Modular programming is a software design technique that emphasizes separating the functionality of a program into independent, interchangeable modules. Each module contains everything necessary to execute only one aspect of the desired functionality. This approach enhances code readability, maintainability, and reusability.

1. Modularity: Breaking down a program into smaller, manageable, and independent modules.
2. Encapsulation: Each module should encapsulate its data and functions, exposing only what is necessary.
3. Reusability: Modules should be designed to be reusable across different parts of the program or even in different programs.
4. Separation of Concerns: Each module should address a specific concern or functionality, reducing complexity.

• Improved Readability: Smaller, well-defined modules are easier to read and understand.
• Easier Maintenance: Bugs can be isolated and fixed within individual modules without affecting the entire program.
• Enhanced Collaboration: Multiple developers can work on different modules simultaneously.
• Reusability: Modules can be reused in different programs, saving development time.

In MUMPS, modules can be implemented using routines. Each routine can be considered a module that performs a specific task.

Let's create a simple example where we have separate modules for addition, subtraction, multiplication, and division.

Addition Module

Subtraction Module

Multiplication Module

Division Module

We can create a main routine that uses these modules to perform arithmetic operations.

• ADD, SUB, MUL, DIV: These are our modules (routines) that perform specific arithmetic operations.
• MAIN: This is the main routine that calls the modules and displays the results.

Task: Create a modular program in MUMPS that includes modules for calculating the area and perimeter of a rectangle.

1. Area Module: Create a module to calculate the area of a rectangle.
2. Perimeter Module: Create a module to calculate the perimeter of a rectangle.
3. Main Routine: Create a main routine that uses these modules to calculate and display the area and perimeter of a rectangle with given length and width.

Area Module

Perimeter Module

Main Routine

• AREA: This module calculates the area of a rectangle.
• PERIMETER: This module calculates the perimeter of a rectangle.
• MAIN: This routine sets the length and width of the rectangle, calls the AREA and PERIMETER modules, and displays the results.

• Mistake: Forgetting to use QUIT to return the result from a module.
  • Tip: Always ensure your module ends with a QUIT statement to return the result.
• Mistake: Not encapsulating data within modules.
  • Tip: Use NEW to localize variables within routines to avoid unintended side effects.

Modular programming in MUMPS involves creating independent routines that perform specific tasks. This approach enhances code readability, maintainability, and reusability. By breaking down a program into smaller modules, you can manage complexity more effectively and develop more robust and scalable applications.