README.md in qonfig-0.20.0 vs README.md in qonfig-0.21.0

@@ -40,10 +40,21 @@
   - [Inheritance](#inheritance)
   - [Composition](#composition)
   - [Hash representation](#hash-representation)
   - [Smart Mixin](#smart-mixin) (`Qonfig::Configurable`)
   - [Instantiation without class definition](#instantiation-without-class-definition) (`Qonfig::DataSet.build(&definitions)`)
+- [Compacted config](#compacted-config)
+  - [Definition and instantiation](#definition-and-instantiation)
+    - [by raw initialization](#by-raw-initialization)
+    - [by existing Qonfig::DataSet class](#by-existing-qonfigdataset-class)
+    - [by existing Qonfig::DataSet instance](#by-existing-qonfigdataset-instance)
+    - [instantiation without class definition](#instantiation-without-class-definition-1)
+    - [validation API](#validation-api-see-full-documentation)
+  - [Setting readers and writers](#setting-readers-and-writers)
+    - [reading](#reading-by-setting-name-and-index-method-with-dot-notation-support-and-indifferent-access)
+    - [writing](#writing-by-setting-name-and-index-method-with-dot-notation-support-and-indifferent-access)
+    - [precitaes](#predicates-see-full-documentation)
 - [Interaction](#interaction)
   - [Iteration over setting keys](#iteration-over-setting-keys) (`#each_setting`, `#deep_each_setting`)
   - [List of config keys](#list-of-config-keys) (`#keys`, `#root_keys`)
   - [Config reloading](#config-reloading) (reload config definitions and option values)
   - [Clear options](#clear-options) (set to `nil`)
@@ -51,10 +62,16 @@
   - [Settings as Predicates](#settings-as-predicates)
   - [Setting key existence](#setting-key-existence) (`#key?`/`#option?`/`#setting?`)
   - [Run arbitrary code with temporary settings](#run-arbitrary-code-with-temporary-settings) (`#with(configs = {}, &arbitrary_code)`)
 - [Import settings / Export settings](#import-settings--export-settings)
   - [Import config settings](#import-config-settings) (`as instance methods`)
+    - [Import a set of setting keys (simple dot-noated key list)](#import-a-set-of-setting-keys-simple-dot-noated-key-list)
+    - [Import with custom method names (mappings)](#import-with-custom-method-names-mappings)
+    - [Prexify method name](#prexify-method-name)
+    - [Import nested settings as raw Qonfig::Settings objects](#import-nested-settings-as-raw-qonfigsettings-objects)
+    - [Import with pattern-matching](#import-with-pattern-matching)
+    - [Support for predicate-like methods](#support-for-predicate-like-methods)
   - [Export config settings](#export-config-settings) (`as singleton methods`)
 - [Validation](#validation)
   - [Introduction](#introduction)
   - [Key search pattern](#key-search-pattern)
   - [Proc-based validation](#proc-based-validation)
@@ -62,18 +79,20 @@
   - [Predefined validations](#predefined-validations)
   - [Custom predefined validators](#custom-predefined-validators)
   - [Validation of potential setting values](#validation-of-potential-setting-values)
 - [Work with files](#work-with-files)
   - **Setting keys definition**
+    - `(DSL methods for dynamic setting keys definition by reading them from a file)`
     - [Load from YAML file](#load-from-yaml-file)
     - [Expose YAML](#expose-yaml) (`Rails`-like environment-based YAML configs)
     - [Load from JSON file](#load-from-json-file)
     - [Expose JSON](#expose-json) (`Rails`-like environment-based JSON configs)
     - [Load from ENV](#load-from-env)
     - [Load from \_\_END\_\_](#load-from-__end__) (aka `.load_from_self`)
     - [Expose \_\_END\_\_](#expose-__end__) (aka `.expose_self`)
   - **Setting values**
+    - `(instance methods for loading setting values from a file to existing config object with already defined setting keys)`
     - [Default setting values file](#default-setting-values-file)
     - [Load setting values from YAML file](#load-setting-values-from-yaml-file-by-instance)
     - [Load setting values from JSON file](#load-setting-values-from-json-file-by-instance)
     - [Load setting values from \_\_END\_\_](#load-setting-values-from-__end__-by-instance)
     - [Load setting values from file manually](#load-setting-values-from-file-manually-by-instance)
@@ -97,13 +116,13 @@
 
