Callback(3) OCaml library Callback(3)NAME
Callback - Registering OCaml values with the C runtime.
Module
Module Callback
Documentation
Module Callback
: sig end
Registering OCaml values with the C runtime.
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.
val register : string -> 'a -> unit
Callback.register n v registers the value v under the name n . C code can later retrieve a handle to v by calling caml_named_value(n) .
val register_exception : string -> exn -> unit
Callback.register_exception n exn registers the exception contained in the exception value exn under the name n . C code can later retrieve
a handle to the exception by calling caml_named_value(n) . The exception value thus obtained is suitable for passing as first argument to
raise_constant or raise_with_arg .
OCamldoc 2014-06-09 Callback(3)
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Printexc(3) OCaml library Printexc(3)NAME
Printexc - Facilities for printing exceptions.
Module
Module Printexc
Documentation
Module Printexc
: sig end
Facilities for printing exceptions.
val to_string : exn -> string
Printexc.to_string e returns a string representation of the exception e .
val print : ('a -> 'b) -> 'a -> 'b
Printexc.print fn x applies fn to x and returns the result. If the evaluation of fn x raises any exception, the name of the exception is
printed on standard error output, and the exception is raised again. The typical use is to catch and report exceptions that escape a func-
tion application.
val catch : ('a -> 'b) -> 'a -> 'b
Printexc.catch fn x is similar to Printexc.print , but aborts the program with exit code 2 after printing the uncaught exception. This
function is deprecated: the runtime system is now able to print uncaught exceptions as precisely as Printexc.catch does. Moreover, calling
Printexc.catch makes it harder to track the location of the exception using the debugger or the stack backtrace facility. So, do not use
Printexc.catch in new code.
val print_backtrace : Pervasives.out_channel -> unit
Printexc.print_backtrace oc prints an exception backtrace on the output channel oc . The backtrace lists the program locations where the
most-recently raised exception was raised and where it was propagated through function calls.
Since 3.11.0
val get_backtrace : unit -> string
Printexc.get_backtrace () returns a string containing the same exception backtrace that Printexc.print_backtrace would print.
Since 3.11.0
val record_backtrace : bool -> unit
Printexc.record_backtrace b turns recording of exception backtraces on (if b = true ) or off (if b = false ). Initially, backtraces are
not recorded, unless the b flag is given to the program through the OCAMLRUNPARAM variable.
Since 3.11.0
val backtrace_status : unit -> bool
Printexc.backtrace_status() returns true if exception backtraces are currently recorded, false if not.
Since 3.11.0
val register_printer : (exn -> string option) -> unit
Printexc.register_printer fn registers fn as an exception printer. The printer should return None or raise an exception if it does not
know how to convert the passed exception, and Some s with s the resulting string if it can convert the passed exception. Exceptions raised
by the printer are ignored.
When converting an exception into a string, the printers will be invoked in the reverse order of their registrations, until a printer
returns a Some s value (if no such printer exists, the runtime will use a generic printer).
When using this mechanism, one should be aware that an exception backtrace is attached to the thread that saw it raised, rather than to the
exception itself. Practically, it means that the code related to fn should not use the backtrace if it has itself raised an exception
before.
Since 3.11.2
OCamldoc 2014-06-09 Printexc(3)