tame1 has asked for the wisdom of the Perl Monks concerning the following question:

I read the "my() troubles" post with interest( I would link it here, but I'm not sure how to do that), because something occured to me. Would/Could one use bless in that circumstance?

In other words, to make the variable available outside of the enclosed block, could you "bless $var, $subname" ?

I am just now studying up on things like bless (reading the Tie section of Prog. Perl, 3rd Ed.) and would love for someone to explain how (or how not) to use bless in this case.

What does this little button do . .<Click>; "USER HAS SIGNED OFF FOR THE DAY"

Replies are listed 'Best First'.
Re: Bless to use my'd $var outside of block?
by jeroenes (Priest) on Feb 14, 2001 at 20:31 UTC
    tame1 I'm sorry for you, but bless has nothing to do with the 'availability' of your variables. The issue here is scoping: what is the scope of the variables. You can declare variables global with use vars qw($var1 @var2); It's better to use my in other cases.

    In addition to working through Prog. Perl, I'd recommend to read some manpages:

    To just name a few. bless has to do with Object-Oriented Perl. So whether you bless a variable or not, it will still have the same scope ('availability').

    Moreover, have a look at some code that is posted here, and you will quickly get the hang of it.

    Hope this helps,

    Jeroen
    "We are not alone"(FZ)

Re: Bless to use my'd $var outside of block?
by arturo (Vicar) on Feb 14, 2001 at 20:43 UTC

    The typical use of bless is to identify a variable as an object belonging to a certain package / class. Of course, you want to be able to use objects outside the scope in which they're declared, but it's not bless that works this trick, it's simply the fact that the blessed reference is returned by your typical constructor:

    sub new { my ($class, @args) = @_; my $self = {}; # do something with @args, use it to populate hashref bless $self, $class; $self; #returns $self (reference to a hash) }

    This is what a constructor does, creates a new instance and returns it.

    Philosophy can be made out of anything. Or less -- Jerry A. Fodor

      I'd disagree that you are talking about "scope". $self goes out of scope at the end of the subroutine but because Perl uses reference counting, the object that $self references is not destroyed until all references to it go away.

      Since you return a reference to that object, the caller will (probably) have a reference to the object until their variable goes out of scope or they overwrite the value of that variable.

      Perl's reference counting means that you don't have to worry about things getting free()d before you are done with them (unlike C). You might have to worry a bit about things not getting free()d even though you are done with them, but I won't go into that here.

              - tye (but my friends call me "Tye")
Re: Bless to use my'd $var outside of block?
by wardk (Deacon) on Feb 14, 2001 at 20:47 UTC

    tame1

    to link a node (post), check out the Site How To

    Which is also on the right sidebar under "Information"