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How to override the copy/deepcopy operations for a Python object?
...ully, but this is the first time I've actually gone about overloading the __copy__ and __deepcopy__ methods. I've already Googled around and looked through the built-in Python modules to look for instances of the __copy__ and __deepcopy__ functions (e.g. sets.py , decimal.py , and fracti...
Can't pickle when using multiprocessing Pool.map()
...r program to allow such methods to be pickled, registering it with the copy_reg standard library method.
For example, Steven Bethard's contribution to this thread (towards the end of the thread) shows one perfectly workable approach to allow method pickling/unpickling via copy_reg.
...
How do I get the number of elements in a list?
...objects with a "size" in Python, in particular, have an attribute called ob_size, where the number of elements in the object is cached. So checking the number of objects in a list is very fast.
But if you're checking if list size is zero or not, don't use len - instead, put the list in a boolean co...
How can I dynamically create derived classes from a base class
...s with dynamic
names and parameter names.
The parameter verification in __init__ just does not allow
unknown parameters, if you need other verifications, like
type, or that they are mandatory, just add the logic
there:
class BaseClass(object):
def __init__(self, classtype):
self._typ...
Python - Get path of root project structure
...tils.py
In definitions.py you can define (this requires import os):
ROOT_DIR = os.path.dirname(os.path.abspath(__file__)) # This is your Project Root
Thus, with the Project Root known, you can create a variable that points to the location of the configuration (this can be defined anywhere, but ...
Multi-line string with extra space (preserved indentation)
...o use a helper function and some variable substitution tricks:
unset text
_() { text="${text}${text+
}${*}"; }
# That's an empty line which demonstrates the reasoning behind
# the usage of "+" instead of ":+" in the variable substitution
# above.
_ ""
_ "this is line one"
_ "this is line two"
_ "...
Class with Object as a parameter
...
class Classic: pass
class NewStyle(object): pass
print(dir(Classic))
# ['__doc__', '__module__']
print(dir(NewStyle))
# ['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__',...
Getting the class name of an instance?
...
Have you tried the __name__ attribute of the class? ie type(x).__name__ will give you the name of the class, which I think is what you want.
>>> import itertools
>>> x = itertools.count(0)
>>> type(x).__name__
'count...
Adding a Method to an Existing Object Instance
...ion foo at 0x00A98D70>
>>> a.bar
<bound method A.bar of <__main__.A instance at 0x00A9BC88>>
>>>
Bound methods have been "bound" (how descriptive) to an instance, and that instance will be passed as the first argument whenever the method is called.
Callables that ar...
Accessing class variables from a list comprehension in the class definition
...(1)]
... return Foo
...
>>> dis.dis(foo)
2 0 LOAD_BUILD_CLASS
1 LOAD_CONST 1 (<code object Foo at 0x10a436030, file "<stdin>", line 2>)
4 LOAD_CONST 2 ('Foo')
7 MAKE_FUNCTION ...