You can always disable prototypes, but I'm not sure if that's what you meant:

&doit( $codeRef );
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That works! I think I did something else though?

Update: I found the example on the disk image DVD from my old machine;

doit \&{ $codeRef };;
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---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"I'd rather go naked than blow up my ass"

Another way:

sub testit{ print 'hi' }

sub doit (&) { $_[0]->() }

$codeRef = \&testit;
doit { &$codeRef };
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update (after BrowserUk's response below) -

My suggestion adds next to nothing, since wrt to sub stacks, $ref->() is just syntactic sugar for &$ref or vice versa. The notation doit \&{ $subref } seems to be the right thing to do:

#!/usr/bin/perl
use Carp qw(cluck);
sub testit{ cluck 'hi',$/ };; 
sub doit (&) { print $_[0],$/;$_[0]->() };; 
$codeRef = \&testit;;
doit { &$codeRef };
__END__
CODE(0x955737c)
hi
 at coderef.pl line 3
        main::testit called at coderef.pl line 6
        main::__ANON__() called at coderef.pl line 4
        main::doit('CODE(0x955737c)') called at coderef.pl line 6
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#!/usr/bin/perl
use Carp qw(cluck);
sub testit{ cluck 'hi',$/ };; 
sub doit (&) { print $_[0],$/;$_[0]->() };; 
$codeRef = \&testit;;
doit \&{ $codeRef };
__END__
CODE(0x9f4c11c)
hi
 at coderef.pl line 3
        main::testit() called at coderef.pl line 4
        main::doit('CODE(0x9f4c11c)') called at coderef.pl line 6
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sub testit{ print 'hi' };;

sub doit (\&) { $_[0]->() };;

my $codeRef = \&testit;;

doit( &$codeRef );
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sub doit2 (&) { $_[0]->() };

doit2( sub { print 'hi2' });
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The first example isn't an option because the sub in question is in a module (threads::async()). Also it defeats the most common use case of an in-line bareblock.

The latter doesn't help as I only have (multiple) coderefs at the place of use. I could use async{ $coderef->( ... ) };, but I'm not keen on the doubling of the call overhead.

I just rediscovered async \&{ $codeRef };. I'm not sure if that's equally costly.

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"I'd rather go naked than blow up my ass"

We had this discussion recently¹, unfortunately you can't define a prototype which allows literal codeblocks and coderefs (resp. scalars) at the same time.

You can allow alternatives with (\[&$]) but alas there is no ([&$]) 8(

At least you can spare the curlies async \&$codeRef ; !

Cheers Rolf

¹) update see coderefs and (&) prototypes

A "variable" can be any one of the Perl variables we know of and in this case perl thinks it is supposed to be "private" -When I read your post I thought you were making a private subroutine to another subroutine- and which you just happened to not dereference as it should have been. Whereas a "scalar" is a sigil-preceded entity so in your case perl thinks you're passing a scalar dereference which might not be clear enough of a message !.

That's just an observation which I hope I can stand corrected and be clarified about.

#replicating the Origianl Post (strictures on):

my $coderef = sub {print "Hi There \n";};
sub doit(&){          
    &{$_[0]};
    }
doit($coderef);     #accessing a code ref from within a subroutine
                    #Without prototype-check disabling..
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#The same perl complaint is generated in the above code too

C:\Documents and Settings\m>perl -
sub testit{ print 'hi' };;
sub doit (&) { $_[0]->() };;
my $codeRef = \&testit;;
doit( $codeRef );;
__END__
Type of arg 1 to main::doit must be block or sub {} (not private varia
+ble) at -
line 4, near "$codeRef )"
Execution of - aborted due to compilation errors.
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I didn't think that strictures or local versus global variables had, or could have any bearing on the matter. And in the great scheme of things it doesn't--other than the secondary diagnostic message.

However, I think that your observation that the second part of the error message (not scalar dereference) (which I think is new from 5.10.0) is misleading, if not just plain wrong. In that what I was passing was a scalar containing a reference (to some code), not a dereference.

But having seen the difference in the message you've received when the scalar containing the reference is a lexical, it suggests (perhaps), that the presence of the & prototype modifies what the code producing the message sees in some way.

That is mildly confusing, but not hugely significant. As the messages identifying the source of the error are relatively new, perhaps they'll get honed as time goes on.

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"I'd rather go naked than blow up my ass"