.TH "Callback" 3o 2023-09-18 OCamldoc "OCaml library"
.SH NAME
Callback \- Registering OCaml values with the C runtime.
.SH Module
Module   Callback
.SH Documentation
.sp
Module
.BI "Callback"
 : 
.B sig end

.sp
Registering OCaml values with the C runtime\&.
.sp
This module allows OCaml values to be registered with the C runtime
under a symbolic name, so that C code can later call back registered
OCaml functions, or raise registered OCaml exceptions\&.

.sp

.sp
.sp

.I val register 
: 
.B string -> 'a -> unit
.sp

.ft B
Callback\&.register n v
.ft R
registers the value 
.ft B
v
.ft R
under
the name 
.ft B
n
.ft R
\&. C code can later retrieve a handle to 
.ft B
v
.ft R
by calling 
.ft B
caml_named_value(n)
.ft R
\&.

.sp

.I val register_exception 
: 
.B string -> exn -> unit
.sp

.ft B
Callback\&.register_exception n exn
.ft R
registers the
exception contained in the exception value 
.ft B
exn
.ft R
under the name 
.ft B
n
.ft R
\&. C code can later retrieve a handle to
the exception by calling 
.ft B
caml_named_value(n)
.ft R
\&. The exception
value thus obtained is suitable for passing as first argument
to 
.ft B
raise_constant
.ft R
or 
.ft B
raise_with_arg
.ft R
\&.

.sp