Can't write values from sorted array of structs

maschwarz has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to sort and a comma-separated list and insert a line from another file. I created an array of structs as a test, but it wouldn't print outside of dumper, what am I doing wrong

use strict;

use warnings;

use Class::Struct;

package Carrier_Info;

 

struct Carrier_Info => {

          name => '$',

          abbrev => '$',

};

 

my $aa="TH";

my @carriers;

{

    #method 2

    push @carriers, Carrier_Info->new(name => "Paul Lalli", abbrev =>"
+PL");

    push @carriers, Carrier_Info->new(name => "Travis Hervey", abbrev=
+> $aa);

               

                my $xyz;

                $xyz = pop(@carriers);

                my $ppp = $xyz->{name};

                print "which name is $ppp\n";

}
[download]

This prints either "Array(0x)", "Hash(0x )" or nothing. I'm expecting it to print "Travis Harvey". Once I understand using structs I can proceed with my real perl program Michael

Comment on Can't write values from sorted array of structs Download Code

Replies are listed 'Best First'.
Re: Can't write values from sorted array of structs by hippo (Bishop) on Oct 28, 2020 at 17:07 UTC
I'm afraid that your code as supplied doesn't compile for me. Using Class::Struct 0.65 with perl v5.20.3 I see: `syntax error at 11123269.pl line 11, near "struct Carrier_Info" Execution of 11123269.pl aborted due to compilation errors.` [download] This seems reasonable because the documentation suggests that the arguments to `struct` should be within brackets. Is this really the code you are running? Update: here's an SSCCE showing what I think you expect to be output. `#!/usr/bin/env perl use strict; use warnings; package Carrier_Info; use Class::Struct; struct (Carrier_Info => { name => '$', abbrev => '$', }); my $aa = "TH"; my @carriers; push @carriers, Carrier_Info->new(name => "Paul Lalli", abbrev =>"PL") +; push @carriers, Carrier_Info->new(name => "Travis Hervey", abbrev=> $a +a); my $xyz = pop(@carriers); my $ppp = $xyz->name; print "which name is $ppp\n";` [download] I won't claim this is the neatest as I never use Class::Struct directly but hopefully it will serve as an illustration. 🦛	[reply] [d/l] [select]
Re^2: Can't write values from sorted array of structs by tobyink (Canon) on Oct 29, 2020 at 03:13 UTC
"This seems reasonable because the documentation suggests that the arguments to struct should be within brackets." The parentheses aren't important. OP puts `use Class::Struct` before the `package` statement, so the `struct` function is being imported into `main` instead of into `Carrier_Info`. toby döt ink	[reply] [d/l] [select]
Re: Can't write values from sorted array of structs by tobyink (Canon) on Oct 29, 2020 at 09:43 UTC
This is your biggest issue: `use Class::Struct; package Carrier_Info;` [download] You want: `package Carrier_Info; use Class::Struct;` [download] Why? Because the `struct` "keyword" isn't a keyword in the sense of the Perl keyword API; it's not lexically scoped. It's a sub exported to a package, and by importing it before your `package` statement, you're exporting it outside your package (probably into `main`) instead of into your package. Better yet, leave the `package Carrier_Info;` part out entirely. It's not needed, and seems to suggest you think you need to define the `Carrier_Info` package yourself; the whole point of using `Class::Struct` is to allow it to define the `Carrier_Info` package for you! Lesser issue (because while it stops your code from working, it's not a syntax error), but still an issue: `my $ppp = $xyz->{name};` [download] You want: `my $ppp = $xyz->name;` [download] toby döt ink	[reply] [d/l] [select]

Back to Seekers of Perl Wisdom