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Is “IF” expensive?
...
At the very lowest level (in the hardware), yes, ifs are expensive. In order to understand why, you have to understand how pipelines work.
The current instruction to be executed is stored in something typically called the instruction pointer (IP) or program counter (PC); these terms are synonym...
Resetting generator object in Python
...to create a second version of your generator:
y = FunctionWithYield()
y, y_backup = tee(y)
for x in y:
print(x)
for x in y_backup:
print(x)
This could be beneficial from memory usage point of view if the original iteration might not process all the items.
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What does the Ellipsis object do?
...[1:2, ..., 0]
Its interpretation is purely up to whatever implements the __getitem__ function and sees Ellipsis objects there, but its main (and intended) use is in the numpy third-party library, which adds a multidimensional array type. Since there are more than one dimensions, slicing becomes m...
Can I install Python windows packages into virtualenvs?
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Yes, you can. All you need is
easy_install
binary_installer_built_with_distutils.exe
Surprised? It looks like binary installers for Windows made with distutils combine .exe with .zip into one .exe file. Change extension to .zip to see it's a valid zip fil...
Execute code when Django starts ONCE only?
...d executed once.
urls.py
from django.confs.urls.defaults import *
from my_app import one_time_startup
urlpatterns = ...
one_time_startup()
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Fatal error in launcher: Unable to create process using “”C:\Program Files (x86)\Python33\python.exe
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Here's how I solved it:
open pip.exe in 7zip and extract __main__.py to Python\Scripts folder.
In my case it was C:\Program Files (x86)\Python27\Scripts
Rename __main__.py to pip.py
Run it! python pip.py install something
EDIT:
If you want to be able to do pip install something...
What is the size of an enum in C?
... having only that, the following is valid i think: enum { LAST = INT_MAX, LAST1, LAST2 }; so LAST2 is not representable in int, but there wasn't an expression defining it.
– Johannes Schaub - litb
Dec 14 '08 at 1:33
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git command to move a folder inside another
...Name newFolderName
got
fatal: bad source, source=oldFolderName/somepath/__init__.py, dest
ination=ESWProj_Base/ESWProj_DebugControlsMenu/somepath/__init__.py
I did
git rm -r oldFolderName
and
git add newFolderName
and I don't see old git history in my project. At least my project is not l...
Difference between the Facade, Proxy, Adapter and Decorator design patterns? [closed]
...tances (and the dreaded diamond) you will look out for mixins -- which are ordered linear chaining of interfaces to get around the problems of multiple inheritance. However, mixins don't mix that well. And we end up with traits -- yes those stateless little blobs of behavior that you see pop-up all ...
MySQL Results as comma separated list
...----------------------------------------+
GROUP_CONCAT with DISTINCT and ORDER BY
SELECT GROUP_CONCAT(DISTINCT TaskName ORDER BY TaskName DESC)
FROM Tasks;
Result:
+--------------------------------------------------------+
| GROUP_CONCAT(DISTINCT TaskName ORDER BY TaskName DESC) |
+----------...