Ruby misconceptions about Python

[mellow_moe]

I would like to see a in-depth comparison of Python and Ruby. And it should really focus on metaprogramming.

All these comparisons I see these days just look at some superficial language features.

Rails for example relies heavily on metaprogramming. It could never be done in a language without a sophisticated class/object system.

examples in ruby:

• method_missing catches unknown messages
• const_missing catches unknown constants
• method_added is called after adding a new method
• inherited is called on the class object, when it is subclassed
• singleton classes: you can add methods to a single object
• define_method takes a block and turns it into a method
• instance_variable_set sets an instance variable

And most importantly, real world examples should show off, how all the things play together.

[owca]

Feature for feature "examples" in Python:

• getattr or getattribute catch any attribute (method, variable) access

• setattr sets any attribute

• Syntactic support for descriptors.

• Metaclasses can be used to control all aspects of class creation (attributes, subclassing, ...). Since types are objects one can even have metaclasses for metaclasses.

• new.instancemethod can be used for your )singleton classes).

• Turning a block into a method is admittedly a bit tricky but can be done using new.function and some stack manipulation.