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Difference between a theta join, equijoin and natural join
... yourself).
** I don't quite know what the result of SELECT * FROM table_expression; is. I know it is not a relation because, among other reasons, it can have columns with duplicate names or a column with no name. I know it is not a set because, among other reasons, the column order is significan...
Mac zip compress without __MACOSX folder?
... built in zip compressor in Mac OSX, it results in an extra folder titled "__MACOSX" created in the extracted zip.
13 Answe...
How to get the return value from a thread in python?
...cutor() as executor:
future = executor.submit(foo, 'world!')
return_value = future.result()
print(return_value)
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How to change a module variable from another module?
...oo, not the actual value. Try to import bar.py directly with import bar in __init__.py and conduct your experiment there by setting bar.a = 1. This way, you will actually be modifying bar.__dict__['a'] which is the 'real' value of a in this context.
It's a little convoluted with three layers but ba...
What does “#define _GNU_SOURCE” imply?
...
Defining _GNU_SOURCE has nothing to do with license and everything to do with writing (non-)portable code. If you define _GNU_SOURCE, you will get:
access to lots of nonstandard GNU/Linux extension functions
access to traditional fu...
What is the meaning of single and double underscore before an object name?
...owever, nothing special is done with the name itself.
To quote PEP-8:
_single_leading_underscore: weak "internal use" indicator. E.g. from M import * does not import objects whose name starts with an underscore.
Double Underscore (Name Mangling)
From the Python docs:
Any identifier of th...
How can I handle time zones in my webapp?
...s ambiguously used. This looks like a reference: en.wikipedia.org/wiki/Tz_database From what I can tell a "timezone" is "Area/Location", e.g. "America/New_York". That appears to be geographic which is great because for instance America/Los_Angeles means BOTH PST and PDT depending on whether the ...
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...
__init__ for unittest.TestCase
...
Try this:
class TestingClass(unittest.TestCase):
def __init__(self, *args, **kwargs):
super(TestingClass, self).__init__(*args, **kwargs)
self.gen_stubs()
You are overriding the TestCase's __init__, so you might want to let the base class handle the arguments ...
How do I create a constant in Python?
...f you are in a class, the equivalent would be:
class Foo(object):
CONST_NAME = "Name"
if not, it is just
CONST_NAME = "Name"
But you might want to have a look at the code snippet Constants in Python by Alex Martelli.
As of Python 3.8, there's a typing.Final variable annotation that will tell ...