 ---
 
 ### Definition and Access
 
-- `setting(name, value)` - define setting with corresponding name and value;
-- `setting(name) { setting(name, value); ... }` - define nested settings OR reopen existing nested setting and define some new nested settings;
-- `re_setting(name, value)`, `re_setting(name) { ... }` - re-define existing setting (or define new if the original does not exist);
+- `setting(name, value = nil)` - define setting with corresponding name and value;
+- `setting(name) { setting(name, value = nil); ... }` - define nested settings OR reopen existing nested setting and define some new nested settings;
+- `re_setting(name, value = nil)`, `re_setting(name) { ... }` - re-define existing setting (or define new if the original does not exist);
 - accessing: [access via method](#access-via-method), [access via index-method \[\]](#access-via-index-method-),
   [.dig](#dig), [.slice](#slice), [.slice_value](#slice_value), [.subset](#subset);
 
 ```ruby
 # --- definition ---
@@ -597,10 +616,222 @@
 config.settings.web_api # => "api.google.com"
 ```
 
 ---
 
+## Compacted config
+
+- [Definition and instantiation](#definition-and-instantiation)
+  - [by raw initialization](#by-raw-initialization)
+  - [by existing Qonfig::DataSet class](#by-existing-qonfigdataset-class)
+  - [by existing Qonfig::DataSet instance](#by-existing-qonfigdataset-instance)
+  - [instantiation without class definition](#instantiation-without-class-definition-1)
+  - [validation API](#validation-api-see-full-documentation)
+- [Setting readers and writers](#setting-readers-and-writers)
+  - [reading](#reading-by-setting-name-and-index-method-with-dot-notation-support-and-indifferent-access)
+  - [writing](#writing-by-setting-name-and-index-method-with-dot-notation-support-and-indifferent-access)
+  - [precitaes](#predicates-see-full-documentation)
+
+---
+
+- `Qonfig::Compacted`: represents the compacted config object with setting readers and setting writers;
+- setting keys are represented as direct instace methods (`#settings` invokation does not need);
+- no any other useful instance-based functionality - just setting readers, setting writers and setting predicates:
+- support for index-like access methods (`[]`,`[]=`);
+- full support of `Qonfig::DataSet` definition DSL commands:
+  - `setting`, `re_setting` [doc](#definition-and-access)
+  - `validate`, `add_validator` [doc](#validation)
+  - `load_from_self` [doc](#load-from-__end__), `load_from_yaml` [doc](#load-from-yaml-file), `load_from_json` [doc](#load-from-json-file), `load_from_toml` [doc](#plugins-toml);
+  - `expose_self` [doc](#expose-__end__), `expose_yaml` [doc](#expose-yaml), `expose_json` [doc](#expose-json), `expose_toml` [doc](#plugins-toml)
+  - `values_file` [doc](#default-setting-values-file)
+- support for validation of potential setting values `.valid_with?` [documentation](#validation-of-potential-setting-values);
+- can be instantiated by:
+  - by existing config object: `Qonfig::DataSet#compacted` or `Qonfig::Compacted.build_from(config, &configuration)`;
+  - from existing `Qonfig::DataSet` class: ``Qonfig::DataSet.build_compacted`;
+  - by direct instantiation: `Qonfig::Compacted.new(settings_values = {}, &configuration)`;
+  - by implicit instance building without explicit class definition `Qonfig::Compacted.build(&dsl_commands) # => instance of Qonfig::Compacted`;
+- you can define your own instance methods too;
+
+---
+
+### Definition and instantiation
+
+#### by raw initialization
+
+```ruby
+class Config < Qonfig::Compacted
+  setting :api, 'google.com'
+  setting :enabled, true
+  setting :queue do
+    setting :engine, :sidekiq
+  end
+end
+
+config = Config.new(api: 'yandex.ru') do |conf|
+  conf.enabled = false
+end
+
