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.) ===