__python_tricks__

[wtd]

In Python, you can add all kinds of interesting behavior to your classes by defining functions with names like __call__.

code:

>>> class A(object): ...    def __call__(self): ...       print 42 ... >>> a = A() >>> a() 42 >>>

How many of these do you know of?

[Null]

Very well known, but there is also __str__()

code:

class Person(object):     def __init__(self, name, age):         self.name = name         self.age = age     def __str__(self):         return "%s is %s years old" % (self.name, self.age) person = Person("Joe", 263) print person

[wtd]

Null wrote:

Very well known, but there is also __str__()

I see your __str__ and raise you a __repr__.

code:

>>> class A(object): ...    def __repr__(self): ...       return "Hello world" ... >>> A() Hello world >>>

[Null]

__iter__() and __len__()

code:

class LinkedList(object):     class Node(object):         def __init__(self, data):             self.data = data             self.next = None     def __init__(self, data_list):         self.first = self.Node(data_list[0])         self.__size = 0         self.current = self.first                 for data in data_list[2:]:             self.append(data)     def last(self):         current = self.first         while current.next is not None:             current = current.next         return current     def append(self, data):         self.__size += 1                 self.last().next = self.Node(data)     def __len__(self):         return self.__size     def __iter__(self):         return self     def next(self):         try:             if not self.current:                 raise StopIteration             result = self.current.data             self.current = self.current.next             return result         except StopIteration:             self.current = self.first             raise StopIteration if __name__ == "__main__":     linked_list = LinkedList(range(1, 11))     for node in linked_list:         print node

I love Ruby, I really do. Its consistency, blocks, and pure design. My problem with it is that obscure-ness (is that a word?) in code seems to be preferred, and it starts to look extremely cryptic. I'm starting to lean towards Python, especially when it comes to readability. I'm still deciding which I prefer.

[rizzix]

One of the reasons I dont like python is because of these special __methods__. What an ugly naming convention.

[Cervantes]

They don't look so bad. They are effective at drawing your attention to them. And so your attention should be drawn to them, as they are special.

[rizzix]

I would hardly call __str__, __len__, __iter__, etc, special.

Instead of __init__ they could have simply defined a method called self. Since "self" is used to refer to "this" object, having a method my the name self can safely act as a constructor for "this" object.

(basically lots of things can be done a lot better without the ugly convention)

[McKenzie]

So you like using compareTo in Java?
Try __lt__(self, other) in Python. Called when < is used.
I like this because I miss the good old operator overloading from C.

[wtd]

McKenzie wrote:

I like this because I miss the good old operator overloading from C.

I hope you mean C++.

[McKenzie]

, I actually typed C on purpose. I didn't think about it that much. I recalled learning about operator overloading about 12-14 years ago. I didn't do much C++ back then, so I assumed this was C knowledge.

[wtd]

No problem. The compatibilities between the two have made it really hard to push the idea that they're distinct languages.