Opaque Method Design Pattern

In the embedded systems programming, an opaque pattern is often used to hide the implementation details of a data structure or module from the outside world. This helps in encapsulating the internal details, providing a clean interface, and enhancing code maintainability.

The basic idea is to declare a structure in the source file that contains the implementation details, and then provide a header file with only the necessary information for using the module.

Problem Statement of Opaque Method Design Pattern

Let’s see the simple example of how we might use an opaque pattern in embedded C:Suppose we want to create a module for handling a temperature sensor, and we wants to keep the details of the sensor structure hidden from the external code.

temperature_sensor.h (Public header file):

C

// temperature_sensor.h
 
#ifndef TEMPERATURE_SENSOR_H
#define TEMPERATURE_SENSOR_H
 
// Forward declaration of the opaque structure
typedef struct TemperatureSensor TemperatureSensor;
 
// Function prototypes
TemperatureSensor* temperature_sensor_create(void);
void temperature_sensor_destroy(TemperatureSensor* sensor);
float temperature_sensor_read(TemperatureSensor* sensor);
 
#endif // TEMPERATURE_SENSOR_H

temperature_sensor.c (Private implementation file):

C

// temperature_sensor.c
 
#include "temperature_sensor.h"
 
// Define the actual structure of the TemperatureSensor
struct TemperatureSensor {
    // Include whatever internal data members are necessary
    float last_reading;
    // ... other members
};
 
TemperatureSensor* temperature_sensor_create(void) {
    TemperatureSensor* sensor = malloc(sizeof(TemperatureSensor));
    if (sensor != NULL) {
        // Initialize internal data members as needed
        sensor->last_reading = 0.0;
        // ... other initialization
    }
    return sensor;
}
 
void temperature_sensor_destroy(TemperatureSensor* sensor) {
    free(sensor);
}
 
float temperature_sensor_read(TemperatureSensor* sensor) {
    // Simulate reading from the sensor
    // In a real implementation, this would involve interacting with the hardware
    // Here, we'll just return a dummy value for demonstration purposes
    sensor->last_reading += 0.5;  // Simulating an incremental increase
    return sensor->last_reading;
}

Explanation of above Code:

By the help of this Process, external code can include temperature_sensor.h and use the functions declared in the header file without knowing the details of the TemperatureSensor structure.
The actual implementation details are hidden in the temperature_sensor.c file, providing a clean separation between the interface and the implementation.

Design Patterns for Embedded Systems in C

When working with embedded systems in C, there are so many design patterns that are particularly very useful. Many design patterns can be applied to embedded systems development in C. In this article, we will discuss design patterns for Embedded Systems in C, let’s see all of them one by one with the help of examples.

Important Topics for Design Patterns for Embedded Systems in C

What is a Design Pattern?
Creational Design Patterns for Embedded Systems in C
- Factory Method Design Pattern
- Object Method Design Pattern
- Opaque Method Design Pattern
- Singleton Method Design Pattern
Structural Design Patterns for Embedded Systems in C
- Callback Method Design Patterns
- Inheritance Method Design Pattern
- Virtual API Method Design Pattern
Other Design Patterns for Embedded System in C
- Bridge Method Design Pattern
- Concurrency Method Design Pattern
- Spinlock Method Design Pattern
- Mutex Method Design Pattern
- Conditional Method Design Pattern
- Behavioral Method Design Pattern

Opaque Method Design Pattern

C

C

Explanation of above Code:

Design Patterns for Embedded Systems in C

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