+config.api # => 'yandex.ru'
+config.enabled # => false
+config.queue.engine # => :sidekiq
+```
+
+#### by existing Qonfig::DataSet class
+
+```ruby
+class Config < Qonfig::DataSet
+  setting :api, 'google.com'
+  setting :enabled, true
+end
+
+config = Config.build_compacted # builds Qonfig::Compacted instance
+
+config.api # => 'google.com'
+config.enabled # => true
+```
+
+#### by existing Qonfig::DataSet instance
+
+- `Qonfig::DataSet#compacted`
+- (or) `Qonfig::Compacted.build_from(config)`
+
+```ruby
+class Config < Qonfig::DataSet
+  setting :api, 'google.com'
+  setting :enabled, true
+end
+
+config = Config.new
+
+compacted_config = config.compacted
+# --- or ---
+compacted_config = Qonfig::Compacted.build_from(config)
+
+compacted_config.api # => 'google.com'
+compacted_config.enabled # => true
+```
+
+#### instantiation without class definition
+
+```ruby
+config = Qonfig::Compacted.build do
+  setting :api, 'google.ru'
+  setting :enabled, true
+end
+
+config.api # => 'google.ru'
+config.enabled # => true
+```
+
+#### validation API (see [full documentation](#validation)):
+
+```ruby
+# custom validators
+Qonfig::Compacted.define_validator(:version_check) do |value|
+  value.is_a?(Integer) && value < 100
+end
+
+class Config < Qonfig::Compacted
+  setting :api, 'google.ru'
+  setting :enabled, true
+  setting :version, 2
+  setting :queue { setting :engine, :sidekiq }
+
+  # full support of original validation api
+  validate :api, :string, strict: true
+  validate :enabled, :boolean, strict: true
+  validate :version, :version_check # custom validator
+  validate 'queue.#', :symbol
+end
+
+# potential values validation
+Config.valid_with?(api: :yandex) # => false
+Config.valid_with?(enabled: nil) # => false
+Config.valid_with?(version: nil) # => false
+Config.valid_with?(api: 'yandex.ru', enabled: false, version: 3) # => true
+
+config = Config.new
+
+# instance validation
+config.api = :yandex # => Qonfig::ValidationError (should be a type of string)
+config.version = nil # => Qonfig::ValidationError (can not be nil)
+config.queue.engine = 'sneakers' # => Qonfig::ValidationError (should be a type of symbol)
+```
+
+---
+
+### Setting readers and writers
+
+```ruby
+class Config < Qonfig::Compcated
+  setting :api, 'google.ru'
+  setting :enabled, true
+  setting :queue do
+    setting :engine, :sidekiq
+    setting :workers_count, 10
+  end
+end
+
+config = Config.new
+```
+
+#### reading (by setting name and index method with dot-notation support and indifferent access)
+
+```ruby
+# by setting name
+config.api # => 'google.ru'
+config.enabled # => true
+config.queue.engine # => :sidekiq
+config.queue.workers_count # => 10
+
+# by index method with dot-notation support and indiffernt access
+config[:api] # => 'google.ru'
+config['enabled'] # => true
+config[:queue][:engine] # => :sidekiq
+config['queue.workers_count'] # => 10
+```
+
+#### writing (by setting name and index method with dot-notation support and indifferent access)
+
+```ruby
+# by setting name
+config.api = 'yandex.ru'
+config.queue.engine = :sidekiq
+# and etc
+
+# by index method with dot-notaiton support and indifferent access
+config['api'] = 'yandex.ru'
+config['queue.engine'] = :sidekiq
+config[:queue][:workers_count] = 5
+```
+
+#### predicates ([see full documentation](#settings-as-predicates))
+
+```ruby
+class Config < Qonfig::Compcated
+  setting :enabled, true
+  setting :api, 'yandex.ru'
+  setting :queue do
+    setting :engine, :sidekiq
+  end
+end
+
+config = Config.new
+
+config.enabled? # => true
+config.enabled = nil
+config.enabled? # => false
+
+config.queue.engine? # => true
+config.queue.engine =  nil
+config.queue.engine? # => false
+
+config.queue? # => true
+```
+
+---
+
 ## Interaction
 
