The Symbol Decoration gem provides symbol method extensions to implement DSL such as like where(:field.in => [1,2,3]).

The goal is to allow different ORMs such as Mongoid and NoBrainer to co-exist as both ORMs need such functionality.

In the following example: where(:field.in => [1,2,3]), the in keyword is a decorator, and decorates the :field symbol.

To register decorators, you may call Symbol::Decoration.register(decorator, ...). For example:

Symbol::Decoration.register(:in)
Symbol::Decoration.register(*%w(in nin eq ne not gt ge gte lt le lte))

Once registered, a decorator can be used with symbol.decorator, which returns a Symbol::Decoration instance.

To support the lowest common denominator, decorators may accept arguments and blocks. For example, :field.gt(5) is valid.

You may retrieve the decoration properties with:

• decorated_symbol.symbol to get the symbol which is being decorated.
• decorated_symbol.decorator to get the decoration (for example :gt).
• decorated_symbol.args to get the decoration arguments.
• decorated_symbol.blocks to get the decoration block.

Full example:

Symbol::Decoration.register(:gt)

:field.gt.is_a?(Symbol::Decoration) == true
:field.gt.symbol                    == :field
:field.gt.decorator                 == :gt
:field.gt(5).args                   == [5]
:field.gt { 5 }.block.call          == 5

To allow certain decorators to be chainable, you must use the :chainable => true option when registering the decorator. Example:

Symbol::Decoration.register(:any, chainable => true)
Symbol::Decoration.register(:in)

:field.any.in # valid
:field.in.any # invalid

Symbol Decoration is MIT Licensed.