Getting croak or carp into variable ?

[Dan Muey]

Hello List,

I am using a module that does use Carp; and you
can specify whther you want croak or carp on an error
Which is cool. But there is no way to specify anythign
else besides those two.

So the way it is you just do:

my $res = funktion('foobarmonkey',err_doer => 'carp');

And it will do
carp('what the heck is foobarmonkey');

What I'd like to do is get any errors into a variable:

my $err = '';
my $res = funktion('foobarmonkey',err_doer => 'puterrorinvar');

if($err) {
print "Error: $err\n";
print "Logging error..."'
if(logerror($err) { print "Ok\n"; } else { print "Failed!\n"; }
print "Emailing Admin...";
if(emailadmin($err)) { print "Ok\n"; } else { print "Failed!\n"; }
# and now that we did that we can go ahead and carp, craok die, whatever
}

Except I can't simply specify a new function for errors because it checks for what you enter to see if its in a hash and if not defaults to one or the other. (I could modify the module but then it won't work for all)

SO I guess the question is, is there a way to get carp or croak into a variable?
Something like this perhaps: ?

my $err = '';
putcarpinvar_on(\$err); # this is an example to illustrate what I'm shooting for it is not real
my $res = funktion('foobarmonkey',err_doer => 'puterrorinvar');
putcarpinvar_off(\$err); # this is an example to illustrate what I'm shooting for it is not real
if($err) { ...

Any ideas?

TIA

Dan

[James Edward Gray II]

On Feb 10, 2004, at 9:56 AM, Dan Muey wrote:

> Hello List,
>
> I am using a module that does use Carp; and you
> can specify whther you want croak or carp on an error
> Which is cool. But there is no way to specify anythign
> else besides those two.
>
> So the way it is you just do:
>
> my $res = funktion('foobarmonkey',err_doer => 'carp');
>
> And it will do
> carp('what the heck is foobarmonkey');
>
> What I'd like to do is get any errors into a variable:
>
> my $err = '';
> my $res = funktion('foobarmonkey',err_doer => 'puterrorinvar');
>
> if($err) {
> print "Error: $err\n";
> print "Logging error..."'
> if(logerror($err) { print "Ok\n"; } else { print "Failed!\n"; }
> print "Emailing Admin...";
> if(emailadmin($err)) { print "Ok\n"; } else { print "Failed!\n"; }
> # and now that we did that we can go ahead and carp, craok die,
> whatever
> }
>
> Except I can't simply specify a new function for errors because it
> checks for what you enter to see if its in a hash and if not defaults
> to one or the other. (I could modify the module but then it won't work
> for all)
>
> SO I guess the question is, is there a way to get carp or croak into a
> variable?
> Something like this perhaps: ?

Maybe. Check out this one liner:

perl -MCarp -e '$SIG{__WARN__} = sub { $err = shift; }; carp
"Error!\n"; print "We caught $err";'

Strangely though, this did not work for me, though I expected it to:

perl -MCarp -e '$SIG{__DIE__} = sub { $err = shift; }; croak
"Error!\n"; print "We caught $err";'

James

[Dan Muey]

> On Feb 10, 2004, at 9:56 AM, Dan Muey wrote:
>

> > Hello List,
> >
> > I am using a module that does use Carp; and you
> > can specify whther you want croak or carp on an error
> > Which is cool. But there is no way to specify anythign
> > else besides those two.
> >
> > So the way it is you just do:
> >
> > my $res = funktion('foobarmonkey',err_doer => 'carp');
> >
> > And it will do
> > carp('what the heck is foobarmonkey');
> >
> > What I'd like to do is get any errors into a variable:
> >
> > my $err = '';
> > my $res = funktion('foobarmonkey',err_doer => 'puterrorinvar');
> >
> > if($err) {
> > print "Error: $err\n";
> > print "Logging error..."'
> > if(logerror($err) { print "Ok\n"; } else { print "Failed!\n"; }
> > print "Emailing Admin...";
> > if(emailadmin($err)) { print "Ok\n"; } else { print