 - [Iteration over setting keys](#iteration-over-setting-keys) (`#each_setting`, `#deep_each_setting`)
 - [List of config keys](#list-of-config-keys) (`#keys`, `#root_keys`)
 - [Config reloading](#config-reloading) (reload config definitions and option values)
@@ -1055,19 +1286,22 @@
 ### Import config settings
 
 - `Qonfig::Imports` - a special mixin that provides the convenient DSL to work with config import features (`.import_settings` method);
 - `.import_settings` - DSL method for importing configuration settings (from a config instance) as instance methods of a class;
 - (**IMPORTANT**) `import_settings` imports config settings as access methods to config's settings (creates `attr_reader`s for your config);
+- generated methods can be used as predicates (with trailing `?` symbol);
+- you can generate `attr_accessor`s by specifying `accessor: true` option
+  (be careful: you can get `Qonfig::AmbiguousSettingValueError` when you try to assign a value to config option which have nested settings);
 - signature: `.import_settings(config_object, *setting_keys, mappings: {}, prefix: '', raw: false)`
   - `config_object` - an instance of `Qonfig::DataSet` whose config settings should be imported;
   - `*setting_keys` - an array of dot-notaed config's setting keys that should be imported
     (dot-notaed key is a key that describes each part of nested setting key as a string separated by `dot`-symbol);
     - last part of dot-notated key will become a name of the setting access instance method;
   - `mappings:` - a map of keys that describes custom method names for each imported setting;
   - `prefix:` - prexifies setting access method name with custom prefix;
   - `raw:` - use nested settings as objects or hashify them (`false` by default (means "hashify nested settings"));
-
+  - `accessor:` - generate `attr_accessor` for imported config settigns (`false` by default (means "generate `attr_reader`s only"));
 ---
 
 Suppose we have a config with deeply nested keys:
 
 ```ruby
@@ -1086,10 +1320,17 @@
 end
 ```
 
 Let's see what we can to do :)
 
+- [Import a set of setting keys (simple dot-noated key list)](#import-a-set-of-setting-keys-simple-dot-noated-key-list)
+- [Import with custom method names (mappings)](#import-with-custom-method-names-mappings)
+- [Prexify method name](#prexify-method-name)
+- [Import nested settings as raw Qonfig::Settings objects](#import-nested-settings-as-raw-qonfigsettings-objects)
+- [Import with pattern-matching](#import-with-pattern-matching)
+- [Support for predicate-like methods](#support-for-predicate-like-methods)
+
 #### Import a set of setting keys (simple dot-noated key list)
 
 - last part of dot-notated key will become a name of the setting access instance method;
 
 ```ruby
@@ -1143,14 +1384,34 @@
   )
 end
 
 service = ServiceObject.new
 
-service.config_credentials # => { login" => "D@iVeR", "auth_token" => "IAdkoa0@()1239uA" }
+service.config_account # => { login" => "D@iVeR", "auth_token" => "IAdkoa0@()1239uA" }
 service.config_secret_token # => "IAdkoa0@()1239uA"
 ```
 
+#### Support for predicate-like methods
+
+- generated methods can be used as predicates (with trailing `?` symbol);
+
+```ruby
+class ServiceObject
+  include Qonfig::Imports
+
+  import_settings(AppConfig,
+    'web_api.credentials.account',
+    mappings: { secret_token: 'web_api.credentials.account.auth_token' },
+  )
+end
+
+service = ServiceObject.new
+
+service.account? # => true
+service.secret_token? # => true
+```
+
 #### Import nested settings as raw Qonfig::Settings objects
 
 - `raw: false` is used by default (hashify nested settings)
 
 ```ruby
@@ -1179,11 +1440,11 @@
 service = ServiceObject.new
 
 service.credentials # => { "account" => { "login" => "D@iVeR", "auth_token" => "IAdkoa0@()1239uA"} }
 ```
 
