Properties Overview

Properties Overview

What is a Property? Read only Properties Write only Properties Properties with Validation Interface Properties Abstract Properties Static Properties Auto-Implemented Properties

Auto-Implemented Properties

We have seen many types of properties so far, you would have notices that defining a simple get/set property involves many lines of code. A simple private variable with a public property definition needs about 10 lines of code, if this is the case then complex class with many properties will have hundreds of lines of code. Auto Implemented properties help us to overcome this by simplifying property definition of simple properties.

Auto-Implemented Properties were introduced in .Net 3.0 to simplify property definition; the following example defines a 2 auto implemented properties Name and Age with just 2 lines of code.

Static Properties

Static members of a class are those which can be accessed without creating an instance of the containing class, similarly static properties can be assessed directly by prefixing the property name with the class name and a dot (.). Static properties should have the keyword static mentioned in their definition.

In the following example we will define a static property and access the same directly without creating an instance of the class.

Abstract Properties

Abstract Properties are similar to Interface Properties, Abstract Properties are those which are defined in an Abstract class, similar to Interface Properties they do not have any definition, we just need to define the get {} and/or set {} accessors.

The class which inherits the abstract class will use the property and define the get {} and/or set {} accessors in the derived class.

The following example defines an abstract class with an abstract property.

Interface Properties

Interface properties are those which are defined in the interface and implemented in the class which implements the interface. Interface properties do not have a definition, they just specify the name of the property and its accessibility Read-Write, or Read-Only or Write-Only.

The following example defines an Interface Property Name in the interface IEmployee

Properties with Validation

In general properties have a get {} and set {} accessor which is used to get and set the values of the underlying private member in the class, these properties just make sure that the values which is being set from the external source matches the expected data type of the underlying private member. Apart from this they do not perform any other validation.

There are specific where the value to be set to a private member should satisfy certain business validations, since the member is private there is no way to set the value directly from external sources, the only way to set a value to the member is through the set {} accessor, we can perform a set of validations in the set {} accessor before assigning values to the variable.

In the following example we impose a simple validation to the UserName property, the value assigned to the property should be a string of length greater than or equal to 8, else an exception should be thrown.

Write only Properties

As the name suggests write-only properties are those which can be assigned from external classes but the value cannot be read from any external class.

In general a property has get {} and set {} accessors, to create a write-only property we just need to define the set {} accessor for the property without the get {} accessor.

The following example defines a write-only property for the private variable strName

Read only Properties

As the name suggests read-only properties are those which can be consumed by external classes but cannot be reset by any operation external to the class.

In general a property has get {} and set {} accessors, to create a read-only property we just need to define the get {} accessor for the property without the set {} accessor.

The following example defines a read-only property for the private variable strName

What is a Property?

Object oriented programming languages support encapsulation, which is also called as data hiding. Encapsulation is hiding the private variables of a class from the external world, if we are hiding the members then how do we get and set the values of these members? It is when Properties become significant.

Properties define get and set assessors which can be used to get and set values of private variables in a class.