Scroll to navigation

Future::Exception(3pm) User Contributed Perl Documentation Future::Exception(3pm)


"Future::Exception" - an exception type for failed Futures


   use Scalar::Util qw( blessed );
   use Syntax::Keyword::Try;
   try {
      my $f = ...;
      my @result = $f->result;
   catch {
      if( blessed($@) and $@->isa( "Future::Exception" ) {
         print STDERR "The ", $@->category, " failed: ", $@->message, "\n";


The "get" method on a failed Future instance will throw an exception to indicate that the future failed. A failed future can contain a failure category name and other details as well as the failure message, so in this case the exception will be an instance of "Future::Exception" to make these values accessible.

Users should not depend on exact class name matches, but instead rely on inheritence, as a later version of this implementation might dynamically create subclasses whose names are derived from the Future failure category string, to assist with type matching. Note the use of "->isa" in the SYNOPSIS example.



   $e = Future::Exception->from_future( $f )

Constructs a new "Future::Exception" wrapping the given failed future.


   $message  = $e->message
   $category = $e->category
   @details  = $e->details

Additionally, the object will stringify to return the message value, for the common use-case of printing, regexp testing, or other behaviours.



   Future::Exception->throw( $message, $category, @details )

Since version 0.41.

Constructs a new exception object and throws it using "die()". This method will not return, as it raises the exception directly.

If $message does not end in a linefeed then the calling file and line number are appended to it, in the same way "die()" does.


   $f = $e->as_future

Returns a new "Future" object in a failed state matching the exception.


Paul Evans <>

2023-06-11 perl v5.36.0