Module: Flows::Util::InheritableSingletonVars::DupStrategy

Defined in:
lib/flows/util/inheritable_singleton_vars/dup_strategy.rb

Overview

Note:

If you change variables in a parent class after a child being defined it will have no effect on a child. Remember this when working in environments with tricky or experimental autoload mechanism.

Strategy which uses #dup to copy variables to a child class.

Can be applied several times to the same class.

Can be applied in the middle of inheritance chain.

When your value is a custom class you may need to adjust #dup behaviour. It can be done using initialize_dup method. Unfortunately it's not documented well in the standard library. So, this will help you.

See Also:

Since:

  • 0.4.0

Defined Under Namespace

Modules: InheritanceCallback

Constant Summary collapse

VAR_LIST_VAR_NAME =

Since:

  • 0.4.0

:@inheritable_vars_with_dup

Class Method Summary collapse

Class Method Details

.call(klass, attrs_with_default = {}) ⇒ Object

Note:

Variable names should look like :@var or '@var'.

Applies behaviour and defaults for singleton variables.

Examples:

class MyClass
  Flows::Util::InheritableSingletonVars::DupStrategy.call(
    self,
    :@my_list => []
  )
end

Parameters:

  • klass (Class) —

    target class.

  • attrs_with_default (Hash<Symbol, String => Object>) (defaults to: {}) —

    keys are variable names, values are default values.

Since:

  • 0.4.0



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# File 'lib/flows/util/inheritable_singleton_vars/dup_strategy.rb', line 66

def call(klass, attrs_with_default = {})
  init_variables_with_default_values(klass, attrs_with_default)

  var_names = attrs_with_default.keys.map(&:to_sym)
  add_var_list(klass, var_names)

  inject_inheritance_hook(klass)
end

.migrate(from_mod, to_mod) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Moves variables between modules

Since:

  • 0.4.0



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# File 'lib/flows/util/inheritable_singleton_vars/dup_strategy.rb', line 78

def migrate(from_mod, to_mod)
  var_list = from_mod.instance_variable_get(VAR_LIST_VAR_NAME)
  to_mod.instance_variable_set(VAR_LIST_VAR_NAME, var_list.dup)

  var_list.each do |name|
    to_mod.instance_variable_set(name, from_mod.instance_variable_get(name).dup)
  end
end