For example,

Let the base YAML be:

# base.yml
alpha: true
beta: false
gamma: true
data:
    delta: false
    kappa: true
    theta: false

Let the extended YAML be:

# extended.yml
extends: 'base.yml'
alpha: false
beta: true
data:
    delta: true
    kappa: false

When you call

YAML.ext_load_file 'extended.yml'

the returned YAML value results in

alpha: true
beta: true
gamma: true
data:
    delta: true
    kappa: true
    theta: false

The values of alpha and kappa should actually be false since they are over-written in extended YAML

I thought this package would be a very nice addition to a mechanism I have in place to specify settings/configurations...but it seems the order in which merged files end up in the final result are giving not the results I would desire.

My settings syntax is as follows:

block:
- rule1:
   setting a
   setting b
   ....
- rule2:
  setting c 
  ...

The rules determine on what settings get applied. It is legal to list the same rule multiple times (that is why it is an array). If a setting is repeated, the 'last one wins' which feels most intuitive and follows what yaml does.

However in the following example:

# base.yaml
---
blockX:
- playground:
    macros:
      M_BASE: ja
      M_REPLACE: to_be_replaced
...

# settings.yaml
---
extends:
  - 'base.yaml'
blockX:
- playground:
    macros:
      M_DERIVE: ja
      M_REPLACE: replaced
...

Gives as result:

---
blockX:
- playground:
    macros:
      M_DERIVE: ja
      M_REPLACE: replaced
- playground:
    macros:
      M_BASE: ja
      M_REPLACE: to_be_replaced
...

In which it is unfortunate that the extended base comes last in the list, as a result when I process the file the macros result in:

M_DERIVE: ja
M_BASE: ja
M_REPLACE: to_be replaced ---> should haven bee 'replaced'

Would it be difficult to put the merged list in the order from base --> derived? (maybe optional)

According to the docs:

If you want to inherit from several files, you can specify a list (Array) of files. They are merged from top to bottom, so the latest file "wins" - that means it overwrites duplicate values if they exist with the values in the latest file where they occur.

This however is not true. Actually the order seems to be exactly the opposite!
The later entries in the extends array have precedence over the earlier ones.
Additionally, the own keys of the file that extends multiple others tend to come first i.e. own entries first, then extended ones (the order is messed up, but they correctly overwrite the values of parent entries).

As an example, let's have the following 3 files:

# parent1.yml
parent1_key_overwritten: parent1
parent1_key_own: parent1

# parent2.yml
parent1_key_overwritten: parent2
parent2_key_own: parent2

# child.yml
extends:
  - parent1.yml
  - parent2.yml

some_other_key: child

The expected result of YAML.ext_load_file 'child.yml' should then be:

parent1_key_overwritten: parent2
parent1_key_own: parent1
parent2_key_own: parent2
some_other_key: child

but instead, what we get is:

some_other_key: child
parent1_key_overwritten: parent1
parent1_key_own: parent1
parent2_key_own: parent2

if the yaml filesfile.ymland other.yml are in a directory called config

and the call YAML.ext_load_file 'config/file.yml' is issued with cwd one above config
then the other files that are extended are not found

# file.yml
extends: 
 - 'other.yml' # not found
 - 'config/other.yml'  # not found either

does not work with path relative to file.yml or relative to cwd

Please see the failing spec here: #15

I've been using yaml_extend and like it. Thanks!

I now need to pass the symbolize_names option to Psych. Specifically I need to pass symbolize_names: true.
I don't see a way to do this. Is there a way to pass options thru to Psych? Am I overlooking something?

Hi,

I was trying to use your gem in the following fashion -

nested_config.yml

options:
  extends: 'child_config.yml'

child_config.yml

blah: 'blah'

I want to be able to access the config like so config.options.blah rather than config.blah because I put the extends underneath the options key. Maybe I am doing something wrong? How do I achieve this?

Also, can you add multiple extends in a file?

As I understand, extends seems to add the extended files at the end of the main file, and not at the beginning.

This is a little counter intuitive (since everywhere else, extend or include means "first use the content of the included file"), and causes issues when using anchors.

Example use case:

This is a valid YAML:

one: &one
  hello: world

menu:
  <<: *one

While this is not a valid YAML:

menu:
  <<: *one

one: &one
  hello: world

So, if I wish to provide "blocks of YAML" that can be used by other blocks, I cannot use the extend functionality. The below example is broken:

# test.rb
require 'yaml_extend'
data = YAML.ext_load_file 'child.yml'
puts data.to_yaml

# child.yml
extends:
- parent.yml

menu:
  <<: *one
  <<: *two

# parent.yml
one: &one
  hello: world

two: &two
  hi: world
  hey: world

I know there are other ways around it, but my use case was more naturally implemented with anchors, and now I know they cannot be used this way.

Is there any reason for the included content to come last and not first?

Hi,
I've been looking to use this library and was wondering if it only works for values of type String.
Would it be possible to support at least other primitive types, like Integer, Boolean?

Please see the failing spec here: #13

Hi,

I've added the gem and followed the instructions, but I keep getting this error: undefined method `start_with?' for #Pathname:0x00000006327430

Method called: YAML.ext_load_file('/opt/config/test.yml')

Any ideas?

Thanks.

Details:
undefined method `start_with?' for #Pathname:0x00000006327430

/usr/local/rvm/gems/ruby-1.9.3-p551/gems/yaml_extend-1.1.1/lib/yaml_extend.rb:160:in `absolute_path?'

/usr/local/rvm/gems/ruby-1.9.3-p551/gems/yaml_extend-1.1.1/lib/yaml_extend.rb:142:in `make_absolute_path'

/usr/local/rvm/gems/ruby-1.9.3-p551/gems/yaml_extend-1.1.1/lib/yaml_extend.rb:107:in `ext_load_file_recursive'

/usr/local/rvm/gems/ruby-1.9.3-p551/gems/yaml_extend-1.1.1/lib/yaml_extend.rb:75:in `ext_load_file'