Re: Converting Hashes to Objects

in reply to Converting Hashes to Objects

Inspiration whacked me in the head yesterday, and I realized that it was pretty easy to take an arbitrary hash reference and turn it into an object, so that instead of writing $hash->{key} I can just write $hash->key, saving two characters and giving me protection from typos. Enter Util::H2O:

I'm glad that you took the time and effort to create this software tool, as it seems to have gotten me unstuck on a line of code and with sitting on the fence in general. I know that meditations are typically where a person doesn't come to ask questions, but I think a meditation gets bonus points when it solves a problem for someone else, that being me today. I like to conserve vertical space for the collective scrollfingers of the monastery so present output, source, and questions in readmore tags:

I was trying to create a main data structure using a hash and ran aground in Re^6: implementing a scrabble-esque game on Termux III and how best to create a main data structure. At the time I wrote:

So I'm mystified that $vars{max_tiles} = 7; does not initialize, even demoralized. I had wanted to create a central data structure, and thought a hash would be the ticket. Let me ask this: Would I have an easier time housing and calling this data if I created an object out of it? Right now, I have to pass a reference and receive it as well; I think it's hideous: $ref_var = init_vars($ref_var); How would $vars{max_tiles} look like if it were blessed into a class?

Well, I found out today. The install goes well

$ scm Util::H2O
[sudo] password for hogan: 
--> Working on Util::H2O
Fetching http://www.cpan.org/authors/id/H/HA/HAUKEX/Util-H2O-0.06.tar.
+gz ... OK
Configuring Util-H2O-0.06 ... OK
Building and testing Util-H2O-0.06 ... OK
Successfully installed Util-H2O-0.06
1 distribution installed
$
[download]

Output:

$ ./2.3.up.pl 
abs is /home/hogan/Documents/hogan/2.3.up.pl
path1 is /home/hogan/Documents/hogan
path2 is /home/hogan/Documents/hogan/games
This script will build the above path2. Proceed? (y|n)y
exiting init
7
survived to read this
Can't locate object method "x" via package "Util::H2O::_5620e865a5b8" 
+at ./2.3.up.pl line 36.
$
[download]

Source:

#!/usr/bin/perl

use strict;    # multiplayer upwords
use warnings;
use 5.016;
use Path::Tiny;
use Data::Dump;

## paths and constraints

@ARGV or @ARGV = qw( one two three four );    # for testing

my $abs   = path(__FILE__)->absolute;
my $path1 = Path::Tiny->cwd;

my %var;                                      #main data structure
my $ref_var = \%var;

$var{abs} = $abs;
$var{cwd} = $path1;

$ref_var = init_vars($ref_var);
my ( $board, $heights ) = create_board($ref_var);
my @dictwords = create_dict($ref_var);
my @drawpile = create_draw_pile();


### re-wire for H2O
use Util::H2O;
my $hash = h2o $ref_var;
print $hash->max_tiles, "\n"; 
#$var{max_tiles} * @ARGV  > @drawpile and die "too many players for ti
+les\n"; 
# Can I get past this line?
$hash->max_tiles* @ARGV  > @drawpile and die "too many players for til
+es\n"; 
say "survived to read this";
#$hash->x("z");  # setter
dd $hash;

sub x {

my $value = shift;
say "$value";

}

sub init_vars {

  use Path::Tiny;
  use Data::Dump;
  use 5.016;
  use warnings;
  use POSIX qw(strftime);

  my $rvars = shift;
  my %vars  = %$rvars;

  my $script = $vars{abs};
  my $path1  = $vars{cwd};
  my $games  = "games";
  my $path2  = path( $path1, $games );
  say "abs is $abs";
  say "path1 is $path1";
  say "path2 is $path2";
  print "This script will build the above path2. Proceed? (y|n)";
  my $prompt = <STDIN>;
  chomp $prompt;
  die unless ( $prompt eq "y" );

  $vars{side}    = 9;
  $vars{d_file}  = path( "my_data", 'enable1.txt' );
  $vars{ca_name} = path( "my_data", "words.11108138.$vars{side}" );
  my $munge = strftime( "%d-%m-%Y-%H-%M-%S", localtime );
  $munge .= ".txt";
  $vars{save_file} = path( $path2, $munge )->touchpath;
  $vars{save_file}->append_utf8("Script executing is $script\n");

