You're explicitly overwriting the globref with a scalar. <P.You need to use the right syntax to assign to the SCALAR slot of the referenced glob. 

[ 7:53:35.32] P:\test>perl -l
my $globref = \do { local *GLOB };
print $globref;

## Assign to the SCALAR slot in the glob referenced by $globref
${ *$globref } = 123456789;

print $globref; ## Still a GLOB
print ${ *$globref }; ## Contains our value

## This is where the trouble comes in.
*$globref = sub{ print 'test' };

print ${ *$globref }, $/, &{ *$globref };
^Z
GLOB(0x224fc8)
GLOB(0x224fc8)
123456789
Not a GLOB reference at - line 13.

[download]

However, I did just discover this. 


[ 7:56:55.39] P:\test>perl -l
my $globref = do { local *GLOB; \*GLOB; };
print $globref;

## Assign to the SCALAR slot in the glob referenced by $globref
${ *$globref } = 123456789;

print $globref; ## Still a GLOB
print ${ *$globref }; ## Contains our value

## This is where the trouble comes in.
*$globref = sub{ print 'test' };

print ${ *$globref }, $/, &{ *$globref };
^Z
GLOB(0x1824284)
GLOB(0x1824284)
123456789
test
123456789
1

[download]

If I return the reference to the localised GLOB from with the do block, then everything works fine, without the need to pre-assign something to the actual GLOB before hand.

I'm pretty sure that I picked up on the idiom of 

my $globref = \ do{ local *GLOB; };

[download]

from a usually reliable (and wizardly:) source, but I'll need to check that.

As I understand it, localising the GLOB effectively give you access to a new (anonymous) typeglob ensuring that if the code is called multiple times, you get a new once each time, without needing to go the Symbol route of creating sequence numbered globs in a special namespace.

However, my understanding may well be wrong. This could just be what I assumed the do local construct was doing. Hmmm. Off to try and relocate some sources and refresh my memory.

In reply to Re^3: Assigning to the CODE slot of a GLOB whose REF is held in a lexical? by BrowserUk
in thread Assigning to the CODE slot of a GLOB whose REF is held in a lexical? by BrowserUk

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