For some reason the direct manipulation of instance variables in Ruby has bothered me for a long time. But not until I read more about Smalltalk did I quite appreciate why that was. Compared to directly reading from or writing to the instance variables, using getters and setters also inside the class feels a lot cleaner, at least to me. Alas one doesn't always want to expose the methods generated by attr_* to the outside world, so I found myself repeatedly writing code similar to this:
attr_accessor :foo private :foo=
While it certainly gets the job done, it's a bit cumbersome in the long run, so I decided to write this gem as an alternative to the available attr_* methods.
A conflicted relationship with instance variables and Ruby 2.0+.
ivar_encapsulation can be installed via RubyGems.
$ gem install ivar_encapsulation
It only works on 2.0+ and I generally only test it with the most current Ruby release.
The most simple case is defining a purely internal attribute (both the getter and setter will be private):
class Foo attribute :foo end
Of course this also works for several attributes at the same time:
attribute :foo, :bar, :baz
For the grammatically anal like yours truly, attribute is aliased to attributes, so the above could also be written thus:
attributes :foo, :bar, :baz
Now for a more interesting use case:
attribute foo, getter: true
This will define an attribute with a public getter method (foo), while the setter (foo=) remains private. Essentially this is the same as doing the following:
attr_accessor :foo private :foo=
Once again this works for several attributes at the same time:
attribute :foo, :bar, :baz, getter: true
For completeness' sake, you can also define a private getter and a public setter, although I don't think I ever needed this specific case:
attribute :foo, setter: true
Last but not least there's the option to have both the getter and the setter as public methods, which is essentially the same as attr_accessor, although in a more explicit fashion. If you bother to use this gem at all, you probably want to define all your attributes in a consistent fashion:
attribute :foo, getter: true, setter: true
This is how your class definitions will look when using this gem:
class Foo attributes :foo, :bar # private getters and setters attribute :read_only, getter: true # public getter, private setter attribute :full_access, getter: true, setter: true # public getter and setter def initialize(foo) self.foo = foo ... end ... end
Being able to supply getters and setters as procs?
This project was created by Michael Kohl. He can be reached via email at citizen428 at gmail.com.
Copyright © 2013 Michael Kohl
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