[Chicago-talk] is this still on?

[Shlomi Fish]

Hi Steven,

On Mon, 18 May 2020 01:30:36 -0500
Steven Lembark <lembark at wrkhors.com> wrote:

> On Sun, 17 May 2020 15:01:45 -0400
> James E Keenan <jkeenan at pobox.com> wrote:
> 
> > On 5/17/20 12:49 PM, Jay S wrote:  
> > > Hi Perl mongers, I'm not sure if this list is still on|active.
> > > I hope everyone is doing well and staying sane.
> > > I haven't programmed in a long time and can't remember stuff.  How
> > > do make a list out of a hash?
> > > 
> > > Instead of:
> > > my $ClubID = $data{ClubID};
> > > my $GameCode = $data{GameCode};
> > > my $DateStarted = $data{DateStarted};
> > > my $GameType = $data{GameType};
> > > 
> > > I'd like to do something like this but can't remember the proper 
> > > incantation:
> > > my ($ClubID, $GameCode, $DateStarted, $GameType) = @data(qw[ClubID 
> > > GameCode DateStarted GameType]);  
> 
> You are looking for a "hash slice":
> 
> Quick refresher: The data type you are extracting from is specified
> by curly or square braces:
> 
>   foo{ ... }  access foo as a  hash
>   foo[ ... }  access foo as an an array
> 
> You are extracting a list of values (vs. key+value pairs) which 
> leaves you with:
> 
>     @foo{ ... }
> 
> to pull out the values of interest.
> 
> qw takes open-close pairs, I tend to prefer parens since they look 
> look more "list-ish" to me and doesn't get mistaken for an arrayref.
> 
> Leaves:
> 
>     my ($ClubID, $GameCode, $DateStarted, $GameType) 
>     = @data{ qw( GameCode DateStarted GameType ) };
> 
> or 
>     my @keyz = [ qw( GameCode DateStarted GameType ) ]; 
> 

You should use "(" instead of "[" and ")" instead of "]" there:

https://perl-begin.org/tutorials/bad-elements/#init_arrays_from_arrayrefs

my @keyz = ( qw( GameCode DateStarted GameType ) ); 

>     ...
> 
>     my ($ClubID, $GameCode, $DateStarted, $GameType) = @data{ @keyz };
> 
> or
> 
>     state $keyz = [ qw( GameCode DateStarted GameType ) ]; 
> 
>     ...
> 
>     my ($ClubID, $GameCode, $DateStarted, $GameType) = @data{ @$keyz };
> 
> 
> Note that perl recently added a "kv-slice" which returns the 
> keys and values using a '%' sigil instead of '@':
> 
>     my ($ClubID, $GameCode, $DateStarted, $GameType) = %data{ @keyz };
> 
> this would provide a list of key-value pairs suitable for assigning
> to a new hash (if you saw that while experimenting you mistyped a 
> '%' instead of a '@'.
> 
> Zei gesund
> 



-- 

Shlomi Fish       https://www.shlomifish.org/
Humanity - Parody of Modern Life - https://shlom.in/humanity

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    — https://www.shlomifish.org/humour.html

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