Ever wonder why Python's
unicode types lack obvious length
methods? Yes, we can get the length via the special
but instead as Python developers we get the so-called 'luxury' of
discovering length via the Python's built-in
len() function. So
instead of calling the length of objects the way Rubyists or
>> # ruby >> s = "Hello, World!" => "Hello, World!" >> s.length 13
...as Python developers we suffer through it like this:
>>> # python >>> s = "Hello, World!" >>> len(s) 13 >>> s.__len__() # This is what len() calls to get the length 13
I'm sure Python luminaries like Guido Van Rossum, Alex Gaynor, David Beazley, and Raymond Hettiger can explain why Python works this way. Their opinions are probably full of logic, history, and grand reasoning.
None of that applies to this blog post.
Clearly, it's time for Python to catch up with the other hip dynamic languages. Therefore, after years of careful study, I give you a Fixed String class.
class String(str): """ Adding critically unimportant functionality to Python's str type """ def len(self): return self.__len__()
As you can see it improves on Python's
str type by adding a built-in
len() method. Total success!
Now that I've fixed things in Python by creating the
property/attribute/method/thingee that even my
String class lacks.
including a handy
size method that serves as an alias for it's own
Fortunately, I come armed with the knowledge of how to use Python's
class String(str): """ Adding critically unimportant functionality to Python's str type """ def len(self): return self.__len__() @property def length(self): return self.len() @property def size(self): return self.length
Bam! Python is now equal to Ruby!
It's time for Python to take the lead. We've suffered for too long as second class citizens in terms of string length discovery. Let's add some more utility methods to our String class:
class String(str): """ Adding critically unimportant functionality to Python's str type """ def len(self): return self.__len__() @property def length(self): return self.len() @property def size(self): return self.length @property def width(self): return self.length @property def height(self): return self.length @property def area(self): return self.height * self.width
Boom! Python now dominates with invaluable properties that provide developers with the width, height, and area of a string. And to think I'm just getting started...
So far I've carefully changed the Python ecosystem with my brilliant addition to the language. What if I want to get stupidly dangerous? What if I want to allow developers the dangerous capability to alter the returned length of a String? Fortunately for me, and unfortunately for anyone who uses this code on a real project, I know how to be this stupidly dangerous.
I present to you the
import math class ConqueringString(String): """ Adding stupidly dangerous functionality to Python's str type """ def __init__(self, text): super(ConqueringString, self).__init__(text) self._length = self.__len__() def __len__(self): try: return self._length except AttributeError: return super(ConqueringString, self).__len__() def len(self, value=None): if value is None: return self._length self._length = value @property def length(self): return self.len() @length.setter def length(self, value): self._length = value @property def size(self): return self.length @size.setter def size(self, value): self.length = value @property def area(self): return self.height * self.width @area.setter def area(self, value): self.length = math.sqrt(value)
Does it work?
if __name__ == "__main__": s = ConqueringString("Hello, World!") print(s) print(s.length) s.length = 5 print(s.length) print(s.area) s.area = 50 print(s.area) print(len(s)) print(s[5:10]) # slicing still works! print(s.upper()) # other methods still work!
Run it and see. Or grab it off PyPI with
pip install stringtheory.
pip install stringtheory!
We can implement this power using Python lists, tuples, dictionaries, and everything else we can imagine. Let's do it!
This was my 2013 April Fool's Joke.
However, the code was a lot of fun to write and after Mike Bayer's
__new__ and a number of serious questions that people
emailed me yesterday, I plan to follow this post with some more
discussion on how to expand on native types in Python.
Published: 2013-4-01 00:01
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