autodie::exception

NAME

SYNOPSIS

    eval {
        use autodie;

        open(my $fh, '<', 'some_file.txt');

        ...
    };

    if (my $E = $@) {
        say "Ooops!  ",$E->caller," had problems: $@";
    }

DESCRIPTION

This document is broken into two sections; those methods that are most useful to the end-developer, and those methods for anyone wishing to subclass or get very familiar with "autodie::exception".  

Common Methods

The following assume that the error has been copied into a separate scalar:

    if ($E = $@) {
        ...
    }

This is not required, but is recommended in case any code is called which may reset or alter $@.

args

    my $array_ref = $E->args;

Provides a reference to the arguments passed to the subroutine that died.

function

    my $sub = $E->function;

The subroutine (including package) that threw the exception.

file

    my $file = $E->file;

The file in which the error occurred (eg, "myscript.pl" or "MyTest.pm").

package

    my $package = $E->package;

The package from which the exceptional subroutine was called.

caller

    my $caller = $E->caller;

The subroutine that called the exceptional code.

line

    my $line = $E->line;

The line in "$E->file" where the exceptional code was called.

errno

    my $errno = $E->errno;

The value of $! at the time when the exception occurred.

NOTE: This method will leave the main "autodie::exception" class and become part of a role in the future. You should only call "errno" for exceptions where $! would reasonably have been set on failure.

matches

    if ( $e->matches('open') ) { ... }

    if ( $e ~~ 'open' ) { ... }

"matches" is used to determine whether a given exception matches a particular role. On Perl 5.10, using smart-match ("~~") with an "autodie::exception" object will use "matches" underneath.

An exception is considered to match a string if:

*

For a string not starting with a colon, the string exactly matches the package and subroutine that threw the exception. For example, "MyModule::log". If the string does not contain a package name, "CORE::" is assumed.

*

For a string that does start with a colon, if the subroutine throwing the exception does that behaviour. For example, the "CORE::open" subroutine does ":file", ":io" and ":all".

See ``CATEGORIES'' in autodie for futher information.

Advanced methods

register

    autodie::exception->register( 'CORE::open' => \&mysub );

The "register" method allows for the registration of a message handler for a given subroutine. The full subroutine name including the package should be used.

Registered message handlers will receive the "autodie::exception" object as the first parameter.

add_file_and_line

    say "Problem occurred",$@->add_file_and_line;

Returns the string " at %s line %d", where %s is replaced with the filename, and %d is replaced with the line number.

Primarily intended for use by format handlers.

stringify

    say "The error was: ",$@->stringify;

Formats the error as a human readable string. Usually there's no reason to call this directly, as it is used automatically if an "autodie::exception" object is ever used as a string.

Child classes can override this method to change how they're stringified.

format_default

    my $error_string = $E->format_default;

This produces the default error string for the given exception, without using any registered message handlers. It is primarily intended to be called from a message handler when they have been passed an exception they don't want to format.

Child classes can override this method to change how default messages are formatted.

new

    my $error = autodie::exception->new(
        args => \@_,
        function => "CORE::open",
        errno => $!,
    );

Creates a new "autodie::exception" object. Normally called directly from an autodying function. The "function" argument is required, its the function we were trying to call that generated the exception. The "args" parameter is optional.

The "errno" value is optional. In versions of "autodie::exception" 1.99 and earlier the code would try to automatically use the current value of $!, but this was unreliable and is no longer supported.

Atrributes such as package, file, and caller are determined automatically, and cannot be specified.  

SEE ALSO

LICENSE

This is free software. You may modify and/or redistribute this code under the same terms as Perl 5.10 itself, or, at your option, any later version of Perl 5.  

AUTHOR