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Create a “with” block on several context managers? [duplicate]
...rite:
with A() as X, B() as Y, C() as Z:
do_something()
This is normally the best method to use, but if you have an unknown-length list of context managers you'll need one of the below methods.
In Python 3.3, you can enter an unknown-length list of context managers by using contextlib.Exit...
What are some (concrete) use-cases for metaclasses?
...a couple functions I found that I was able to increment the figure count, call draw manually, etc, but I needed to do these before and after every plotting call. So to create both an interactive plotting wrapper and an offscreen plotting wrapper, I found it was more efficient to do this via metacla...
Numpy - add row to array
...2, 0]])
X = array([[0, 1, 2], [1, 2, 0], [2, 1, 2], [3, 2, 0]])
add to A all rows from X where the first element < 3:
import numpy as np
A = np.vstack((A, X[X[:,0] < 3]))
# returns:
array([[0, 1, 2],
[0, 2, 0],
[0, 1, 2],
[1, 2, 0],
[2, 1, 2]])
...
Best way to strip punctuation from a string
...s working with the same datatype, but the approach in this answer works equally well for both, which is handy.
– Richard J
Jan 16 '15 at 9:35
38
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Perl flags -pe, -pi, -p, -w, -d, -i, -t?
...eem to be mostly made up of punctuation :-)
The command line switches are all detailed in perlrun. (available from the command line by calling perldoc perlrun)
Going into the options briefly, one-by-one:
-p: Places a printing loop around your command so that it acts on each
line of standard ...
Stop “developer tools access needs to take control of another process for debugging to continue” ale
...
Per Zev Eisenberg's answer, reinstalling Xcode 4.2.1 worked. However, it might be easier to just patch the /etc/authorization file with the following diff.
<key>system.privilege.taskport.debug</key>
<dict>
<...
How to combine two or more querysets in a Django view?
...sets into a list is the simplest approach. If the database will be hit for all querysets anyway (e.g. because the result needs to be sorted), this won't add further cost.
from itertools import chain
result_list = list(chain(page_list, article_list, post_list))
Using itertools.chain is faster than...
Changing the image source using jQuery
...
Yes. This finally did the trick. .destroy() doesn't go nearly far enough. Nuking all the html and than init again actually works when swapping out images of various sizes and such.
– Matt J.
Apr 11 '...
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.al
I just discovered a logical bug in my code which was causing all sorts of problems. I was inadvertently doing a bitwise AND instead of a logical AND .
...
How can I do a line break (line continuation) in Python?
...
Actually, you have the style guide's preference exactly backwards. Implicit continuation is preferred, explicit backslash is to be used only if necessary.
– Carl Meyer
Sep 11 '08 at 19:00
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