YAML Alias

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

Hi, I'm trying to setup a YAML file using YAML::XS, now, for the most part it's fine if I use a standard YAML format, but, I'd like to include defaults and aliases, but, whenever I load a "defaulted" block it's in a << hash first.

#!/usr/bin/env perl

use Data::Dumper;
use YAML::XS;

my $config = LoadFile('config.yml')->{'production'};

print Dumper($config);
[download]

defaults: &defaults
  src:
    host: localhost
    database: db
    username: root
    password:
  nfs: /tmp

development:
  <<: *defaults

test:
  <<: *defaults

production:
  <<: *defaults
  nfs: ian
[download]

I'd also ideally like to be able to override the defaults. If my block looks like this:

production:
  src:
    host: localhost
    database: db
    username: root
    password:
  nfs: /tmp
[download]

All is well and fine. Any tips gratefully received, the alias stuff comes from a ruby background.

Comment on YAML Alias Select or Download Code

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Re: YAML Alias (xml) by Anonymous Monk on Apr 21, 2015 at 23:17 UTC
, for the most part it's fine if I use a standard YAML format, but, I'd like to include defaults and aliases, but, whenever I load a "defaulted" block it's in a << hash first. So why is this a problem? Why do you think so? What should happen instead? I'd also ideally like to be able to override the defaults. If my block looks like this: What do you mean by that exactly, can you give input/output? Any tips gratefully received, the alias stuff comes from a ruby background And is it something thats in the current yaml spec? I think this is your problem, I don't think `'<<' : Merge keys from another mapping.` is a generally available YAML feature update: hah from 2009 A fix for merge keys in YAML::XS, YAML::Syck and the wikipedia reference is gone http://en.wikipedia.org/w/index.php?title=YAML&oldid=328219776#Data_merge_and_references so this isn't a widely supported feature Yeah, YAML, its dumb :) Maybe when YAML tools improve ten fold, brave folks will look at YAML again, but most will still stick with JSON :)	[reply] [d/l]

Replies are listed 'Best First'.

Re: YAML Alias (xml)
by Anonymous Monk on Apr 21, 2015 at 23:17 UTC

, for the most part it's fine if I use a standard YAML format, but, I'd like to include defaults and aliases, but, whenever I load a "defaulted" block it's in a << hash first.

So why is this a problem? Why do you think so? What should happen instead?

I'd also ideally like to be able to override the defaults. If my block looks like this:

What do you mean by that exactly, can you give input/output?

Any tips gratefully received, the alias stuff comes from a ruby background

And is it something thats in the current yaml spec? I think this is your problem, I don't think '<<' : Merge keys from another mapping. is a generally available YAML feature

update: hah from 2009 A fix for merge keys in YAML::XS, YAML::Syck and the wikipedia reference is gone http://en.wikipedia.org/w/index.php?title=YAML&oldid=328219776#Data_merge_and_references so this isn't a widely supported feature

Yeah, YAML, its dumb :) Maybe when YAML tools improve ten fold, brave folks will look at YAML again, but most will still stick with JSON :)

[reply]
[d/l]