module Printexc:Facilities for printing exceptions.
val to_string :
exn -> string
Printexc.to_string ereturns a string representation of the exception
val print :
('a -> 'b) -> 'a -> 'b
Printexc.print fn xapplies
xand returns the result. If the evaluation of
fn xraises 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 xis 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.catchdoes. Moreover, calling
Printexc.catchmakes it harder to track the location of the exception using the debugger or the stack backtrace facility. So, do not use
Printexc.catchin new code.
val print_backtrace :
out_channel -> unit
Printexc.print_backtrace ocprints 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.
val get_backtrace :
unit -> string
Printexc.get_backtrace ()returns a string containing the same exception backtrace that
val record_backtrace :
bool -> unit
Printexc.record_backtrace bturns recording of exception backtraces on (if
b = true) or off (if
b = false). Initially, backtraces are not recorded, unless the
bflag is given to the program through the
val backtrace_status :
unit -> bool
trueif exception backtraces are currently recorded,
val register_printer :
(exn -> string option) -> unit
fnas an exception printer. The printer should return
Noneor raise an exception if it does not know how to convert the passed exception, and
sthe 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
Some s value (if no such printer exists, the runtime will use a
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.