How to assign a Hash - newbie

[evillen]

Hi

Is there a more elegant to assign one hash to another - the solution
below works:

my $table = 'c';
my %dbitems;

if($table eq 'a'){%dbitems = %a}
elsif($table eq 'b'){%dbitems = %b}
elsif($table eq 'c'){%dbitems = %c}
elsif($table eq 'd'){%dbitems = %d}
elsif($table eq 'e'){%dbitems = %e}
elsif($table eq 'f'){%dbitems = %f}
elsif($table eq 'g'){%dbitems = %g}

but I hoped something like this would achieve the same:

my $table = 'c';
my %dbitems = %.$table;

I've tried variations but I get syntax errors such as:
"Can't use string ("c") as a HASH ref while "strict refs"" or "Only
hard references are allowed by "strict refs""

Thanks for any help
NJH

 

[anno4000]

Hi

Is there a more elegant to assign one hash to another - the solution
below works:

my $table = 'c';
my %dbitems;

if($table eq 'a'){%dbitems = %a}
elsif($table eq 'b'){%dbitems = %b}
elsif($table eq 'c'){%dbitems = %c}
elsif($table eq 'd'){%dbitems = %d}
elsif($table eq 'e'){%dbitems = %e}
elsif($table eq 'f'){%dbitems = %f}
elsif($table eq 'g'){%dbitems = %g}

but I hoped something like this would achieve the same:

my $table = 'c';
my %dbitems = %.$table;

You need an auxiliary hash (%sel below) to do that in a sane manner.
Untested:

my %sel;
@sel{ 'a' .. 'g'} = \ ( %a, %b, %c, %d, %e, %f, %g);

my $table = 'c';
my %dbitems = %{ $sel{ $table} };

You may be able to work with the hashrefs from %sel directly, without
copying the hash to %dbitems:

my $dbitems = $sel{ $table};

....and then use "$dbitems->{ $key}" instead of "$dbitems{ $key}".

Anno

 

[Mumia W.]

Hi

Is there a more elegant to assign one hash to another - the solution
below works:

my $table = 'c';
my %dbitems;

if($table eq 'a'){%dbitems = %a}
elsif($table eq 'b'){%dbitems = %b}
elsif($table eq 'c'){%dbitems = %c}
elsif($table eq 'd'){%dbitems = %d}
elsif($table eq 'e'){%dbitems = %e}
elsif($table eq 'f'){%dbitems = %f}
elsif($table eq 'g'){%dbitems = %g}

but I hoped something like this would achieve the same:

my $table = 'c';
my %dbitems = %.$table;

I've tried variations but I get syntax errors such as:
"Can't use string ("c") as a HASH ref while "strict refs"" or "Only
hard references are allowed by "strict refs""

Thanks for any help
NJH

Go into a command prompt and type

perldoc -q "variable as"

The Perl documentation on your system should explain this.

When you're done reading that, type "perldoc perlfaq"

 

[mattsteel]

(e-mail address removed) ha scritto:

Hi

Is there a more elegant to assign one hash to another - the solution
below works:

my $table = 'c';
my %dbitems;

if($table eq 'a'){%dbitems = %a}
elsif($table eq 'b'){%dbitems = %b}
elsif($table eq 'c'){%dbitems = %c}
elsif($table eq 'd'){%dbitems = %d}
elsif($table eq 'e'){%dbitems = %e}
elsif($table eq 'f'){%dbitems = %f}
elsif($table eq 'g'){%dbitems = %g}

but I hoped something like this would achieve the same:

my $table = 'c';
my %dbitems = %.$table;

I've tried variations but I get syntax errors such as:
"Can't use string ("c") as a HASH ref while "strict refs"" or "Only
hard references are allowed by "strict refs""

Thanks for any help
NJH

Maybe this is what you want.

my $table = 'c';
my %dbitems;
eval "\%dbitems = \%$table";

M.

 

[evillen]

You need an auxiliary hash (%sel below) to do that in a sane manner.
Untested:

my %sel;
@sel{ 'a' .. 'g'} = \ ( %a, %b, %c, %d, %e, %f, %g);

my $table = 'c';
my %dbitems = %{ $sel{ $table} };

You may be able to work with the hashrefs from %sel directly, without
copying the hash to %dbitems:

my $dbitems = $sel{ $table};

...and then use "$dbitems->{ $key}" instead of "$dbitems{ $key}".

Anno

Thanks guys, however I was advised to try using a HOH - so now I am
trying this code:


#START
#!c:/perl/bin/perl.exe -w

use strict;
use diagnostics;

#-------------------------------------------------
#Description of hashes is: fieldname[label,length,category,tick,order]
my %HoH = (
names => {
fore => ['Frank','Alex','Wayne'],
sur => ['Lampard','Ferguson','Rooney'],
},
places => {
north => ['Burnley', 'Chester', 'Doncaster'],
south => ['Brighton', 'Cheltenham', 'Dover'],
},
);

my $table = "names";
my %Hash = $HoH{$table};

print "My \%Hash is: ", %Hash;

#END

however this won't assign a Hash to Hash as expected. How do I assign
the name/value pairs of "names" to %Hash?

NJH

 

[mattsteel]

my $table = "names";
my %Hash = $HoH{$table};

print "My \%Hash is: ", %Hash;

#END

however this won't assign a Hash to Hash as expected. How do I assign
the name/value pairs of "names" to %Hash?

NJH

my %Hash = %{$HoH{$table}}

 

[evillen]

my %Hash = %{$HoH{$table}}

Many thanks Matt - it's been a long day....