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Creating an abstract class in Objective-C

...stringWithFormat:@"%s must be overridden in a subclass/category", __PRETTY_FUNCTION__] userInfo:nil] #define methodNotImplemented() mustOverride() then in your methods you can use this - (void) someMethod { mustOverride(); // or methodNotImplemented(), same thing } Notes: Not sure if maki...
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Purpose of Trigraph sequences in C++?

...teral won't get interpreted as a digraph. For a nice education on various fun with punctuation in C/C++ programs (including a trigraph bug that would defintinely have me pulling my hair out), take a look at Herb Sutter's GOTW #86 article. Addendum: It looks like GCC will not process (and will w...
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How to test which port MySQL is running on and whether it can be connected to?

... 0.0.0.0:* LISTEN 1859/master tcp 0 0 123.189.192.64:7654 0.0.0.0:* LISTEN 2463/monit tcp 0 0 127.0.0.1:24135 0.0.0.0:* LISTEN 21450/memcached tcp 0 0 127.0.0.1:3306 0.0.0.0:* ...
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JavaScript variable assignments from tuples

... 123 Javascript 1.7 added destructured assignment which allows you to do essentially what you are a...
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How Do I Choose Between a Hash Table and a Trie (Prefix Tree)?

...han k time if it's not there Supports ordered traversal No need for a hash function Deletion is straightforward New operations: You can quickly look up prefixes of keys, enumerate all entries with a given prefix, etc. Advantages of linked structure: If there are many common prefixes, the spa...
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In Django, how do I check if a user is in a certain group?

... 123 You can access the groups simply through the groups attribute on User. from django.contrib.au...
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Why doesn't Java offer operator overloading?

...ix object": // C++ YMatrix matrix implementation on CodeProject // http://www.codeproject.com/KB/architecture/ymatrix.aspx // A, B, C, D, E, F are Matrix objects; E = A * (B / 2) ; E += (A - B) * (C + D) ; F = E ; // deep copy of the matrix // Java JAMA matrix implementation (se...
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How to import a Python class that is in a directory above?

...ton Packaging There is a great example project available officially here: https://github.com/pypa/sampleproject A python package is a collection of information about your source code, that can inform other tools how to copy your source code to other computers, and how to integrate your source code ...
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Can two applications listen to the same port?

... iptables -m statistic --mode random --probability 0.5 is fun. – Jed Smith Nov 7 '09 at 21:27 1 ...
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Format timedelta to string

... 2.7 and greater use .total_seconds() method – sk8asd123 Apr 22 '14 at 21:46 28 Don't use .second...