Class does make my life easier as a teacher. The platform affords the opportunity to really create a very dynamic classroom space. Class has figured out how to make the student-teacher experience as real life as possible.
Class has brought the next wave of virtual learning to life. Online education and synchronous learning will only continue to grow in a post pandemic world, and the need for software with tools to enhance the classroom connection digitally is greater than ever.
Classes are a template for creating objects. They encapsulate data with code to work on that data. Classes in JS are built on prototypes but also have some syntax and semantics that are unique to classes.
Like function expressions, class expressions may be anonymous, or have a name that's different from the variable that it's assigned to. However, unlike function declarations, class declarations have the same temporal dead zone restrictions as let or const and behave as if they are not hoisted.
Methods are defined on the prototype of each class instance and are shared by all instances. Methods can be plain functions, async functions, generator functions, or async generator functions. For more information, see method definitions.
The static keyword defines a static method or field for a class. Static properties (fields and methods) are defined on the class itself instead of each instance. Static methods are often used to create utility functions for an application, whereas static fields are useful for caches, fixed-configuration, or any other data that don't need to be replicated across instances.
As seen above, the fields can be declared with or without a default value. Fields without default values default to undefined. By declaring fields up-front, class definitions become more self-documenting, and the fields are always present, which help with optimizations.
It's an error to reference private fields from outside of the class; they can only be read or written within the class body. By defining things that are not visible outside of the class, you ensure that your classes' users can't depend on internals, which may change from version to version.
When a static or instance method is called without a value for this, such as by assigning the method to a variable and then calling it, the this value will be undefined inside the method. This behavior is the same even if the "use strict" directive isn't present, because code within the class body is always executed in strict mode.
\n It's an error to reference private fields from outside of the class; they can only be read or written within the class body.\n By defining things that are not visible outside of the class, you ensure that your classes' users can't depend on internals, which may change from version to version.\n
When a static or instance method is called without a value for this, such as by assigning the method to a variable and then calling it, the this value will be undefined inside the method. This behavior is the same even if the \"use strict\" directive isn't present, because code within the class body is always executed in strict mode.
Only single inheritance is allowed in C#. In other words, a class can inherit implementation from one base class only. However, a class can implement more than one interface. The following table shows examples of class inheritance and interface implementation:
The following example demonstrates declaring class fields, constructors, and methods. It also demonstrates object instantiation and printing instance data. In this example, two classes are declared. The first class, Child, contains two private fields (name and age), two public constructors and one public method. The second class, StringTest, is used to contain Main.
Notice that in the previous example the private fields (name and age) can only be accessed through the public method of the Child class. For example, you cannot print the child's name, from the Main method, using a statement like this:
Classes provide a means of bundling data and functionality together. Creatinga new class creates a new type of object, allowing new instances of thattype to be made. Each class instance can have attributes attached to it formaintaining its state. Class instances can also have methods (defined by itsclass) for modifying its state.
(Lacking universally accepted terminology to talk about classes, I will makeoccasional use of Smalltalk and C++ terms. I would use Modula-3 terms, sinceits object-oriented semantics are closer to those of Python than C++, but Iexpect that few readers have heard of it.)
Class definitions, like function definitions (def statements) must beexecuted before they have any effect. (You could conceivably place a classdefinition in a branch of an if statement, or inside a function.)
then MyClass.i and MyClass.f are valid attribute references, returningan integer and a function object, respectively. Class attributes can also beassigned to, so you can change the value of MyClass.i by assignment.__doc__ is also a valid attribute, returning the docstring belonging tothe class: "A simple example class".
As discussed in A Word About Names and Objects, shared data can have possibly surprisingeffects with involving mutable objects such as lists and dictionaries.For example, the tricks list in the following code should not be used as aclass variable because just a single list would be shared by all Doginstances:
Often, the first argument of a method is called self. This is nothing morethan a convention: the name self has absolutely no special meaning toPython. Note, however, that by not following the convention your code may beless readable to other Python programmers, and it is also conceivable that aclass browser program might be written that relies upon such a convention.
Any function object that is a class attribute defines a method for instances ofthat class. It is not necessary that the function definition is textuallyenclosed in the class definition: assigning a function object to a localvariable in the class is also ok. For example:
The name BaseClassName must be defined in a scope containing thederived class definition. In place of a base class name, other arbitraryexpressions are also allowed. This can be useful, for example, when the baseclass is defined in another module:
Execution of a derived class definition proceeds the same as for a base class.When the class object is constructed, the base class is remembered. This isused for resolving attribute references: if a requested attribute is not foundin the class, the search proceeds to look in the base class. This rule isapplied recursively if the base class itself is derived from some other class.
Derived classes may override methods of their base classes. Because methodshave no special privileges when calling other methods of the same object, amethod of a base class that calls another method defined in the same base classmay end up calling a method of a derived class that overrides it. (For C++programmers: all methods in Python are effectively virtual.)
An overriding method in a derived class may in fact want to extend rather thansimply replace the base class method of the same name. There is a simple way tocall the base class method directly: just call BaseClassName.methodname(self,arguments). This is occasionally useful to clients as well. (Note that thisonly works if the base class is accessible as BaseClassName in the globalscope.)
For most purposes, in the simplest cases, you can think of the search forattributes inherited from a parent class as depth-first, left-to-right, notsearching twice in the same class where there is an overlap in the hierarchy.Thus, if an attribute is not found in DerivedClassName, it is searchedfor in Base1, then (recursively) in the base classes of Base1,and if it was not found there, it was searched for in Base2, and so on.
Dynamic ordering is necessary because all cases of multiple inheritance exhibitone or more diamond relationships (where at least one of the parent classescan be accessed through multiple paths from the bottommost class). For example,all classes inherit from object, so any case of multiple inheritanceprovides more than one path to reach object. To keep the base classesfrom being accessed more than once, the dynamic algorithm linearizes the searchorder in a way that preserves the left-to-right ordering specified in eachclass, that calls each parent only once, and that is monotonic (meaning that aclass can be subclassed without affecting the precedence order of its parents).Taken together, these properties make it possible to design reliable andextensible classes with multiple inheritance. For more detail, see 041b061a72