return() inside eval

[A.J.]

This works as needed:

#!/usr/local/bin/perl
use strict;
use Exception::Class( 'Exception' );

sub test() {
eval {
return( param1 => 'first',
param2 => 'second' );
};
#print "here\n";
}

my %ret = &test();
print "param1:".$ret{param1}."\n";
print "param2:".$ret{param2}."\n";

>./test.pl

param1:first
param2:second

This doesn't. Why doesn't return work
properly in this case. Why is the print
clause executed? perl5.8.0
#!/usr/local/bin/perl
use strict;
use Exception::Class( 'Exception' );

sub test() {
eval {
return( param1 => 'first',
param2 => 'second' );
};
print "here\n";
}

my %ret = &test();
print "param1:".$ret{param1}."\n";
print "param2:".$ret{param2}."\n";

>./test.pl

here
param1:
param2:

[Stefan]

Using return within your eval returns from the eval block, not the
surrounding subroutine. The reason the first version works is that the
eval is the last statement, and therefore it's value is used as the
return value. In the first version you are returning eval which in turn
returns your hash. In the second version you are running eval, ignoring
the result and returning print.

Stefan


A.J. wrote:

> This works as needed:
>
> #!/usr/local/bin/perl
> use strict;
> use Exception::Class( 'Exception' );
>
> sub test() {
> eval {
> return( param1 => 'first',
> param2 => 'second' );
> };
> #print "here\n";
> }
>
> my %ret = &test();
> print "param1:".$ret{param1}."\n";
> print "param2:".$ret{param2}."\n";
>
>

>>./test.pl

>
> param1:first
> param2:second
>
> This doesn't. Why doesn't return work
> properly in this case. Why is the print
> clause executed? perl5.8.0
> #!/usr/local/bin/perl
> use strict;
> use Exception::Class( 'Exception' );
>
> sub test() {
> eval {
> return( param1 => 'first',
> param2 => 'second' );
> };
> print "here\n";
> }
>
> my %ret = &test();
> print "param1:".$ret{param1}."\n";
> print "param2:".$ret{param2}."\n";
>
>

>>./test.pl

>
> here
> param1:
> param2:
>
>
>

[A.J.]

The reason I want to use eval is to catch
possible exceptions inside various subroutines.
I'm using Exception::Class. Is there a better
way of doing this?

sub test() {
eval {
do something..

return( param1 => 'first',
param2 => 'second' );
};
if( UNIVERSAL::isa( $@, 'Exception' ) ) {
return( param1 => 'Catched exception:'.$@->message,
param2 => '' );
}
}

[Stefan]

A.J. wrote:

> The reason I want to use eval is to catch
> possible exceptions inside various subroutines.
> I'm using Exception::Class. Is there a better
> way of doing this?

Sure, just make sure you put your result in a variable before returning
it. For example:

sub test() {
my %result;
eval {
do something...
%result = (
param1 => 'first',...
);
}
if ($@) {
...
}
else {
return %result;
}
}