protected methods can be called by any instance of the defining class or its subclasses. private methods can be called only from within the calling object. You cannot access another instance’s private methods directly. Here is a quick practical example: def compare_to(x) self.some_method <=> x.some_method end some_method cannot be private here. It must be protected … Read more
Like puts (which sounds similar), it is designed to work with lines, using the \n character. gets takes an optional argument that is used for “splitting” the input (or “just reading till it arrives). It defaults to the special global variable $/, which contains a \n by default. gets is a pretty generic method for … Read more
Function style casts bring consistency to primitive and user defined types. This is very useful when defining templates. For example, take this very silly example: template<typename T, typename U> T silly_cast(U const &u) { return T(u); } My silly_cast function will work for primitive types, because it’s a function-style cast. It will also work for … Read more
“cannot be subclassed” isn’t a restriction. It’s one of the big advantages: It ensures there there is always only ever exactly the set of values defined in the enum and no more! enum correctly handles serialization. You can do that with type-safe enums as well, but it’s often forgotten (or simply not known). This ensures … Read more
From MSDN: In string concatenation operations, the C# compiler treats a null string the same as an empty string, but it does not convert the value of the original null string. More information on the + binary operator: The binary + operator performs string concatenation when one or both operands are of type string. If … Read more
You can use local variables in extended assembly, but you need to tell the extended assembly construct about them. Consider: #include <stdio.h> int main (void) { int data1 = 10; int data2 = 20; int result; __asm__( ” movl %[mydata1], %[myresult]\n” ” imull %[mydata2], %[myresult]\n” : [myresult] “=&r” (result) : [mydata1] “r” (data1), [mydata2] “r” … Read more
How else could assert(foo == bar); compile down to nothing when NDEBUG is defined?
I’m not an expert on the commas, but I know that standard Pascal was very persnickity about semi-colons being statement separators, not terminators. That meant you had to be very very careful about where you put one if you didn’t want to get yelled at by the compiler. Later Pascal-esque languages (C, Modula-2, Ada, etc.) … Read more
I don’t think you’ll get a better answer than “because the author(s) of that language thought it was better that way”. Personally, I think they’re right. I’d hate to find these lines anywhere in the same source file (and refer to the same object+method)… SomeObject.SomeMethod(); … SOMEOBJECT.SOMEMETHOD(); … someObject.someMethod(); … sOmEoBjEcT.sOmEmEtHoD(); I don’t think anyone … Read more
I can’t speak for the designer of itertools.permutations (Raymond Hettinger), but it seems to me that there are a couple of points in favour of the design: First, if you used a next_permutation-style approach, then you’d be restricted to passing in objects that support a linear ordering. Whereas itertools.permutations provides permutations of any kind of … Read more