Welcome to the Factory!
Overview
The Factory mixin provides a robust Factory implementation. Overrides are automatically registered upon sub-classing. Manual override and disables are available if auto-registration does not result in the desired factory overrides. Manual overrides are available at the class and global granularities. Method arguments can be passed in as strings or symbols so that overrides can be set even before classes have been defined.
Usage
Using the Factory
The Factory module should be included in the classes which you want to provide factory overrides.
class ParentClass
include Factory
def initialize arg=nil
@arg = arg
end
end
Inheriting from this class will automatically register the sub-class as the override of the parent class.
class Child1 < ParentClass
end
Sub-classes need not include Factory
though doing so should not hurt anything.
The create
class method is implemeted by the mixin for the parent class and all sub-classes. Constructor arguments can be passed similarly through create
.
ParentClass.create('hello') # Returns an object of type Child1
Subsequent sub-classing updates the factory overrides.
class Child2 < Child1
end
ParentClass.create # Returns an object of type Child2
Child1.create # Returns an object of type Child2
ParentClass.new # Works normally. Returns an object of type ParentClass.
class Child3 < ParentClass
end
ParentClass.create # Returns an object of type Child3
Child1.create # Returns an object of type Child2 since Child3 is not a decendent.
Manual Factory Overrides
If the resulting factory overrides are not what is desired, they can be manually overriden.
The methods that are discussed in the section takes arguments which are the class constants
Factory.global_disable_override Child3
or as a symbol (strings are also accepted).
Factory.global_disable_override :Child3
This allows overrides to be used even before a class is defined.
Factory Override Disable
Continuing from the above example ParentClass
has a factory override of Child3
since it was the last sub-class to inherit from it. If the intention is to have Child2
be the factory override there are several ways this can be accomplished.
To disable a class from overriding a particular class either of the following can be used.
Factory.disable_override ParentClass, Child3
ParentClass.create # Returns an object of type Child2
or,
ParentClass.disable_factory_override Child3
ParentClass.create # Returns an object of type Child2
Since the disable is with respect to a specific ancestor, other ancestors are uneffected.
Factory Override Enable
Another way of manually configuring overrides is through enabling an override. This can also be used to cancel an existing class specific factory disable override.
Factory.enable_override ParentClass, Child3
ParentClass.create # Returns an object of type Child3
The last override enable takes presedence.
Factory.enable_override ParentClass, Child2
ParentClass.create # Returns an object of type Child2
or,
ParentClass.enable_override Child2
ParentClass.create # Returns an object of type Child2
Subsequent calls of the disable override methods will cancel the previous enable overrides on the same types.
Global Factory Override Methods
To disable a class from overriding any classes use the following,
Factory.global_disable_override Child3
To cancel the disable override,
Factory.remove_global_disable_override Child3