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Difference between . and : in Lua
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To be completely precise, obj:method(1, 2, 3) is the same as
do
local _obj = obj
_obj.method(_obj, 1, 2, 3)
end
Why the local variable? Because, as many have pointed out, obj:method() only indexes _ENV once to get obj. This normally just important when considering speed, but consider this s...
MySQL: selecting rows where a column is null
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NULL = NULL is not really FALSE - it's NULL again. But it's not TRUE either, so IF(NULL = NULL) won't execute.
– Konerak
Jan 12 '11 at 19:50
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Is there a way of making strings file-path safe in c#?
...ered Dec 2 '08 at 7:35
Jonathan AllenJonathan Allen
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What is the meaning of the /dist directory in open source projects?
Since I first saw a dist/ directory in many open source projects, usually on GitHub, I've been wondering what it means.
4...
Filter rows which contain a certain string
...n easily extend to more than one column.
Below also a solution with filter_all in order to find the string in any column,
using diamonds as example, looking for the string "V"
library(tidyverse)
String in only one column
# for only one column... extendable to more than one creating a column list in...
How to elegantly deal with timezones
...t is that inside the DB, date/times are stored in UTC. When on the server, all date/times should be dealt with in UTC. However, I see three problems that I'm trying to overcome:
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List comprehension: Returning two (or more) items for each item
...bda x: x + 2
>>> g = lambda x: x ** 2
>>> list(chain.from_iterable((f(x), g(x)) for x in range(3)))
[2, 0, 3, 1, 4, 4]
Timings:
from timeit import timeit
f = lambda x: x + 2
g = lambda x: x ** 2
def fg(x):
yield f(x)
yield g(x)
print timeit(stmt='list(chain.from_itera...
Java equivalent to #region in C#
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Actually this can be achieved. If you scroll down on this post "Yaqub Ahmad" explains how to get this functionality. Also here is a link (kosiara87.blogspot.com/2011/12/…) that shows you how to add it to your existing eclipse e...
Sleep for milliseconds
... facilities:
#include <chrono>
#include <thread>
std::this_thread::sleep_for(std::chrono::milliseconds(x));
Clear and readable, no more need to guess at what units the sleep() function takes.
share
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OpenCV C++/Obj-C: Detecting a sheet of paper / Square Detection
...e I was unable to find a relevant implementation I decided to accept the challenge.
I made some modifications to the squares demo present in OpenCV and the resulting C++ code below is able to detect a sheet of paper in the image:
void find_squares(Mat& image, vector<vector<Point> >...