Counting instances of a class?

You could consider using a class attribute to provide a counter. Each instance needs only to ask for the next value. They each get something unique. Eg: from itertools import count class Obj(object): _ids = count(0) def __init__(self): = next(self._ids)

Assignment of objects in VB6

Like many modern languages, VB6 has value types and reference types. Classes define reference types. On the other hand, your basic types like Integer are value types. The basic difference is in assignment: Dim a as Integer Dim b as Integer a = 2 b = a a = 1 The result is that a … Read more

What exactly is a Class Factory?

Here’s some supplemental information that may help better understand several of the other shorter, although technically correct, answers. In the strictest sense a Class Factory is a function or method that creates or selects a class and returns it, based on some condition determined from input parameters or global context. This is required when the … Read more

Template in Fortran?

Fortran does not have templates, but you can put the code common to the functions handling different types in an include file as a kludge to simulate templates, as shown in this code: ! file “” ! function cumul(xx) result(yy) ! return in yy(:) the cumulative sum of xx(:) ! type, intent(in) :: xx(:) ! … Read more

List of class’s properties in swift

Using Mirror Here’s a pure Swift solution with some limitations: protocol PropertyNames { func propertyNames() -> [String] } extension PropertyNames { func propertyNames() -> [String] { return Mirror(reflecting: self).children.flatMap { $0.label } } } class Person : PropertyNames { var name = “Sansa Stark” var awesome = true } Person().propertyNames() // [“name”, “awesome”] Limitations: Returns … Read more

Types and classes of variables

In R every “object” has a mode and a class. The former represents how an object is stored in memory (numeric, character, list and function) while the later represents its abstract type. For example: d <- data.frame(V1=c(1,2)) class(d) # [1] “data.frame” mode(d) # [1] “list” typeof(d) # list As you can see data frames are … Read more

What are public, private and protected in object oriented programming?

They are access modifiers and help us implement Encapsulation (or information hiding). They tell the compiler which other classes should have access to the field or method being defined. private – Only the current class will have access to the field or method. protected – Only the current class and subclasses (and sometimes also same-package … Read more