-#### Immport with pattern-matching
+#### Import with pattern-matching
 
 - import root keys only: `import_settings(config_object, '*')`;
 - import all keys: `import_settings(config_object, '#')`;
 - import the subset of keys: `import_settings(config_object, 'group.*.group.#')` (pattern-mathcing usage);
 
@@ -1209,11 +1470,11 @@
   # generated instance methods:
   #   => service.web_api
   #   => service.graphql_api
 
   # import ALL keys
-  import_Settings(AppConfig, '#')
+  import_settings(AppConfig, '#')
   # generated instance methods:
   #   => service.web_api
   #   => service.credentials
   #   => service.account
   #   => service.login
@@ -1224,21 +1485,25 @@
 
 ---
 
 ### Export config settings
 
+- works in `.import_settings` manner [doc](#import-config-settings) (see examples and documentation above `:)`)
 - all config objects can export their settings to an arbitrary object as singleton methods;
 - (**IMPORTANT**) `export_settings` exports config settings as access methods to config's settings (creates `attr_reader`s for your config);
+- generated methods can be used as predicates (with trailing `?` symbol);
+- you can generate `attr_accessor`s by specifying `accessor: true` option
+  (be careful: you can get `Qonfig::AmbiguousSettingValueError` when you try to assign a value to config option which have nested settings);
 - signature: `#export_settings(exportable_object, *setting_keys, mappings: {}, prefix: '', raw: false)`:
   - `exportable_object` - an arbitrary object for exporting;
   - `*setting_keys` - an array of dot-notaed config's setting keys that should be exported
     (dot-notaed key is a key that describes each part of nested setting key as a string separated by `dot`-symbol);
     - last part of dot-notated key will become a name of the setting access instance method;
   - `mappings:` - a map of keys that describes custom method names for each exported setting;
   - `prefix:` - prexifies setting access method name with custom prefix;
   - `raw:` - use nested settings as objects or hashify them (`false` by default (means "hashify nested settings"));
-- works in `.import_settings` manner [doc](#import-config-settings) (see examples and documentation above `:)`)
+ - `accessor:` - generate `attr_accessor` for imported config settigns (`false` by default (means "generate `attr_reader`s only"));
 
 ```ruby
 class Config < Qonfig::DataSet
   setting :web_api do
     setting :credentials do
@@ -1256,23 +1521,35 @@
 
 config = Config.new
 service = ServiceObject.new
 
 service.config_account # => NoMethodError
+```
 
+```ruby
 # NOTE: export settings as access methods to config's settings
 config.export_settings(service, 'web_api.credentials.account', prefix: 'config_')
 
 service.config_account # => { "login" => "D@iVeR", "auth_token" => "IAdkoa0@()1239uA" }
+```
 
+```ruby
 # NOTE: export settings with pattern matching
 config.export_settings(service, '*') # export root settings
 
 service.web_api # => { 'credentials' => { 'account' => { ... } }, 'graphql_api' => false }
 service.graphql_api # => false
 ```
 
+```ruby
+# NOTE: predicates
+config.export_settings(service, '*')
+
+config.web_api? # => true
+config.graphql_api? # => false
+```
+
 ---
 
 ## Validation
 
 - [Introduction](#introduction)
@@ -1571,15 +1848,16 @@
   # NOTE: definition
   define_validator(:user_type) { |value| value.is_a?(User) }
 
   setting :admin # some key
 
-  validate :admin, :user_type # NOTE: useage
+  # NOTE: usage
+  validate :admin, :user_type
 end
 ```
 
-#### Defin new global validator
+#### Define new global validator
 
 ```ruby
 Qonfig::DataSet.define_validator(:secured_value) do |value|
   value == '***'
 end
@@ -1617,12 +1895,12 @@
 
