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Module Exn

Signature

include Core.Std.Exn
type t = exn

sexp_of_t uses a global table of sexp converters. To register a converter for a new exception, add [@@deriving sexp] to its definition. If no suitable converter is found, the standard converter in Printexc will be used to generate an atomic S-expression.

val sexp_of_t : t -> Sexplib.Sexp.t
include Core_kernel.Pretty_printer.S with type t := t
type t
val pp : Format.formatter -> t -> unit
exception Finally of t * t

Raised when finalization after an exception failed, too. The first exception argument is the one raised by the initial function, the second exception the one raised by the finalizer.

exception Reraised of string * t
val raise_without_backtrace : t -> _

Same as raise, except that the backtrace is not recorded.

val reraise : t -> string -> _
val reraisef : t -> ('a, unit, string, unit -> _) Pervasives.format4 -> 'a

Types with format4 are hard to read, so here's an example.


      let foobar str =
        try
          ...
        with exn ->
          Exn.reraisef exn "Foobar is buggy on: %s" str ()
val to_string : t -> string
val to_string_mach : t -> string
val protectx : f:('a -> 'b) -> 'a -> finally:('a -> unit) -> 'b

Executes f and afterwards executes finally, whether f throws an exception or not.

val protect : f:(unit -> 'a) -> finally:(unit -> unit) -> 'a
val handle_uncaught : exit:bool -> (unit -> unit) -> unit

handle_uncaught ~exit f catches an exception escaping f and prints an error message to stderr. Exits with return code 1 if exit is true. Otherwise returns unit.

Note that since OCaml 4.02.0, it is not needed to use this at the entry point of your program as the OCaml runtime will do better than this function.

val handle_uncaught_and_exit : (unit -> 'a) -> 'a

handle_uncaught_and_exit f returns f (), unless that raises, in which case it prints the exception and exits nonzero.

val reraise_uncaught : string -> (unit -> 'a) -> 'a

Traces exceptions passing through. Useful because in practice backtraces still don't seem to work.

Example: 


    let rogue_function () = if Random.bool () then failwith "foo" else 3
    let traced_function () = Exn.reraise_uncaught "rogue_function" rogue_function
    traced_function ();;
    

 : Program died with Reraised("rogue_function", Failure "foo")
val does_raise : (unit -> _) -> bool

does_raise f returns true iff f () raises, which is often useful in unit tests.

val backtrace : unit -> string

The same as Printexc.get_backtrace

val initialize_module : unit -> unit

Runs global side effects, which change the display of exceptions and install an uncaught-exception printer.

include Extended_exn
val to_string : exn -> string

The to_string function is slightly tweaked to avoid escaping the string content of Failure.

val to_string_hum : exn -> string

This is also an ever so slight variation of to_string target more at user than developers (Failure s is just printed as s)

val unwrap : exn -> exn

unwrap e

Tries to unwrap an exception to find the original cause of the error (Finally for instance has the propency to burry exception...). This is useful when matching on exceptions.

module Exn_string : sig .. end
The point of this module is to be able to include an exn in a type that has to be sexpable or binable.