  # other initializations
  $vars{max_tiles} = 7;
  $vars{n_1}       = $vars{side} + 1;
  $rvars           = \%vars;
  #dd $rvars;
  say "exiting init";
  return ($rvars);
}

sub create_board {

  use warnings;
  use 5.016;
  my $rvars   = shift;
  my %vars    = %$rvars;
  my $board   = ( '.' x $vars{side} . "\n" ) x $vars{side};
  my $heights = $board =~ tr/./0/r;
  return ( $board, $heights );
}

sub create_dict {

  my $rvars = shift;
  my %vars  = %$rvars;

  use strict;    # was 7.word.pl before becoming subroutine 
  use warnings;
  use Path::Tiny;
  use Data::Dump;
  use 5.016;
  use POSIX qw(strftime);

  my $cachefilename = path( "my_data", "upwords." . $vars{n_1} );

  my $download_file = '/home/hogan/Documents/hogan/my_data/1.english.t
+xt';
  unless ( -s $cachefilename && -s $download_file ) {

    use LWP::Simple;

    my $url =
'https://storage.googleapis.com/google-code-archive-downloads/v2/code.
+google.com/dotnetperls-controls/enable1.txt';
    say "execution was here";
    getstore( $url, $download_file );

  }
## substitute q for qu

  my $dictionaryfile = path($download_file);
  my @dictwords;
  if ( -s $cachefilename ) {
    @dictwords = path($cachefilename)->lines( { chomp => 1 } );
  }
  unless ( -s $cachefilename ) {
    print "sub q for qu";
    @dictwords = path($dictionaryfile)->lines( { chomp => 1 } );
    s/qu/q/g for @dictwords;
    # some words shortened
    # cache the ones of maxtiles length
    @dictwords = grep( /^[a-z]{2,$vars{n_1}}\z/, @dictwords );
    $cachefilename->spew( join "\n", @dictwords, '' );
  }

  my $refDict = \@dictwords;
  return @dictwords;

}

sub create_draw_pile {

  use List::Util qw( shuffle );
  use warnings;
  use 5.016;

  my @drawpile = shuffle +    #  thanks to GrandFather 11108145
    ('a') x 7, ('b') x 3, ('c') x 4, ('d') x 5, ('e') x 8, ('f') x 3,
    ('g') x 3, ('h') x 3, ('i') x 7, ('j') x 1, ('k') x 2, ('l') x 5, 
+('m') x 5,
    ('n') x 5, ('o') x 7, ('p') x 3, ('q') x 1, ('r') x 5, ('s') x 6, 
+('t') x 5,
    ('u') x 5, ('v') x 2, ('w') x 2, ('x') x 1, ('y') x 2, ('z') x 1;
  return @drawpile;
}
__END__
[download]

The big win here is getting this line:

$var{max_tiles} * @ARGV > @drawpile and die "too many players for tiles\n";

from one that complained of unitialized values to

$hash->max_tiles* @ARGV > @drawpile and die "too many players for tiles\n";

so we finally pass this sanity check.

I tried to understand

$hash->x("z"); # setter

by writing the following

sub x {

my $value = shift;
say "$value";

}
[download]

, but this doesn't help the syntax not be an error so far.

Q1) How is a "setter" to be implemented?

Q2) Do I still have to pass this around as clumsily as I am with these hash references now. How do I edit out as much of that chaff as I can?

Q3) Is there now a better way to do this?

my $abs   = path(__FILE__)->absolute;
my $path1 = Path::Tiny->cwd;

my %var;                                      #main data structure
my $ref_var = \%var;

$var{abs} = $abs;
$var{cwd} = $path1;
[download]

Again, thx, haukex, for helping me off a dime.

