How do I alias member functions in Python?

No problemo! You can alias a method, but you have to know how to use it:

>>> r=str.replace
>>> a='hello'
>>> r(r(r(r(a,'h','j'),'e','i'),'l','m'),'o','y')
'jimmy'

The key is that you have to pass self explicitly, because the alias is a kind of function that takes an extra argument that takes self:

>>> type(r)
<type 'method_descriptor'>

Define your own class, with a shorter method name.

For example, if you're using the method replace() belonging to the String class, you could make your own class S have a method called q which does the same thing.

Here is one implementation:

class m(str):
 def q(a,b,c):return m(a.replace(b,c))

Here is a much better implementation:

class m(str):q=lambda a,b,c:m(a.replace(b,c))

Use it like so:

s="Hello"
s=m(s).q('H','J').q('e','i').q('l','m').q('o','y')

This is a few characters shorter anyway

j=iter('HJeilmoy')
for i in j:s=s.replace(i,next(j))

even shorter for a small number of replacements is

for i in['HJ','ei','lm','oy']:s=s.replace(*i)

of course this just covers one particular case. However code golf is all about finding those special cases that can save you bytes.

It's possible to write a wrapper function that handles the general case, but the code will be too large to have a place in most code golf challenges.

You instead need to think "I can do this transformation efficiently (strokewise) with str.replace. Can I shift the internal representation of my solution to take advantage of that? (without wasting so many strokes to negate the advantage)"