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How to run functions in parallel?
...starting'
for i in xrange(10000000): pass
print 'func2: finishing'
if __name__ == '__main__':
p1 = Process(target=func1)
p1.start()
p2 = Process(target=func2)
p2.start()
p1.join()
p2.join()
The mechanics of starting/joining child processes can easily be encapsulated into a functio...
What does 'super' do in Python?
...
What's the difference?
SomeBaseClass.__init__(self)
means to call SomeBaseClass's __init__. while
super(Child, self).__init__()
means to call a bound __init__ from the parent class that follows Child in the instance's Method Resolution Order (MRO).
If th...
Get name of current class?
...
obj.__class__.__name__ will get you any objects name, so you can do this:
class Clazz():
def getName(self):
return self.__class__.__name__
Usage:
>>> c = Clazz()
>>> c.getName()
'Clazz'
...
How to mock an import
...importing A to get what you want:
test.py:
import sys
sys.modules['B'] = __import__('mock_B')
import A
print(A.B.__name__)
A.py:
import B
Note B.py does not exist, but when running test.py no error is returned and print(A.B.__name__) prints mock_B. You still have to create a mock_B.py where ...
How to make a class JSON serializable
...f)
'{"fname": "/foo/bar"}'
In that case you can merely call json.dumps(f.__dict__).
If you want more customized output then you will have to subclass JSONEncoder and implement your own custom serialization.
For a trivial example, see below.
>>> from json import JSONEncoder
>>&g...
Why does this loop produce “warning: iteration 3u invokes undefined behavior” and output more than 4
...e is the full assembly listing:
.file "a.cpp"
.section .text$_ZNKSt5ctypeIcE8do_widenEc,"x"
.linkonce discard
.align 2
LCOLDB0:
LHOTB0:
.align 2
.p2align 4,,15
.globl __ZNKSt5ctypeIcE8do_widenEc
.def __ZNKSt5ctypeIcE8do_widenEc; .scl 2; .type 32; .e...
Set Django IntegerField by choices=… name
...epresents the proper integer.
Like so:
LOW = 0
NORMAL = 1
HIGH = 2
STATUS_CHOICES = (
(LOW, 'Low'),
(NORMAL, 'Normal'),
(HIGH, 'High'),
)
Then they are still integers in the DB.
Usage would be thing.priority = Thing.NORMAL
...
Get fully qualified class name of an object in Python
...lowing program
#! /usr/bin/env python
import foo
def fullname(o):
# o.__module__ + "." + o.__class__.__qualname__ is an example in
# this context of H.L. Mencken's "neat, plausible, and wrong."
# Python makes no guarantees as to whether the __module__ special
# attribute is defined, so we...
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...
What does the “at” (@) symbol do in Python?
...
Example
class Pizza(object):
def __init__(self):
self.toppings = []
def __call__(self, topping):
# When using '@instance_of_pizza' before a function definition
# the function gets passed onto 'topping'.
self.toppings.appe...