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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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[erix]: ah, that's really down at the heel point :)
[Eily]: LanX how dare you imply that I made a typo? It's true but still!
[Eily]: or is it a typo if the mistake was in my brain rather than in the process of typing?
[LanX]: they were talking about meatspace recently ...
[choroba]: a "thinko"
[erix]: my app (google, really) makes that 1530 km...
[Eily]: google tells me 1662 km ...
[LanX]: Nancy? Somewhere near Metz ...
[Eily]: must be km farenheit or something :P
[Eily]: wow, don't say that in Nancy LanX :P

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