Re^2: Mixed lvalue/rvalue sub function

Hi, I realize that the lvalue syntax looks a little weird, maybe I should kick it out and just have:

$obj->header('test'); # Get header 'test'
$obj->header('test','new value'); # set header test
$obj->header;         # Get all headers as hash
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You C++-ish suggestion:

my $hdr_slot = $self->header ('test');
$hdr_slot = "new value"; # Set
print "New header: $hdr_slot\n"; # Get
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doesn't work in Perl because there all objects are references (to talk C++: from type *myclass not myclass). So assigning to $hdr_slot would make this variable a string with the value "new value" and would remove the reference to the object. Overloading the '=' operator only is used for generating temp copies for operators like '+=', so far I know.

The only way to do this is to tie a class to $hdr_slot. Then you can define a STORE method which gets called at every '='. See 'perldoc perltie' for more.

I read all this in the book 'Object Oriented Perl' just two weeks ago.

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Re^3: Mixed lvalue/rvalue sub function by elmex (Friar) on Apr 18, 2008 at 13:44 UTC
Ah, yes, you are of course completely right, I guess I did too much C++ recently :) Alternatively you could return a reference to the header, of course. But it would look kinda more ugly than the simple optional argument solution: `my $slot = $self->header ('test'); $$slot = "New value"; print "Value for header: $$slot"; # or even $slot, if you overload the + stringification` [download]	[reply] [d/l]
Re^4: Mixed lvalue/rvalue sub function by mscharrer (Hermit) on Apr 18, 2008 at 17:18 UTC
If you like to start using lvalue function, you should know that they are still marked as experimental (at least in Perl 5.8). perlsub says: WARNING: Lvalue subroutines are still experimental and the implementation may change in future versions of Perl.	[reply]