Comment on Re: Converting Hashes to Objects Select or Download Code

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Re^2: Converting Hashes to Objects by haukex (Archbishop) on May 20, 2020 at 08:11 UTC
`my %vars = %$rvars;` A note on this: When you do this, you're creating a (shallow) copy of the hash, and if `$rvars` happens to be a Util::H2O object, you'd lose its methods. If that's not what you want, you'll have to work with the hash reference directly. In newer versions of Perl (>=5.22), there is an experimental feature that allows aliasing: `use experimental 'refaliasing'; my $rvars = { foo=>"bar" }; \my %vars = $rvars; # alias print $vars{foo}, "\n"; # prints "bar" $vars{abc} = "xyz"; # modifies $hashref's contents` [download] But since it's experimental, it's probably better to stick with `$rvars->{foo}` instead. Q1) How is a "setter" to be implemented? In the context of Util::H2O, getters/setters are created for every key that exists in the hash or is given as an "additional key" at the time of the `h2o` call. So for your `$hash->x("z")` to work, there'd need to be a key `x` in the hash or you need to specify it to the `h2o` function; you don't need to write your own `sub x`. Q2) Do I still have to pass this around as clumsily as I am with these hash references now. Q3) Is there now a better way to do this? TIMTOWTDI, here's how I might have written it without the module: `use Path::Tiny; use Time::Piece; my $ref_var = { abs => path(__FILE__)->absolute, cwd => Path::Tiny->cwd, }; init_vars($ref_var); print $ref_var->{save_file}, "\n"; sub init_vars { my $rvars = shift; # ... $rvars->{save_file} = path( $rvars->{cwd}, "games", localtime->strftime("%d-%m-%Y-%H-%M-%S.txt") )->touchpath; # ... }` [download] And with the module, one can write: `use Path::Tiny; use Time::Piece; use Util::H2O; my $ref_var = h2o { abs => path(__FILE__)->absolute, cwd => Path::Tiny->cwd, }, qw/ save_file ... /; init_vars($ref_var); print $ref_var->save_file, "\n"; sub init_vars { my $rvars = shift; # ... $rvars->save_file( path( $rvars->cwd, "games", localtime->strftime("%d-%m-%Y-%H-%M-%S.txt") )->touchpath ); # ... }` [download]	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^2: Converting Hashes to Objects
by haukex (Archbishop) on May 20, 2020 at 08:11 UTC

my %vars = %$rvars;

A note on this: When you do this, you're creating a (shallow) copy of the hash, and if $rvars happens to be a Util::H2O object, you'd lose its methods. If that's not what you want, you'll have to work with the hash reference directly. In newer versions of Perl (>=5.22), there is an experimental feature that allows aliasing:

use experimental 'refaliasing';
my $rvars = { foo=>"bar" };
\my %vars = $rvars;      # alias
print $vars{foo}, "\n";  # prints "bar"
$vars{abc} = "xyz";      # modifies $hashref's contents
[download]

But since it's experimental, it's probably better to stick with $rvars->{foo} instead.

Q1) How is a "setter" to be implemented?

In the context of Util::H2O, getters/setters are created for every key that exists in the hash or is given as an "additional key" at the time of the h2o call. So for your $hash->x("z") to work, there'd need to be a key x in the hash or you need to specify it to the h2o function; you don't need to write your own sub x.

Q2) Do I still have to pass this around as clumsily as I am with these hash references now.

Q3) Is there now a better way to do this?

TIMTOWTDI, here's how I might have written it without the module:

use Path::Tiny;
use Time::Piece;

my $ref_var = {
    abs => path(__FILE__)->absolute,
    cwd => Path::Tiny->cwd,
};

init_vars($ref_var);
print $ref_var->{save_file}, "\n";

sub init_vars {
    my $rvars = shift;
    # ...
    $rvars->{save_file} = path( $rvars->{cwd}, "games",
        localtime->strftime("%d-%m-%Y-%H-%M-%S.txt") )->touchpath;
    # ...
}
[download]

And with the module, one can write:

use Path::Tiny;
use Time::Piece;
use Util::H2O;

my $ref_var = h2o {
    abs => path(__FILE__)->absolute,
    cwd => Path::Tiny->cwd,
}, qw/ save_file ... /;

init_vars($ref_var);
print $ref_var->save_file, "\n";

sub init_vars {
    my $rvars = shift;
    # ...
    $rvars->save_file( path( $rvars->cwd, "games",
        localtime->strftime("%d-%m-%Y-%H-%M-%S.txt") )->touchpath );
    # ...
}
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