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Python != operation vs “is not”
...ght hand side and the left hand side are equal objects (according to their __eq__ or __cmp__ methods.)
is is an identity test. It checks whether the right hand side and the left hand side are the very same object. No methodcalls are done, objects can't influence the is operation.
You use is (and i...
relative path in require_once doesn't work
...
Use
__DIR__
to get the current path of the script and this should fix your problem.
So:
require_once(__DIR__.'/../class/user.php');
This will prevent cases where you can run a PHP script from a different folder and therefo...
In Python, how do I determine if an object is iterable?
...'ve lately started to get more and more annoyed by objects which only have __getitem__ being considered iterable. There are valid reasons to have __getitem__ in a non-iterable object and with them the above code doesn't work well. As a real life example we can use Faker. The above code reports it be...
How can I create a copy of an object in Python?
... get a copy method (in 2, you'd use a slice to make a copy):
>>> a_list = list('abc')
>>> a_copy_of_a_list = a_list.copy()
>>> a_copy_of_a_list is a_list
False
>>> a_copy_of_a_list == a_list
True
Shallow Copies
Shallow copies are just copies of the outermost cont...
Why is Python 3.x's super() magic?
...lf):
return super(Foo, self).baz() + 42
Spam = Foo
Foo = something_else()
Spam().baz() # liable to blow up
The same applies to using class decorators where the decorator returns a new object, which rebinds the class name:
@class_decorator_returning_new_class
class Foo(Bar):
def baz...
Creating C macro with ## and __LINE__ (token concatenation with positioning macro)
...PASTE2(x, y) TOKENPASTE(x, y)
#define UNIQUE static void TOKENPASTE2(Unique_, __LINE__)(void) {}
Then, __LINE__ gets expanded to the line number during the expansion of UNIQUE (since it's not involved with either # or ##), and then the token pasting happens during the expansion of TOKENPASTE.
It ...
How do I get the opposite (negation) of a Boolean in Python?
... function
There are also two functions in the operator module operator.not_ and it's alias operator.__not__ in case you need it as function instead of as operator:
>>> import operator
>>> operator.not_(False)
True
>>> operator.not_(True)
False
These can be useful if yo...
'is' versus try cast with null check
...ing)
{
var x = (string) o;
}
This translates to the following IL:
IL_0000: nop
IL_0001: ldstr "test"
IL_0006: stloc.0 // o
IL_0007: ldloc.0 // o
IL_0008: isinst System.String
IL_000D: ldnull
IL_000E: cgt.un
IL_0010: stloc.1
IL_0011: ldloc....
What is the difference between class and instance attributes?
...> a.foo.append(5)
>>> b.foo
[5]
>>> class A:
... def __init__(self): self.foo = []
>>> a, b = A(), A()
>>> a.foo.append(5)
>>> b.foo
[]
share
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...
What do all of Scala's symbolic operators mean?
... // Syntactic sugar/composition or common method
<= // Common method
_._ // Typo, though it's probably based on Keyword/composition
:: // Common method
:+= // Common method
The exact meaning of most of these methods depend on the class that is defining them. For example, <= on Int ...