python adding new methods to built-in types

Question

How would I go about writing python functions that can be append to strings (or other object)?

for example:

"FOO".lower()

How do they receive input? Are they generators?

I will happily read up on it, but I don't really know what I am looking for.

It is a [method](http://en.wikipedia.org/wiki/Method_(computer_programming)) — DrTyrsa, Mar 20 '12 at 10:35

score 6 · Accepted Answer · edited May 23 '17 at 10:08

6

Strings are objects and thus have methods. lower() is one of them.

You cannot add a custom method to str, unicode or any other builtin (written in C) classes - see Implementing a custom string method and Extending builtin classes in python

edited May 23 '17 at 10:08

Community

answered Mar 20 '12 at 10:36

ThiefMaster

thanks... I feel really stupid now, completely forgot that str was it's own class! make's far more sense! – beoliver Mar 20 '12 at 10:46

score 2 · Answer 2 · answered Mar 20 '12 at 10:39

They are not generators. They are simply methods defined on the string class.

You could create your own like this:

>>> class MyString(str):
...   def reversed(self):
...     return self[::-1]
... 
>>> x = MyString('spam and eggs')
>>> x.reversed()
'sgge dna maps'

2 Answers2