comment on

I have another custom approach:

sub new {
    my ($thing) = @_ ;
    
    my $class = ( ref($thing) or $thing ) ;
    my $self = bless({}, $class) ;
    
    $self->{'errMsg'} = "";

    # module user can set this e.g. to sub { carp($_[0]->{'errMsg'}) }
+ or something:
    $self->{'errHandler'};

    return $self ;
}

# Sets an error message, calls the error Handler, always returns undef
sub raiseError {
    my ($self, $string) = @_;
    $self->{'errMsg'} = $string;
    &{$self->{'errHandler'}}($self) if $self->{'errHandler'};
    return;
}

# returns error message and resets it to ""
sub error {
    my ($self) = @_;
    
    my $msg = $self->{'errMsg'};
    $self->{'errMsg'} = "";
    return $msg;
}


# ...

sub foo {
    my ($self) = @_;
    # do stuff
    if ($trouble) {
        return raiseError("foo: cannot do thisandthat");
    }
    # no error:
    # make sure to return true-evaluating or at least non-undef value
    return 1;
}
[download]

This way the module user can still use idioms like

$O->foo() or die "could not blabla: ".$O->error();
[download]

Users can still set the error handler to croak() if they wish. This could be extended ad nauseam: $debug switches, $exec_handler switch, method to get errMsg without resetting it -- you name it. I should probably put it in its own module, too, and inherit from that. I'm still not sure how to escalate errors when one method calls another. Maybe simply

sub bar {
    my ($self) = @_;

    foo() or return raiseError("bar failed to rhubarb: ".$self->error(
+));
    return 1;
}

# ...

$O->bar() or die "could not blabla: ".$O->error();
# "could not blabla: bar failed to rhubarb: foo: could not do thisandt
+hat"
[download]

In reply to Re^3: Error Handling with Packages by anjoschu
in thread Error Handling with Packages by Dru

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