How Can Dependency Injection Solve External Variable Access Issues in a Pagination Class?

Utilizing External Variables Within a Class Using Dependency Injection

When attempting to implement a pagination class, you may encounter errors when accessing external variables, such as a database connection, from within the class. To address this issue, two approaches can be employed: global declaration or dependency injection.

Global Declaration

Using the global keyword allows you to access external variables within a function or class. However, this approach has several drawbacks:

• Hidden Dependencies: It makes it difficult to identify the dependencies of a function or class, as the external variable is not explicitly declared.
• Tight Coupling: It tightly couples the function or class to a specific implementation of the external variable, making it difficult to change or test.

Dependency Injection

Dependency injection involves injecting the required object into the constructor or method that uses it. This approach offers several advantages:

• Explicit Dependencies: It clearly specifies the dependencies of a function or class, making it easy to identify and understand the code.
• Loose Coupling: It loosely couples the function or class to its dependencies, making it easy to switch between different implementations.
• Enhanced Testability: It enables unit testing of a function or class without relying on external dependencies, as mocked dependencies can be easily injected.

Injecting the database object into the pagination class through its constructor allows us to access the database connection from within the class without declaring it as global. This ensures explicit dependencies, loose coupling, and enhanced testability for our pagination class.

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