There’s no simple, straightforward way to do this with a constructor function. This is because special things happen when you use the new keyword to call a constructor function, and so if you’re not going to do that, you have to emulate all of those special things. They are: Creating a new object instance (you’re … Read more
Basically performSelector allows you to dynamically determine which selector to call a selector on the given object. In other words the selector need not be determined before runtime. Thus even though these are equivalent: [anObject aMethod]; [anObject performSelector:@selector(aMethod)]; The second form allows you to do this: SEL aSelector = findTheAppropriateSelectorForTheCurrentSituation(); [anObject performSelector: aSelector]; before you … Read more
I think the reason is that people are used to statically typed languages that have very limited and inexpressive type systems. These are languages like Java, C++, Pascal, etc. Instead of going in the direction of more expressive type systems and better type inference, (as in Haskell, for example, and even SQL to some extent), … Read more
The ability of the interpreter to deduce type and type conversions makes development time faster, but it also can provoke runtime failures which you just cannot get in a statically typed language where you catch them at compile time. But which one’s better (or even if that’s always true) is hotly discussed in the community … Read more
Actually, a concise rule for Python Scope resolution, from Learning Python, 3rd. Ed.. (These rules are specific to variable names, not attributes. If you reference it without a period, these rules apply.) LEGB Rule Local — Names assigned in any way within a function (def or lambda), and not declared global in that function Enclosing-function … Read more
In a language implementing classical inheritance like Java, C# or C++ you start by creating a class–a blueprint for your objects–and then you can create new objects from that class or you can extend the class, defining a new class that augments the original class. In JavaScript you first create an object (there is no … Read more