---
name: "Future::Exception"
section: "3pm"
platform: "linux"
package: "libfuture-perl"
version: "0.51-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Future::Exception"
---

# Future::Exception(3pm)

an exception type for failed Futures

## NAME

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

## SYNOPSIS

```
   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";
      }
   }
```

## DESCRIPTION

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.

## CONSTRUCTOR

### from\_future

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

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

## ACCESSORS

```
   $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.

## METHODS

### throw

```
   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.

### as\_future

```
   $f = $e->as_future;
```

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

## AUTHOR

Paul Evans \<leonerd@leonerd.org.uk\>