# Module Batteries.Printexc

    module Printexc: BatPrintexc

    val pass : ('a -> 'b) -> 'a -> 'b

`Printexc.pass 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 function application. This function is a renamed version of `Printexc.print` from stdlib.

    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 to_string : exn -> string

`Printexc.to_string e` returns a string representation of the exception `e`.

    val print_backtrace : 'a BatInnerIO.output -> unit

`print_backtrace oc` Prints the 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 1.4.0

    val get_backtrace : unit -> string

`Printexc.get_backtrace ()` returns a string containing the same exception backtrace that `Printexc.print_backtrace` would print.

    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.

    val backtrace_status : unit -> bool

`Printexc.backtrace_status()` returns `true` if exception backtraces are currently recorded, `false` if not.

    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).

    val print : 'a BatInnerIO.output -> exn -> unit

Print an exception. The stdlib `print` function is now named `!pass`.