Question - anonymous recursive functions

[Alex]

Hello,

I want a function to be private inside a module, so - I made it
anonymous. Also I want it to be recursive - how to do that?

use diagnostics;
use warnings;
use strict;

my $F1 = sub($)
{
my $n = shift;
print "$n\n";
$F1->($n + 1) if $n < 10;
};

F1(0);

This gives me the error message:

------------------------

Global symbol "$F1" requires explicit package name at tp205.pl line
27.
Execution of tp205.pl aborted due to compilation errors (#1)
(F) You've said "use strict vars", which indicates that all
variables
must either be lexically scoped (using "my"), declared beforehand
using
"our", or explicitly qualified to say which package the global
variable
is in (using "::").

Uncaught exception from user code:
Global symbol "$F1" requires explicit package name at tp205.pl line
27.
Execution of tp205.pl aborted due to compilation errors.
at tp205.pl line 30

 

[Alex]

Hello,

I want a function to be private inside a module, so - I made it
anonymous. Also I want it to be recursive - how to do that?

use diagnostics;
use warnings;
use strict;

my $F1 = sub($)
{
my $n = shift;
print "$n\n";
$F1->($n + 1) if $n < 10;

};

F1(0);

This gives me the error message:

------------------------

Global symbol "$F1" requires explicit package name at tp205.pl line
27.
Execution of tp205.pl aborted due to compilation errors (#1)
(F) You've said "use strict vars", which indicates that all
variables
must either be lexically scoped (using "my"), declared beforehand
using
"our", or explicitly qualified to say which package the global
variable
is in (using "::").

Uncaught exception from user code:
Global symbol "$F1" requires explicit package name at tp205.pl line
27.
Execution of tp205.pl aborted due to compilation errors.
at tp205.pl line 30

-------------------------

Please help
Thanks
Alex

My mistake above - I call it as

$F1->(0);

But the question remains....

 

[Alexander Bartolich]

[...]
my $F1 = sub($)
{
my $n = shift;
print "$n\n";
$F1->($n + 1) if $n < 10;
};
[...]
Global symbol "$F1" requires explicit package name at tp205.pl line
27.

The definition of »$F1« is finished only at the »};«.
Hence you can use it only afterwards.
The fix is trivial.

my $F1;
$F1 = sub($)
{
my $n = shift;
print "$n\n";
$F1->($n + 1) if $n < 10;
};

 

[Alex]

Quick and easy!
Thank you, Alexander

[...]
my $F1 = sub($)
{
my $n = shift;
print "$n\n";
$F1->($n + 1) if $n < 10;
};
[...]
Global symbol "$F1" requires explicit package name at tp205.pl line
27.

The definition of »$F1« is finished only at the »};«.
Hence you can use it only afterwards.
The fix is trivial.

my $F1;
$F1 = sub($)
{
my $n = shift;
print "$n\n";
$F1->($n + 1) if $n < 10;
};

--
Brüder, in die Tonne die Freiheit,
Brüder, ein Stoppschild davor.
Egal was die Schwarzen Verlangen
Rufen wir: Ja! Brav im Chor.

 

[Peter Makholm]

I want a function to be private inside a module, so - I made it
anonymous. Also I want it to be recursive - how to do that?

You can also use namespace::clean for private functions:

package Foo;

use namespace::clean qw(foo);

sub foo { return 42 }
sub bar { return foo() + 1 }

1;

This would effectivly make the foo function private to Foo.pm.

//Makholm

 

[Marc Girod]

You can also use namespace::clean for private functions:

Thanks!
The best answers are are those to questions you were too stupid to
make.
I, in this case.

Marc

 

[Peter Makholm]

You can also use namespace::clean for private functions:

I don't really like this interface, so I wrapped it up as an attribute
for subroutines. Soon to be available on CPAN as Sub:rivate[0] or at
Github[1].

The you could just write:

package Foo;

use Sub:rivate;

sub foo rivate {
return 42;
}

sub bar {
return foo() + 1;
}

1;

0) Allready uploaded, just waiting for the indexer
1) http://github.com/pmakholm/sub-private-perl/tree/master

//Makholm