> "Failed!\n"; }

> > # and now that we did that we can go ahead and carp, craok die,
> > whatever
> > }
> >
> > Except I can't simply specify a new function for errors because it
> > checks for what you enter to see if its in a hash and if

> not defaults

> > to one or the other. (I could modify the module but then it

> won't work

> > for all)
> >
> > SO I guess the question is, is there a way to get carp or

> croak into a

> > variable?
> > Something like this perhaps: ?

>
> Maybe. Check out this one liner:
>
> perl -MCarp -e '$SIG{__WARN__} = sub { $err = shift; }; carp
> "Error!\n"; print "We caught $err";'
>
> Strangely though, this did not work for me, though I expected it to:
>
> perl -MCarp -e '$SIG{__DIE__} = sub { $err = shift; }; croak
> "Error!\n"; print "We caught $err";'

Oh yeah %SIG I've nvere really messed with it before.
I'll check it out a bit more, thanks James!

Dan

>
> James
>
>

[Dan Muey]

> perl -MCarp -e '$SIG{__WARN__} = sub { $err = shift; };

> carp "Error!\n"; print "We caught $err";'
>

This works great!

And changing $SIG{__WARN__} to '' will return default behaviour correct?
(Same thign with __DIE__ ??)

> Strangely though, this did not work for me, though I expected it to:
>
> perl -MCarp -e '$SIG{__DIE__} = sub { $err = shift; }; croak
> "Error!\n"; print "We caught $err";'
>

Anyone have any idea how to get $SIG{__DIE__} to act like the $SIG{__WARN__} ?
I'm sure it has something to do with die doing an exit() or soemthing.

> James

[Jeff 'Japhy' Pinyan]

On Feb 10, Dan Muey said:

>I am using a module that does use Carp; and you
>can specify whther you want croak or carp on an error
>Which is cool. But there is no way to specify anythign
>else besides those two.
>
>What I'd like to do is get any errors into a variable:

You want Carp::shortmess().

perldoc Carp

--
Jeff "japhy" Pinyan [email]japhy@pobox.com[/email] [url]http://www.pobox.com/~japhy/[/url]
RPI Acacia brother #734 [url]http://www.perlmonks.org/[/url] [url]http://www.cpan.org/[/url]
<stu> what does y/// stand for? <tenderpuss> why, yansliterate of course.
[ I'm looking for programming work. If you like my work, let me know. ]

[Wiggins D Anconia]

> Hello List,

>
> I am using a module that does use Carp; and you
> can specify whther you want croak or carp on an error
> Which is cool. But there is no way to specify anythign
> else besides those two.
>
> So the way it is you just do:
>
> my $res = funktion('foobarmonkey',err_doer => 'carp');
>
> And it will do
> carp('what the heck is foobarmonkey');
>
> What I'd like to do is get any errors into a variable:
>
> my $err = '';
> my $res = funktion('foobarmonkey',err_doer => 'puterrorinvar');
>
> if($err) {
> print "Error: $err\n";
> print "Logging error..."'
> if(logerror($err) { print "Ok\n"; } else { print "Failed!\n"; }
> print "Emailing Admin...";
> if(emailadmin($err)) { print "Ok\n"; } else { print "Failed!\n"; }
> # and now that we did that we can go ahead and carp, craok die, whatever
> }
>
> Except I can't simply specify a new function for errors because it

checks for what you enter to see if its in a hash and if not defaults to
one or the other. (I could modify the module but then it won't work for all)

>
> SO I guess the question is, is there a way to get carp or croak into a

variable?

