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How can a Java variable be different from itself?
...
One simple way is to use Float.NaN:
float x = Float.NaN; // <--
if (x == x) {
System.out.println("Ok");
} else {
System.out.println("Not ok");
}
Not ok
You can do the same with Double.NaN.
From JLS §15.21.1....
What is the difference between bottom-up and top-down?
... very rare cases*). This is like memoization but more active, and involves one additional step: You must pick, ahead of time, the exact order in which you will do your computations. This should not imply that the order must be static, but that you have much more flexibility than memoization.
examp...
Any reason not to use '+' to concatenate two strings?
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The assumption that one should never, ever use + for string concatenation, but instead always use ''.join may be a myth. It is true that using + creates unnecessary temporary copies of immutable string object but the other not oft quoted fact is...
How to tell if a string is not defined in a Bash shell script
... empty; fi
You probably can combine the two tests on the second line into one with:
if [ -z "$VAR" -a "${VAR+xxx}" = "xxx" ]; then echo VAR is set but empty; fi
However, if you read the documentation for Autoconf, you'll find that they do not recommend combining terms with '-a' and do recommend us...
Is there a point to minifying PHP?
...er named HipHop that transforms PHP source into C++ code. Rasmus Lerdorf, one of the big PHP guys did a presentation for Digg earlier this year that covers the performance improvements given by HipHop. In short, it's not too much faster than optimizing code and using a bytecode cache. HipHop is o...
Intelligent point label placement in R
... fall into roughly three categories:
You have a small number of points, none which are terribly close together. In this case, one of the solutions you listed in the question is likely to work with fairly minimal tweaking.
You have a small number of points, some of which are too closely packed for ...
How do you unit test a Celery task?
...aly do 2 different test sessions when working with celery tasks. The first one (as I'm suggesting bellow) is completely synchronous and should be the one that makes sure the algorithm does what it should do. The second session uses the whole system (including the broker) and makes sure I'm not havin...
Add column with constant value to pandas dataframe [duplicate]
.... In general, pandas tries to do as much alignment of indices as possible. One downside is that when indices are not aligned you get NaN wherever they aren't aligned. Play around with the reindex and align methods to gain some intuition for alignment works with objects that have partially, totally, ...
Multiple inheritance/prototypes in JavaScript
...ndamental operations.
When creating an object which inherits from another one, we use Object.create(obj). But in this case we want multiple inheritance, so instead of obj I use a proxy that will redirect fundamental operations to the appropriate object.
I use these traps:
The has trap is a trap ...
When do we have to use copy constructors?
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@Martin: I wanted to make sure it was carved in stone. :P
– GManNickG
Jul 19 '10 at 6:04
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