Writing a Perl hash to disk to be read by Python

Question

How can I write a Perl hash to file, in such a way that it can be read from Python?

For example:

#!/usr/bin/perl
my %h = (
   foo => 'bar',
   baz => ['a', 'b', 'c'],
   raz => {
       ABC => 123,
       XYZ => [4, 5, 6],
   }
);

dumpHash('/tmp/myhash', %h);

... and

#!/usr/bin/python
h = readHash('/tmp/myhash')
print h

# {
#  'foo': 'bar', 
#  'baz': ['a', 'b', 'c'],      
#  'raz': {
#          'ABC': 123, 
#          'XYZ': [4, 5, 6]
#         }
# }

I normally use Perl's built-in Storable to serialize hashes. I see Python has a Storable reader, but it's not part of the standard distribution.

Is there a way to do this with standard built-ins from both languages.

I've never used Perl before, but my suggestion would be to dump it to json. Then in python you can use `json.loads` to load it to a dict. — Brobin, Jul 31 '15 at 18:02
JSON should work. Libraries for it ship with the core distro of both languages. — nobody, Jul 31 '15 at 18:02
As far as I can tell, the only mechanism for this that ships with Perl is `Storable` which of course Python doesn't know about. I'll probably just suck it up and install Perl's JSON module. — ajwood, Jul 31 '15 at 18:45
@ysth, It does since 5.14. "JSON::PP was first released with perl v5.13.9" — ikegami, Jul 31 '15 at 19:51

stevieb · Accepted Answer · 2015-07-31T18:30:50.273

0

I missed the 'builtin' requirement on first read of your question, but I digress. JSON is not a built-in in Perl, so you'll have to install via CPAN. Nonetheless, this is probably one of the most efficient and compatible ways to do it.

Perl:

use warnings;
use strict;

use JSON;

my $file = 'data.json';

my %h = (
   foo => 'bar',
   baz => ['a', 'b', 'c'],
   raz => {
       ABC => 123,
       XYZ => [4, 5, 6],
   }
);

my $json = encode_json \%h;

open my $fh, '>', $file or die $!;

print $fh $json;

close $fh or die $!;

Python:

import json

file = 'data.json';
data = json.loads(open(file).read())

print(data)

edited Jul 31 '15 at 18:30

answered Jul 31 '15 at 18:25

stevieb

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I was hoping to find a solution with only built-in stuff, but I think you're right that I might as well bite the bullet and grab a CPAN module – ajwood Jul 31 '15 at 18:28
Just don't name your Python script `json.py` or it'll conflict with the actual json module. – stevieb Jul 31 '15 at 18:32
If you're going to install JSON(.pm), you might as well install JSON::XS and use that instead. – ikegami Jul 31 '15 at 19:53

Writing a Perl hash to disk to be read by Python

1 Answers1