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Implementing slicing in __getitem__
... a slice object when the object is sliced. Simply look at the start, stop, and step members of the slice object in order to get the components for the slice.
>>> class C(object):
... def __getitem__(self, val):
... print val
...
>>> c = C()
>>> c[3]
3
>>> ...
Difference between ProcessBuilder and Runtime.exec()
I'm trying to execute an external command from java code, but there's a difference I've noticed between Runtime.getRuntime().exec(...) and new ProcessBuilder(...).start() .
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COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...
Bottom Line
Use either COUNT(field) or COUNT(*), and stick with it consistently, and if your database allows COUNT(tableHere) or COUNT(tableHere.*), use that.
In short, don't use COUNT(1) for anything. It's a one-trick pony, which rarely does what you want, and in those ...
Handler vs AsyncTask vs Thread [closed]
I got slightly confused about the differences between Handlers , AsyncTask and Threads in Android. I've read quite a few blogs and questions here in StackOverflow.
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How to tell if JRE or JDK is installed
... testing. However, when I got a java application working on this computer, and then tried it on another, it complained that JDK was required. How can I check if JDK was somehow installed on my system? Note: the computer in question is a Mac.
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Null vs. False vs. 0 in PHP
...m told that good developers can spot/utilize the difference between Null and False and 0 and all the other good "nothing" entities.
What is the difference, specifically in PHP? Does it have something to do with === ?
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Cancellation token in Task constructor: why?
...nyway.
If the body of the task is also monitoring the cancellation token and throws an OperationCanceledException containing that token
(which is what ThrowIfCancellationRequested does), then when the task
sees that OperationCanceledException, it checks whether the OperationCanceledException's...
how to provide a swap function for my class?
...is the proper use of swap. Write it this way when you write "library" code and want to enable ADL (argument-dependent lookup) on swap. Also, this has nothing to do with SFINAE.
// some algorithm in your code
template<class T>
void foo(T& lhs, T& rhs) {
using std::swap; // enable '...
Is the order of iterating through std::map known (and guaranteed by the standard)?
...te from std::map::begin() to std::map::end() using a for , does the standard guarantee that I'll iterate consequently through the elements with keys, sorted in ascending order?
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Python: fastest way to create a list of n lists
...None, n)]
It does not have to create a new int object in every iteration and is about 15 % faster on my machine.
Edit: Using NumPy, you can avoid the Python loop using
d = numpy.empty((n, 0)).tolist()
but this is actually 2.5 times slower than the list comprehension.
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