NAME

       Printexc - Facilities for printing exceptions and inspecting current call stack.

Module

       Module   Printexc

Documentation

       Module Printexc
        : sig end

       Facilities for printing exceptions and inspecting current call stack.

       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 function 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

       === Raw backtraces ===

       type raw_backtrace

       === The abstract type backtrace stores exception backtraces in a low-level format, instead
       of  directly  exposing  them  as string as the get_backtrace() function does.  This allows
       delaying the formatting of backtraces to when they are actually printed,  which  might  be
       useful if you record more backtraces than you print. ===

       val get_raw_backtrace : unit -> raw_backtrace

       val print_raw_backtrace : Pervasives.out_channel -> raw_backtrace -> unit

       val raw_backtrace_to_string : raw_backtrace -> string

       === Current call stack ===

       val get_callstack : int -> raw_backtrace

       ===  Printexc.get_callstack  n  returns  a description of the top of the call stack on the
       current program point (for the current thread),  with  at  most  n  entries.  (Note:  this
       function  is not related to exceptions at all, despite being part of the Printexc module.)
       ===