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Readonly Properties in Objective-C?

...ing"; // Notice the underscore prefix of var name. That’s it, that’s all you need. No muss, no fuss. Details As of Xcode 4.4 and LLVM Compiler 4.0 (New Features in Xcode 4.4), you need not mess with the chores discussed in the other answers: The synthesize keyword Declaring a variable Re-...
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What is setup.py?

... It helps to install a python package foo on your machine (can also be in virtualenv) so that you can import the package foo from other projects and also from [I]Python prompts. It does the similar job of pip, easy_install etc., Using setup.py Let's star...
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How does collections.defaultdict work?

... Usually, a Python dictionary throws a KeyError if you try to get an item with a key that is not currently in the dictionary. The defaultdict in contrast will simply create any items that you try to access (provided of course th...
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Using “super” in C++

... the first time C++ was standardized. Dag Bruck proposed this extension, calling the base class "inherited." The proposal mentioned the multiple inheritance issue, and would have flagged ambiguous uses. Even Stroustrup was convinced. After discussion, Dag Bruck (yes, the same person making the p...
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Python memoising/deferred lookup property decorator

...nce, but they're a real bottleneck to calculate that first time and only really accessed for special cases. Hence they can also be cached after they've been retrieved from the database (this therefore fits the definition of memoisation where the input is simply "no input"). ...
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Python decorators in classes

...ething like this do what you need? class Test(object): def _decorator(foo): def magic( self ) : print "start magic" foo( self ) print "end magic" return magic @_decorator def bar( self ) : print "normal call" test = Test() t...
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define() vs. const

...nts: Either using the const keyword or using the define() function: const FOO = 'BAR'; define('FOO', 'BAR'); The fundamental difference between those two ways is that const defines constants at compile time, whereas define defines them at run time. This causes most of const's disadvantages. Some ...
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How to return a value from __init__ in Python?

...you want to return an instance variable (or function). >>> class Foo: ... def __init__(self): ... return 42 ... >>> foo = Foo() Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: __init__() should return None ...
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How to make a python, command-line program autocomplete arbitrary things NOT interpreter

...ts, i.e. --help, --verbose and --version. For your purposes, you'll essentially want to customise the values that are put into opts. Do have a look at the example on the linked page, it's all pretty straightforward. share ...
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Python: Best way to add to sys.path relative to the current running script

...o have a library located in project/lib and want the scripts to automatically load it. This is what I normally use at the top of each script: ...