 ---
 
 ### Validation of potential setting values
 
-- (**instance-level**) `#valid_with?(configurations = {})` - check that current config instalce will be valid with passed configurations;
-- (**class-level**) `.valid_with?(configurations = {})` - check that potential config instancess will be valid with passed configurations;
+- (**instance-level**) `#valid_with?(setting_values = {}, &configuration)` - check that current config instalce will be valid with passed configurations;
+- (**class-level**) `.valid_with?(setting_values = {}, &configuration)` - check that potential config instancess will be valid with passed configurations;
 - makes no assignments;
 
 #### #valid_with? (instance-level)
 
 ```ruby
@@ -1639,10 +1917,16 @@
 config = Config.new
 
 config.valid_with?(enabled: true, queue: { adapter: 'que' }) # => true
 config.valid_with?(enabled: 123) # => false (should be a type of boolean)
 config.valid_with?(enabled: true, queue: { adapter: Sidekiq }) # => false (queue.adapter should be a type of string)
+
+# do-config notation is supported too
+config.valid_with?(enabled: true) do |conf|
+  conf.queue.adapter = :sidekiq
+end
+# => false (queue.adapter should be a type of string)
 ```
 
 #### .valid_with? (class-level)
 
 ```ruby
@@ -1657,10 +1941,16 @@
 end
 
 Config.valid_with?(enabled: true, queue: { adapter: 'que' }) # => true
 Config.valid_with?(enabled: 123) # => false (should be a type of boolean)
 Config.valid_with?(enabled: true, queue: { adapter: Sidekiq }) # => false (queue.adapter should be a type of string)
+
+# do-config notation is supported too
+Config.valid_with?(enabled: true) do |config|
+  config.queue.adapter = :sidekiq
+end
+# => false (queue.adapter should be a type of string)
 ```
 
 ---
 
 ## Work with files
@@ -2115,17 +2405,18 @@
 
 ### Load from \_\_END\_\_
 
 - aka `load_from_self`
 - `:format` - specify the format of data placed under the `__END__` instruction:
-  - `format: :yaml` - **YAML** format (by default);
+  - `format: :dynamic` (default) - automatic format resolvation;
+  - `format: :yaml` - **YAML** format;
   - `format: :json` - **JSON** format;
   - `format: :toml` - **TOML** format (via `toml`-plugin);
 
 ```ruby
 class Config < Qonfig::DataSet
-  load_from_self # on the root (format: :yaml is used by default)
+  load_from_self # on the root (:dynamic format is used by default)
 
   setting :nested do
     load_from_self, format: :yaml # with explicitly identified YAML format
   end
 end
@@ -2162,11 +2453,12 @@
 
 - aka `expose_self`;
 - works in `expose_json` and `expose_yaml` manner, but with `__END__` instruction of the current file;
 - `env:` - your environment name (must be a type of `String`, `Symbol` or `Numeric`);
 - `:format` - specify the format of data placed under the `__END__` instruction:
-  - `format: :yaml` - **YAML** format (by default);
+  - `format: :dynamic` (default) - automatic format resolvation;
+  - `format: :yaml` - **YAML** format;
   - `format: :json` - **JSON** format;
   - `format: :toml` - **TOML** format (via `toml`-plugin);
 
 ```ruby
 class Config < Qonfig::DataSet
@@ -2331,14 +2623,15 @@
 ---
 
 ### Load setting values from YAML file (by instance)
 
 - prvoides an ability to load predefined setting values from a yaml file;
-- `#load_from_yaml(file_path, strict: true, expose: nil)`
+- `#load_from_yaml(file_path, strict: true, expose: nil, &configurations)`
   - `file_path` - full file path or `:self` (`:self` means "load setting values from __END__ data");
   - `:strict` - rerquires that file (or __END__-data) should exist (`true` by default);
   - `:expose` - what the environment-based subset of keys should be used (`nil` means "do not use any subset of keys") (`nil` by default);
+  - `&configurations` - `do |config|` ability :)
 
