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What does the caret operator (^) in Python do?
...his way:
1000 # 8 (binary)
0011 # 3 (binary)
---- # APPLY XOR ('vertically')
1011 # result = 11 (binary)
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Is it intended by the C++ standards committee that in C++11 unordered_map destroys what it inserts?
... always move from its argument. It's supposed to move if the argument is really an rvalue, and copy if it's an lvalue.
The behaviour, you observe, which always moves, is a bug in libstdc++, which is now fixed according to a comment on the question. For those curious, I took a look at the g++-4.8 he...
Is errno thread-safe?
...t errno; so my question is, is it safe to check errno value after some calls or use perror() in multi-threaded code. Is this a thread safe variable? If not, then whats the alternative ?
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Python constructors and __init__
Why are constructors indeed called "Constructors"? What is their purpose and how are they different from methods in a class?
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Express-js can't GET my static files, why?
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In case of new install you should verify that your express module is properly installed (expressjs.com/en/starter/installing.html) then you should check the path and your directory name like Giacomo said ;)
– Spl2nky
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Setting the selected value on a Django forms.ChoiceField
...rying to assign the selected value to a ChoiceField.
If you have already called super().__init__ in your Form class, you should update the form.initial dictionary, not the field.initial property. If you study form.initial (e.g. print self.initial after the call to super().__init__), it will contai...
Specify sudo password for Ansible
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For example, you might have a playbook something like this:
- hosts: all
vars_files:
- secret
tasks:
- name: Do something as sudo
service: name=nginx state=restarted
sudo: yes
Here we are including a file called secret which will contain our sudo password.
We will...
Reading a huge .csv file
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You are reading all rows into a list, then processing that list. Don't do that.
Process your rows as you produce them. If you need to filter the data first, use a generator function:
import csv
def getstuff(filename, criterion):
with ...
Super-simple example of C# observer/observable with delegates
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The observer pattern is usually implemented with events.
Here's an example:
using System;
class Observable
{
public event EventHandler SomethingHappened;
public void DoSomething() =>
SomethingHappened?.Invoke(this, EventArgs.Empt...
Is there a way to make mv create the directory to be moved to if it doesn't exist?
...ectories don't exist, is there some way to have those directories automatically created, so that you would only have to type
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