but also file bug report so that it can be corrected for the next release. Thank you.

If you want to help improve the Ruby documentation, please visit Documenting-ruby.org.