 #### Default behavior
 
 ```yaml
 # config.yml
@@ -2429,14 +2722,15 @@
 ---
 
 ### Load setting values from JSON file (by instance)
 
 - prvoides an ability to load predefined setting values from a json file;
-- `#load_from_yaml(file_path, strict: true, expose: nil)`
+- `#load_from_json(file_path, strict: true, expose: nil, &configurations)`
   - `file_path` - full file path or `:self` (`:self` means "load setting values from __END__ data");
   - `:strict` - rerquires that file (or __END__-data) should exist (`true` by default);
   - `:expose` - what the environment-based subset of keys should be used (`nil` means "do not use any subset of keys") (`nil` by default);
+  - `&configurations` - `do |config|` ability :)
 
 #### Default behavior
 
 ```json
 // config.json
@@ -2537,15 +2831,16 @@
 ---
 
 ### Load setting values from \_\_END\_\_ (by instance)
 
 - prvoides an ability to load predefined setting values from `__END__` file section;
-- `#load_from_self(strict: true, expose: nil)`
+- `#load_from_self(strict: true, expose: nil, &configurations)`
   - `:format` - defines the format of file (`:dynamic` means "try to automatically infer the file format") (`:dynamic` by default);
     - supports `:yaml`, `:json`, `:toml` (via `Qonfig.plugin(:toml)`), `:dynamic` (automatic format detection);
   - `:strict` - requires that __END__-data should exist (`true` by default);
   - `:expose` - what the environment-based subset of keys should be used (`nil` means "do not use any subset of keys") (`nil` by default);
+  - `&configurations` - `do |config|` ability :)
 
 #### Default behavior
 
 ```ruby
 class Config < Qonfig::DataSet
@@ -2625,16 +2920,17 @@
 
 ### Load setting values from file manually (by instance)
 
 - prvoides an ability to load predefined setting values from a file;
 - works in instance-based `#load_from_yaml` / `#load_from_json` / `#load_from_self` manner;
-- signature: `#load_from_file(file_path, format: :dynamic, strict: true, expose: nil)`:
+- signature: `#load_from_file(file_path, format: :dynamic, strict: true, expose: nil, &configurations)`:
   - `file_path` - full file path or `:self` (`:self` means "load setting values from __END__ data");
   - `:format` - defines the format of file (`:dynamic` means "try to automatically infer the file format") (`:dynamic` by default);
     - supports `:yaml`, `:json`, `:toml` (via `Qonfig.plugin(:toml)`), `:dynamic` (automatic format detection);
   - `:strict` - rerquires that file (or __END__-data) should exist (`true` by default);
   - `:expose` - what the environment-based subset of keys should be used (`nil` means "do not use any subset of keys") (`nil` by default);
+  - `&configurations` - `do |config|` ability :)
 - see examples for instance-based `#load_from_yaml` ([doc](#load-setting-values-from-yaml-by-instance)) / `#load_from_json` ([doc](#load-setting-values-from-json-by-instance)) / `#load_from_self` ([doc](#load-setting-values-from-__end__-by-instance));
 
 ---
 
 ### Save to JSON file
@@ -2816,12 +3112,13 @@
 
 ---
 
 ### Plugins: toml
 
+- `Qonfig.plugin(:toml)`
 - adds support for `toml` format ([specification](https://github.com/toml-lang/toml));
-- depends on `toml-rb` gem ([link](https://github.com/emancu/toml-rb));
-- supports TOML `0.5.0` format (dependency lock);
+- depends on `toml-rb` gem ([link](https://github.com/emancu/toml-rb)) (tested on `>= 2.0`);
+- supports TOML `0.5.0` format (dependency lock) (`toml-rb >= 2.0`);
 - provides `.load_from_toml` (works in `.load_from_yaml` manner ([doc](#load-from-yaml-file)));
 - provides `.expose_toml` (works in `.expose_yaml` manner ([doc](#expose-yaml)));
 - provides `#save_to_toml` (works in `#save_to_yaml` manner ([doc](#save-to-yaml-file))) (`toml-rb` has no native options);
 - provides `format: :toml` for `.values_file` ([doc]());
 - provides `#load_from_toml` (work in `#load_from_yaml` manner ([doc](#load-setting-values-from-yaml)));