Beefy Boxes and Bandwidth Generously Provided by pair Networks
more useful options
 
PerlMonks  

Re^3: problem with array of hashes

by Don Coyote (Pilgrim)
on Oct 09, 2012 at 21:55 UTC ( #998090=note: print w/replies, xml ) Need Help??


in reply to Re^2: problem with array of hashes
in thread problem with array of hashes

There may be good reason to qualify the seemingly redundant use of the arrow dereferencer between the deepest subscripts. If not solely to understand what is happening in a different way.

...is the same as

${${$VAR1}[0]}{41}

The manner in which dereferencing occurs is different but the result is the same. Most feel the arrow manner is simpler on the brain, being more intuitive once you have grasped the notion of dereferencing.

lets reduce the complexity for a moment

my $VAR2 = [ 101, 201, 42 ]; print $VAR2->[0],' ',${$VAR2}[0]; ------- 101 101

we can now reach the first level reference to the array and by all accounts either syntax is fairly comprehensible.

Lets increase the complexity back up.

my $VAR3 = [ {'101'=>'hel', '201'=>'lo', '42'=>'world'} ]; print $VAR3->[0]->{42},' ',${${$VAR3}[0]}{42}; ------- world world

You can already see the way of the arrow is clearer as the start of the dereference does not accumulate the scalar sigil for each depth of level of complexity. And to be fair this starts literally looking subsequently more expensive too.

The toppler of the cake is that the arrow way also adds the optimisation of saying, hey you know what, seeing as we're already dereferencing here lets not bother making a christmas decoration out of the expression and voila! you get...

print $VAR3->[0]{42}; --- world

Making the array actual, you use dereffing where its needed, not between the first level subscript but between the second level subscript.

my @VAR4 = ( {'101'=>'hel', '201'=>'lo', '42'=>'world'},' dereffed' ); print @VAR4,' ',$VAR4[0]->{42},' ',${$VAR4[0]}{42}; ------- HASH(0x3e81a4) dereffed world world

Comparing the position of the arrow between $VAR3 and $VAR4[0], it would seem this gives us a qualifier for telling us when in a complex structure a 'reference to' or 'an actual' hash/array resides at the first level.

The reason being data structures only hold scalars. The very reason for the requirement of referencing. As a reference to a complex structure is a scalar.

And this of course means the arrow way can safely bah humbug the merry season with all the capacity of your ram.


my $ah={h=>'a'};print %$ah for 0..2;

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://998090]
help
Chatterbox?
[james28909]: like all the subs calling get_data get_array get_ect, you could just use get_data. once you send the data to get_data, check if it is a hash or an array ect. and do functions for each, in one sub
[james28909]: that looks like it would be alot more work than just renaming the sub though lol
[Lady_Aleena]: james28909, did you even look at the subs?
[james28909]: yes
[Lady_Aleena]: And you see how the first two are vastly different than the third, right?

How do I use this? | Other CB clients
Other Users?
Others having an uproarious good time at the Monastery: (7)
As of 2017-05-24 04:58 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?