If monkey patching is permitted in both Ruby and Python, why is it more controversial in Ruby?

Question

In many discussions I have heard about Ruby in which people have expressed their reservations about the language, the issue of monkey patching comes up as one of their primary c

Answer 1

As a Python programmer who has had a taste of Ruby (and likes it), I think there is somewhat of an ironic parallel to when Python was beginning to become popular.

C and Java programmers would ‘bash’ Python, stating that it wasn't a real language, and that the dynamic nature of its types would be dangerous, and allow people to create ‘bad’ code. As Python became more popular, and the advantages of its rapid development time became apparent, not to mention the less verbose syntax:

// Java
Person p = new Person();

# Python
p = Person()

we began to see some more dynamic features appear in later versions of Java. Autoboxing and -unboxing make it less troublesome to deal with primitives, and Generics allow us to code once and apply it to many types.

It was with some amusement that I saw one of the key flexible features of Ruby – Monkey Patching, being touted as dangerous by the Python crowd. Having started teaching Ruby to students this year, I think that being able to ‘fix’ the implementation of an existing class, even one that is part of the system, is very powerful.

Sure, you can screw up badly and your program can crash. I can segfault in C pretty easily, too. And Java apps can die flaming death.

The truth is, I see Monkey Patching as the next step in dynamic and meta-programming. Funny, since it has been around since Smalltalk.