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C++ preprocessor __VA_ARGS__ number of arguments

... This is actually compiler dependent, and not supported by any standard. Here however you have a macro implementation that does the count: #define PP_NARG(...) \ PP_NARG_(__VA_ARGS__,PP_RSEQ_N()) #define PP_NARG_(...) \ ...
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How to duplicate sys.stdout to a log file?

...est way to accomplish logging when a python app is making a lot of system calls? 17 Answers ...
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Accessing Object Memory Address

When you call the object.__repr__() method in Python you get something like this back: 9 Answers ...
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String concatenation in Ruby

...ficient in term of memory/speed from what I've seen (not measured though). All three methods will throw an uninitialized constant error when ROOT_DIR is nil. When dealing with pathnames, you may want to use File.join to avoid messing up with pathname separator. In the end, it is a matter of taste....
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Parse JSON String into a Particular Object Prototype in JavaScript

...olution below that applies Object.assign(..) recursively that can automatically resolve properties (with a bit of information provided in advance) – vir us Dec 8 '17 at 16:13 ...
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Check if OneToOneField is None in Django

... Thank you for this solution. Unfortunately, this doesn't work all the time. In case you want to work with select_related() now or in the future -- or maybe even to be sure you also handle other sorts of magic which may happen elsewhere -- you have to extend the test as follows: if hasat...
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What does $_ mean in PowerShell?

... This is the variable for the current value in the pipe line, which is called $PSItem in Powershell 3 and newer. 1,2,3 | %{ write-host $_ } or 1,2,3 | %{ write-host $PSItem } For example in the above code the %{} block is called for every value in the array. The $_ or $PSItem variable ...
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How to access outer class from an inner class?

...d Jan 7 '10 at 23:54 Daniel VassalloDaniel Vassallo 301k6666 gold badges475475 silver badges424424 bronze badges ...
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What are the applications of binary trees?

...ningless - they are not a data structure, but a family of data structures, all with different performance characteristics. While it is true that unbalanced binary trees perform much worse than self-balancing binary trees for searching, there are many binary trees (such as binary tries) for which "b...
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How can I maintain fragment state when added to the back stack?

... back stack. However, when I return to FragmentA (by pressing back), a totally new FragmentA is created and the state it was in is lost. I get the feeling I'm after the same thing as this question, but I've included a complete code sample to help root out the issue: ...