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Re^3: Entering the land of Perl

by 2teez (Priest)
on Apr 05, 2013 at 03:17 UTC ( #1027059=note: print w/replies, xml ) Need Help??

in reply to Re^2: Entering the land of Perl
in thread Entering the land of Perl

Hi manbroski,

"..Notice that I have to dereference it after the passage.." Why is that?

Did you also notice your subroutine sort_and_print_hash_keys definition

sub sort_and_print_hash_keys (\%) {..
and how you eventually used the it like so:
sort_and_print_hash_keys(%letters); # you passed a hash variable not a + hash ref.
".. But as far as the prototype passing, I was certain that it enforces a pass by reference..."

If I may suggest, you will do well yielding the wisdom of jwkrahn, as regard the usage of prototype for this reason:

When you use a reference prototype, like "\$", "\@", "\%" "...those symbols don't actually say that you must pass in a scalar reference, an array reference, and a hash reference. Rather, they say you must pass in a scalar variable, an array variable, and a hash variable. That means that the compiler insists upon seeing a properly notated variable of the given type, complete with "$", "@", or "%" in that slot. You must not use a backslash. The compiler silently supplies the backslash for you... "
from Far More than Everything You've Ever Wanted to Know about Prototypes in Perl -- by Tom Christiansen
-- by liverpole, under subheading Problems with Reference Prototypes

Hope this helps.

If you tell me, I'll forget.
If you show me, I'll remember.
if you involve me, I'll understand.
--- Author unknown to me

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[choroba]: just one of its angles, in fact
[LanX]: <|--
[choroba]: Reminds me of an old joke about an orchestra...
erix imagines that in a true Lancs accent
[choroba]: so a Czech orchestra rehearses a new piece by a German composer
LanX LOL of the day ... the Turkish Anonymous Alcoholics stopped their "No to alcohol" campaign for political reasons ...
LanX omg my browser is posting again on its own ...
[LanX]: choroba: GREAT JOKE! xD

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