Output value of keys in hash by method in ruby - ruby

Question

I wrote weird, little and simple DSL on ruby, and I stuck on output values of keys.
I need to output values of concrete key of hash by that command:
p config.key1
#> Output down below:
#> "value1"
# here's key1 is key of hash, i want to output value of key that i wrote in method call.
# p config.key_name for example
There's my configus realisation:
require "deep_merge/rails_compat"
class Configus
class InHash
attr_reader :inner_hash
def initialize
#inner_hash = {}
end
def method_missing(name, *args, &block)
if block_given?
context = InHash.new
context.instance_eval &block
result = context.inner_hash
else
result = args
end
#inner_hash[name] = result
end
end
def self.config(environment, parent = nil, &block)
in_hash = InHash.new
in_hash.instance_eval &block
keys = in_hash.inner_hash.keys
index = keys.find_index(environment)
if parent && environment
parent_hash = in_hash.inner_hash[parent]
adopted_hash = in_hash.inner_hash[environment]
merged_hash = parent_hash.deeper_merge!(adopted_hash, { :overwrite_arrays => "TRUE" })
elsif environment == keys[index]
"#{environment.capitalize} hash: " + in_hash.inner_hash[environment]
end
end
end
Here's my init.rb:
require "./configus"
require "pry"
config = Configus.config :staging, :production do
production do
key1 "value1"
key2 "value2"
group1 do
key3 "value3"
key4 "value4"
end
end
staging do
key2 "new value2"
group1 do
key4 "new value4"
end
end
development do
key1 "new value1"
key2 "value2"
group1 do
key3 "new value3"
key4 "value4"
end
end
productionisgsgsd do
key10 "value10"
end
end
puts config.key1
#> I wrote output down below:
Traceback (most recent call last):
init.rb:35:in `<main>': undefined method `key1' for #<Hash:0x000056261379cdb0> (NoMethodError)
Did you mean? key
key?
keys
I just want to output value of concrete key of hash with concrete command:
p config.key_name
But i don't know how to do that and because of my stupid problem i want to ask you guys.
P.S Sorry for my english skill and that weird realisation of dsl ¯\_(ツ)_/¯

Answer 1

The issue is that you return a normal hash from your Configus.config method. Instead you should return your special InHash instance which you're able to customize behaviour.
The current issue lies here:
def self.config(environment, parent = nil, &block)
in_hash = InHash.new
in_hash.instance_eval &block
keys = in_hash.inner_hash.keys
index = keys.find_index(environment)
if parent && environment
parent_hash = in_hash.inner_hash[parent]
adopted_hash = in_hash.inner_hash[environment]
merged_hash = parent_hash.deeper_merge!(adopted_hash, { :overwrite_arrays => "TRUE" })
# ^ the above line returns a normal hash from the method
in_hash # <= add this to return your in_hash object
elsif environment == keys[index]
"#{environment.capitalize} hash: " + in_hash.inner_hash[environment]
end
end
The problem is not entirely solved with the above, since this now returns your InHash instance, but your InHash has no way of fetching keys, you can only set them. So you want to add a way to fetch values:
def method_missing(name, *args, &block)
if block_given?
context = InHash.new
context.instance_eval &block
#inner_hash[name] = context # set to the nested InHash instance
elsif args.empty?
#inner_hash[name] # without arguments given read the value
else
#inner_hash[name] = args # set to the arguments provided
end
end
The following code:
config = Configus.config :staging, :production do
# ...
end
Should now set config to an InHash instance, that has your custom behaviour defined. The args.empty? check in method_missing will return a value if no further arguments are given. Meaning that:
config.key1
Should now return your ["value1"] value. #inner_hash[name] = args will always set the value to an array. If you don't want this you might want to change it to:
#inner_hash[name] = args.size > 1 ? args : args.first