> Something like this perhaps: ?
>
> my $err = '';
> putcarpinvar_on(\$err); # this is an example to illustrate what I'm

shooting for it is not real

> my $res = funktion('foobarmonkey',err_doer => 'puterrorinvar');
> putcarpinvar_off(\$err); # this is an example to illustrate what I'm

shooting for it is not real

> if($err) { ...
>
> Any ideas?
>

It appears you are talking about exceptions in a try/catch manner? You
may want to look at

perldoc -f die
perldoc -f eval

And see if the mess of docs there helps. It is pretty scattered at least
to me, but I think it will provide what you want. An example might be,

my $res = eval { call_function() };
if ($@) {
# $@ contains your variable's value
}

# else process $res here

This seems like it would simulate what you are after. Because croak is
just a replacement for 'die' it should work the same way giving you the
same benefits. It is really the 'eval' that is the significant part of
the construct despite it being explained in the 'die' docs...

I have a cursory understanding of standard exception models, and have
built my own version for Perl modules that doesn't quite fit into the
above (yet!), but reading the Learning Python book has helped solidify
my understanding and suggesting the changes I need to make to my own
implementation.

Thoughts?

[url]http://danconia.org[/url]

[Dan Muey]

> >I am using a module that does use Carp; and you
> >can specify whther you want croak or carp on an error
> >Which is cool. But there is no way to specify anythign
> >else besides those two.
> >
> >What I'd like to do is get any errors into a variable:

>
> You want Carp::shortmess().
>
> perldoc Carp

That would require modifying the module which I want to avoid.
Inside a function of another package it calls either carp or croak.
I'd like to get that error into a variable I can use and not die
or warn from croak or carp.

my $err = '';
$SIG{__WARN__} = sub { $err = shift; }
$SIG{__DIE__} = sub {$err = shift; }

my $res = function_that_carps_or_croaks_that_i_cant_modify() ;
if($err) { handle_error_my_way_instead_of_simply_carping_or_c roaking($err); }

$SIG{__WARN__} = ''; # or is undef or delete better??
$SIG{__DIE__} = ''; # or is undef or delete better??

That works like a charm but it does not work with $SIG{__DIE__} for some reason.
It still just croaks as usual. Any ideas?

>
> --
> Jeff "japhy" Pinyan [email]japhy@pobox.com[/email]

[Dan Muey]

> Dan Muey wrote:

>
> [snip]
>

> > $SIG{__WARN__} = ''; # or is undef or delete better??

> $SIG{__DIE__} =

> > ''; # or is undef or delete better??
> >
> > That works like a charm but it does not work with $SIG{__DIE__} for
> > some reason. It still just croaks as usual. Any ideas?
> >

>
> there are at least a couple of ways of doing that:
>
> #!/usr/bin/perl -w
> use strict;
>
> BEGIN{
> use subs qw(Carp::die);
> use vars qw($e);
> sub Carp::die{ $e = "Carp::die: @_" }
> }
>
> use Carp;
>
> croak "croaking";
>
> print "after croak \$e is: $e";
>
> __END__
>
> prints:
>
> after croak $e is: Carp::die: croaking at x.pl line 10
>
> another way to accomplish the same thing:
>
> #!/usr/bin/perl -w
> use strict;
>
> BEGIN{
>
> our $e;
>
> *CORE::GLOBAL::die = sub{
> $e = "CORE:GLOBAL::die => @_";
> };
> }
>
> use Carp;
>
> use vars qw($e);
>
> croak "croaking";
>
> print "after croak \$e is: $e";
>
> __END__
>
> prints:
>
> after croak $e is: CORE:GLOBAL::die => croaking at x.pl line 10
>
> i don't have time to check out the source of Carp.pm but if
> you do, i would
> suggest you go take a look as there might be a better
> solution to it. out
> of the 2 methods i described, the second one is more natural, imo.
>

Cool, I was wondering about if that was possible, overriding the function.
I'll try that out a bit and see how iut can fit into my scheme.

Thanks david!

