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When is “i += x” different from “i = i + x” in Python?
...
This depends entirely on the object i.
+= calls the __iadd__ method (if it exists -- falling back on __add__ if it doesn't exist) whereas + calls the __add__ method1 or the __radd__ method in a few cases2.
From an API perspective, __iadd__ is supposed to be used for modifyi...
How do I achieve the theoretical maximum of 4 FLOPs per cycle?
...m>
using namespace std;
typedef unsigned long long uint64;
double test_dp_mac_SSE(double x,double y,uint64 iterations){
register __m128d r0,r1,r2,r3,r4,r5,r6,r7,r8,r9,rA,rB,rC,rD,rE,rF;
// Generate starting data.
r0 = _mm_set1_pd(x);
r1 = _mm_set1_pd(y);
r8 = _mm_set1_pd(...
Can modules have properties the same way that objects can?
...ance. So, for example, your m.py module file could be:
import sys
class _M(object):
def __init__(self):
self.c = 0
def afunction(self):
self.c += 1
return self.c
y = property(afunction)
sys.modules[__name__] = _M()
...
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...
A python class that acts like dict
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class Mapping(dict):
def __setitem__(self, key, item):
self.__dict__[key] = item
def __getitem__(self, key):
return self.__dict__[key]
def __repr__(self):
return repr(self.__dict__)
def __len__(self):
re...
Python extending with - using super() Python 3 vs Python 2
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super() (without arguments) was introduced in Python 3 (along with __class__):
super() -> same as super(__class__, self)
so that would be the Python 2 equivalent for new-style classes:
super(CurrentClass, self)
for old-style classes you can always use:
class Classname(OldStyleParen...
Purpose of Python's __repr__
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__repr__ should return a printable representation of the object, most likely one of the ways possible to create this object. See official documentation here. __repr__ is more for developers while __str__ is for end users.
A ...
Compare object instances for equality by their attributes
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You should implement the method __eq__:
class MyClass:
def __init__(self, foo, bar):
self.foo = foo
self.bar = bar
def __eq__(self, other):
if not isinstance(other, MyClass):
# don't attempt to compare against ...
Difference between left join and right join in SQL Server [duplicate]
... two table with following records:
Table A
id firstname lastname
___________________________
1 Ram Thapa
2 sam Koirala
3 abc xyz
6 sruthy abc
Table B
id2 place
_____________
1 Nepal
2 USA
3 Lumbini
5 Kathmandu
Inne...
How to retrieve a module's path?
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import a_module
print(a_module.__file__)
Will actually give you the path to the .pyc file that was loaded, at least on Mac OS X. So I guess you can do:
import os
path = os.path.abspath(a_module.__file__)
You can also try:
path ...