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Why is “if not someobj:” better than “if someobj == None:” in Python?
...r not ? This is done using the following algorithm :
If the object has a __nonzero__ special method (as do numeric built-ins, int and float), it calls this method. It must either return a bool value which is then directly used, or an int value that is considered False if equal to zero.
Otherwise, ...
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.
...
Creating a dynamic choice field
...passing the user to the form init
class waypointForm(forms.Form):
def __init__(self, user, *args, **kwargs):
super(waypointForm, self).__init__(*args, **kwargs)
self.fields['waypoints'] = forms.ChoiceField(
choices=[(o.id, str(o)) for o in Waypoint.objects.filter(use...
PHP function overloading
...c function that takes in a variable number of arguments. You would use func_num_args() and func_get_arg() to get the arguments passed, and use them normally.
For example:
function myFunc() {
for ($i = 0; $i < func_num_args(); $i++) {
printf("Argument %d: %s\n", $i, func_get_arg($i))...
unique object identifier in javascript
... var id = 0;
Object.id = function(o) {
if ( typeof o.__uniqueid == "undefined" ) {
Object.defineProperty(o, "__uniqueid", {
value: ++id,
enumerable: false,
// This could go either way, depending on your...
Does python have an equivalent to Java Class.forName()?
...honic way of doing it.
Here's a function that does what you want:
def get_class( kls ):
parts = kls.split('.')
module = ".".join(parts[:-1])
m = __import__( module )
for comp in parts[1:]:
m = getattr(m, comp)
return m
You can use the return value of this ...
How to reliably open a file in the same directory as a Python script
...
I always use:
__location__ = os.path.realpath(
os.path.join(os.getcwd(), os.path.dirname(__file__)))
The join() call prepends the current working directory, but the documentation says that if some path is absolute, all other paths lef...
Among $_REQUEST, $_GET and $_POST which one is the fastest?
...
$_REQUEST, by default, contains the contents of $_GET, $_POST and $_COOKIE.
But it's only a default, which depends on variables_order ; and not sure you want to work with cookies.
If I had to choose, I would probably not us...
Underscore vs Double underscore with variables and methods [duplicate]
Somebody was nice enough to explain to me that __method() mangles but instead of bothering him further since there are a lot of other people who need help I was wondering if somebody could elaborate the differences further.
...
What are “named tuples” in Python?
...e following:
pt1 = (1.0, 5.0)
pt2 = (2.5, 1.5)
from math import sqrt
line_length = sqrt((pt1[0]-pt2[0])**2 + (pt1[1]-pt2[1])**2)
Using a named tuple it becomes more readable:
from collections import namedtuple
Point = namedtuple('Point', 'x y')
pt1 = Point(1.0, 5.0)
pt2 = Point(2.5, 1.5)
from ...