> david

[David]

Dan Muey wrote:

[snip]

> $SIG{__WARN__} = ''; # or is undef or delete better??
> $SIG{__DIE__} = ''; # or is undef or delete better??
>
> That works like a charm but it does not work with $SIG{__DIE__} for some
> reason. It still just croaks as usual. Any ideas?
>

there are at least a couple of ways of doing that:

#!/usr/bin/perl -w
use strict;

BEGIN{
use subs qw(Carp::die);
use vars qw($e);
sub Carp::die{ $e = "Carp::die: @_" }
}

use Carp;

croak "croaking";

print "after croak \$e is: $e";

__END__

prints:

after croak $e is: Carp::die: croaking at x.pl line 10

another way to accomplish the same thing:

#!/usr/bin/perl -w
use strict;

BEGIN{

our $e;

*CORE::GLOBAL::die = sub{
$e = "CORE:GLOBAL::die => @_";
};
}

use Carp;

use vars qw($e);

croak "croaking";

print "after croak \$e is: $e";

__END__

prints:

after croak $e is: CORE:GLOBAL::die => croaking at x.pl line 10

i don't have time to check out the source of Carp.pm but if you do, i would
suggest you go take a look as there might be a better solution to it. out
of the 2 methods i described, the second one is more natural, imo.

david
--
sub'_{print"@_ ";* \ = * __ ,\ & \}
sub'__{print"@_ ";* \ = * ___ ,\ & \}
sub'___{print"@_ ";* \ = * ____ ,\ & \}
sub'____{print"@_,\n"}&{_+Just}(another)->(Perl)->(Hacker)

[James Edward Gray II]

On Feb 10, 2004, at 11:53 AM, Dan Muey wrote:

>> perl -MCarp -e '$SIG{__WARN__} = sub { $err = shift; };
>> carp "Error!\n"; print "We caught $err";'
>>

>
> This works great!
>
> And changing $SIG{__WARN__} to '' will return default behaviour
> correct?
> (Same thign with __DIE__ ??)

Just undef them:

undef $SIG{__WARN__};

>> Strangely though, this did not work for me, though I expected it to:
>>
>> perl -MCarp -e '$SIG{__DIE__} = sub { $err = shift; }; croak
>> "Error!\n"; print "We caught $err";'
>>

>
> Anyone have any idea how to get $SIG{__DIE__} to act like the
> $SIG{__WARN__} ?
> I'm sure it has something to do with die doing an exit() or soemthing.

This was my misunderstanding. I looked back over the __DIE__ handler.
It gets called on the way down, it doesn't override the fact that you
are going down. My bad. Use __WARN__.

James

[Dan Muey]

> there are at least a couple of ways of doing that:

>
> #!/usr/bin/perl -w
> use strict;
>
> BEGIN{
> use subs qw(Carp::die);
> use vars qw($e);
> sub Carp::die{ $e = "Carp::die: @_" }
> }
>
> use Carp;
>
> croak "croaking";
>
> print "after croak \$e is: $e";
>
> __END__
>
> prints:
>
> after croak $e is: Carp::die: croaking at x.pl line 10
>
> another way to accomplish the same thing:
>
> #!/usr/bin/perl -w
> use strict;
>
> BEGIN{
>
> our $e;
>
> *CORE::GLOBAL::die = sub{
> $e = "CORE:GLOBAL::die => @_";
> };
> }
>
> use Carp;
>
> use vars qw($e);
>
> croak "croaking";
>
> print "after croak \$e is: $e";
>
> __END__
>
> prints:
>
> after croak $e is: CORE:GLOBAL::die => croaking at x.pl line 10
>
> i don't have time to check out the source of Carp.pm but if
> you do, i would
> suggest you go take a look as there might be a better
> solution to it. out
> of the 2 methods i described, the second one is more natural, imo.

Thanks that helped out abunch I believe it has me up and running!
I use the Carp::die so I won't effect any real die()s just the croak()s

Thanks again!

Dan