Re: caching hashrefs in state

[Anonymous Monk]

Is this good practice?

not really -- if you're abstracting away a configuration singleton, don't allow direct access to the underlying hash (the state-d hash)

if you're going to allow direct access, just make it  our %hash

Also, like the other guy said , state $cfg never gets re-initialized,

the  state $cfg inside sub cfg_cache has nothing to do with the  my $cfg outside
$state_cfg doesn't get reinitialized, it holds a reference to $my_cfg, if you assign $my_cfg a new reference $state_cfg will not be affected, $state_cfg will still hold the original reference

The state perldoc says "variables will never be reinitialized" but it doesn't cover what happens if the variable is a reference.

Sure it does, a reference is a still just a variable, it won't be reinitialized

$ perl -le " use v5.10; sub f {  state $f = $_[0]; warn qq{ $f # @_ };
+ $f; } f({},$_) for 1 .. 4  "
 HASH(0x3f9b34) # HASH(0x3f9b34) 1  at -e line 1.
 HASH(0x3f9b34) # HASH(0x3f9b44) 2  at -e line 1.
 HASH(0x3f9b34) # HASH(0x3f9b94) 3  at -e line 1.
 HASH(0x3f9b34) # HASH(0x3f9b44) 4  at -e line 1.

state $f, once initialized deoesn't get reinitialized ,  state $f = $_[0]; only executes ONCE the very first time

However multiple assignments are multiple

$ perl -le " use v5.10; sub f {  state $f; $f = $_[0]; warn qq{ $f # @
+_ }; $f; } f({},$_) for 1 .. 4  "
 HASH(0x3f9b44) # HASH(0x3f9b44) 1  at -e line 1.
 HASH(0x3f9b54) # HASH(0x3f9b54) 2  at -e line 1.
 HASH(0x3f9ba4) # HASH(0x3f9ba4) 3  at -e line 1.
 HASH(0x3f9b44) # HASH(0x3f9b44) 4  at -e line 1.