In the function __getattr__(), if a referred variable is not found then it gives an error. How can I check to see if a variable or method exists as part of an object?
import string
import logging
class Dynamo:
def __init__(self,x):
print “In Init def”
self.x=x
def __repr__(self):
print self.x
def __str__(self):
print self.x
def __int_….
The Zen of Python states that there should only be one way to do things- yet frequently I run into the problem of deciding when to use a function versus when to use a method.
Let’s take a trivial example- a ChessBoard object. Let’s say we need some way to get all the legal King moves available on the board. Do we write ChessBoard.get_king_moves() ….
In Python, is there a way to bind an unbound method without calling it?
I am writing a wxPython program, and for a certain class I decided it’d be nice to group the data of all of my buttons together as a class-level list of tuples, like so:
class MyWidget(wx.Window):
buttons = [(“OK”, OnOK),
(“Cancel”, OnCancel)]
# …
….
I am having trouble understanding the Initialization of classes.
What’s the point of them and how do we know what to include in them? Does writing in classes require a different type of thinking versus creating functions (I figured I could just create functions and then just wrap them in a class so I can re-use them. Will that work?)
Here’s an exa….
In Python, I’m trying to run a method in a class and I get an error:
Traceback (most recent call last):
File “C:\Users\domenico\Desktop\py\main.py”, line 8, in
fibo.f()
TypeError: unbound method f() must be called with fibo instance
as first argument (got nothing instead)
Code: (swineflu.py)
class fibo:
a=0
b=0
de….
Is there a built-in method in Python to get an array of all a class’ instance variables? For example, if I have this code:
class hi:
def __init__(self):
self.ii = “foo”
self.kk = “bar”
Is there a way for me to do this:
>>> mystery_method(hi)
[“ii”, “kk”]
Edit: I originally had asked for class variables erroneously.
….
I know that __call__ method in a class is triggered when the instance of a class is called. However, I have no idea when I can use this special method, because one can simply create a new method and perform the same operation done in __call__ method and instead of calling the instance, you can call the method.
I would really appreciate it if someo….
I know that python has a len() function that is used to determine the size of a string, but I was wondering why it’s not a method of the string object.
Update
Ok, I realized I was embarrassingly mistaken. __len__() is actually a method of a string object. It just seems weird to see object oriented code in Python using the len function on string ob….
This “underscoring” seems to occur a lot, and I was wondering if this was a requirement in the Python language, or merely a matter of convention?
Also, could someone name and explain which functions tend to have the underscores, and why (__init__, for instance)?
….
In Python, is the following the only way to get the number of elements?
arr.__len__()
If so, why the strange syntax?
….