Lambda the Ultimate

ContextL is a CLOS extension for Context-oriented Programming. Currently, there is no documentation available, but you can find a small test case in the distribution and an introduction to ContextL's features in a first overview paper.

The paper says:

We present ContextL,a language extension for the Common Lisp Object System that allows for Context-oriented Programming. It provides means to associate partial class and method definitions with layers and to activate such layers in the control flow of a running program. When a layer is activated, the partial definitions become part of the program until this layer is deactivated. This has the effect that the behavior of a program can be modified according to the context of its use without the need to mention such context dependencies in the affected base program. We illustrate these ideas by describing a way to a)provide different UI views on the same object while b)keeping the conceptual simplicity of OOP that objects know themselves how to behave, in this case how to display themselves. These seemingly contradictory goals can be achieved by separating out class definitions into separate layers instead of separating out the display code into different classes.

Sounds kinda like AOP to me. It intriguings, anyway.

Rails is becoming the main reason people decide to pick up Ruby, which is something worth pondering. The interaction between a programming language and a very dominant framework, which isn't part of the standard library of language, is quite interesting.

Some quotes from the interview:

Rails is opinionated software. It eschews placing the old ideals of software in a primary position.

One characteristic of opinionated software is the notion of "conventions over configuration." If you follow basic conventions, such as classes are singular and tables are plural (a person class relates to a people table), you're rewarded by not having to configure that link. The class automatically knows which table to use for persistence. We have a ton of examples like that, which all add up to make a huge difference in daily use.

I really like our domain-specific languages. The beauty of specifying relationships with belongs_to, has_one, has_many and has_and_belongs_to_many. The ease of using validations like validates_presence_of :name.

I think Rails feels, smells, and tastes like it does exactly because its very Ruby-like. It plays heavily on the best in Ruby. The blocks, the ease of creating domain-specific languages, and so on.

What has happened, though, is that Active Record has reduced the pain of dealing with the object-relational mismatch to a point where its a lot less appealing to seek alternatives—especially with databases like SQLite that give you the feel of flat text files, but within the context of SQL.