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What is the volatile keyword useful for?
... volatile:
public class Singleton {
private static volatile Singleton _instance; // volatile variable
public static Singleton getInstance() {
if (_instance == null) {
synchronized (Singleton.class) {
if (_instance == null)
_instance = ...
django change default runserver port
...ith the following:
#!/bin/bash
exec ./manage.py runserver 0.0.0.0:<your_port>
save it as runserver in the same dir as manage.py
chmod +x runserver
and run it as
./runserver
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Best algorithm for detecting cycles in a directed graph [closed]
...e following Wikipedia article:
http://en.wikipedia.org/wiki/Topological_sorting
has the pseudo-code for one algorithm, and a brief description of another from Tarjan. Both have O(|V| + |E|) time complexity.
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How to calculate the bounding box for a given lat/lng location?
...return 180.0*radians/math.pi
# Semi-axes of WGS-84 geoidal reference
WGS84_a = 6378137.0 # Major semiaxis [m]
WGS84_b = 6356752.3 # Minor semiaxis [m]
# Earth radius at a given latitude, according to the WGS-84 ellipsoid [m]
def WGS84EarthRadius(lat):
# http://en.wikipedia.org/wiki/Earth_rad...
Converting between datetime, Timestamp and datetime64
...amp(ts)
datetime.datetime(2012, 12, 4, 19, 51, 25, 362455)
>>> np.__version__
'1.8.0.dev-7b75899'
The above example assumes that a naive datetime object is interpreted by np.datetime64 as time in UTC.
To convert datetime to np.datetime64 and back (numpy-1.6):
>>> np.datetime6...
Which $_SERVER variables are safe?
...lue comes from and hence whether it can be trusted for a certain purpose. $_SERVER['HTTP_FOOBAR'] for example is entirely safe to store in a database, but I most certainly wouldn't eval it.
As such, let's divide those values into three categories:
Server controlled
These variables are set by the ...
Specifying rails version to use when creating a new application
...option to create a new application using an older version of Rails.
rails _2.1.0_ new myapp
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Getting SyntaxError for print with keyword argument end=' '
I have this python script where I need to run gdal_retile.py ,
but I get an exception on this line:
14 Answers
...
What belongs in an educational tool to demonstrate the unwarranted assumptions people make in C/C++?
...)<sizeof(int)' is false.
..22 floating point is always IEEE
but 'STDC_IEC_559_is_defined' is false.
..25 pointer arithmetic works outside arrays
but '(diff=&var.int2-&var.int1, &var.int1+diff==&var.int2)' is false.
From what I can say with my puny test cases, you are Stop at...
Get IP address of visitors using Flask for Python
...est object and then get from this same Request object, the attribute remote_addr.
Code example
from flask import request
from flask import jsonify
@app.route("/get_my_ip", methods=["GET"])
def get_my_ip():
return jsonify({'ip': request.remote_addr}), 200
For more information see the Werkzeu...