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Proper use of beginBackgroundTaskWithExpirationHandler
...teger)beginTaskWithCompletionHandler:(CompletionBlock)_completion;
{
//read the counter and increment it
NSUInteger taskKey;
@synchronized(self) {
taskKey = self.taskKeyCounter;
self.taskKeyCounter++;
}
//tell the OS to start a task that should continue in the ...
Reverse a string in Python
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@Paolo's s[::-1] is fastest; a slower approach (maybe more readable, but that's debatable) is ''.join(reversed(s)).
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What is syntax for selector in CSS for next element?
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@BoltClock Yes you are correct, I mis-read the spec and deleted that comment because it was wrong. This selector will only match the p that is immediately preceded by h1.hc-reform (with the same parent element, of course).
– Josh Stodola
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The new syntax “= default” in C++11
...ormly for each of these special member functions makes your code easier to read by explicitly stating your intent.
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Performance of static methods vs instance methods
... instance method within the same class, it'll likely be in that register already (unless it was stashed and the register used for some reason) and hence there is no action required to set the this to what it needs to be set to. This applies to a certain extent to e.g. the first two parameters to the...
Is there a command to list all Unix group names? [closed]
...etent group
The reason is that on networked systems, groups may not only read from /etc/group file, but also obtained through LDAP or Yellow Pages (the list of known groups comes from the local group file plus groups received via LDAP or YP in these cases).
If you want just the group names you ca...
Android List Preferences: have summary as selected value?
...ou need API >= 11 for "%s" ? In my tests, "%s" doesn't work with Gingerbread and earlier versions.
– andreas1724
Mar 14 '16 at 23:56
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How does the “this” keyword work?
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I recommend reading Mike West's article Scope in JavaScript (mirror) first. It is an excellent, friendly introduction to the concepts of this and scope chains in JavaScript.
Once you start getting used to this, the rules are actually pre...
How to go back (ctrl+z) in vi/vim
... use the u button to undo the last modification. (And Ctrl+R to redo it).
Read more about it at: http://vim.wikia.com/wiki/Undo_and_Redo
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Constant Amortized Time
...twice as long before doing it! The cost of each enlargement can thus be "spread out" among the insertions. This means that in the long term, the total time taken for adding m items to the array is O(m), and so the amortised time (i.e. time per insertion) is O(1).
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