CODESAMPLE

Facade - C

Facade C

The Facade pattern provides a simplified interface to a complex subsystem. It encapsulates multiple interactions within the subsystem into a single, higher-level interface, making the system easier to use. This example demonstrates a media player facade, hiding the complexities of audio and video components. The MediaPlayerFacade provides methods like play() and stop() which internally handle the initialization, playback, and cleanup of the underlying AudioPlayer and VideoPlayer subsystems. This is idiomatic C as it leverages structs to represent the facade and subsystems, and function pointers to define the interfaces, keeping the code modular and manageable.

#include <stdio.h>
#include <stdlib.h>

// Subsystem 1: Audio Player
typedef struct {
    void (*start)(void);
    void (*stop)(void);
} AudioPlayer;

void audio_start(void) {
    printf("Audio: Starting playback...\n");
}

void audio_stop(void) {
    printf("Audio: Stopping playback...\n");
}

AudioPlayer audio_player = {
    .start = audio_start,
    .stop = audio_stop
};

// Subsystem 2: Video Player
typedef struct {
    void (*start)(void);
    void (*stop)(void);
} VideoPlayer;

void video_start(void) {
    printf("Video: Starting playback...\n");
}

void video_stop(void) {
    printf("Video: Stopping playback...\n");
}

VideoPlayer video_player = {
    .start = video_start,
    .stop = video_stop
};

// Facade: Media Player
typedef struct {
    AudioPlayer *audio;
    VideoPlayer *video;
} MediaPlayerFacade;

void media_player_start(MediaPlayerFacade *facade) {
    if (facade == NULL) return;
    facade->audio->start();
    facade->video->start();
}

void media_player_stop(MediaPlayerFacade *facade) {
    if (facade == NULL) return;
    facade->audio->stop();
    facade->video->stop();
}

MediaPlayerFacade create_media_player_facade() {
    MediaPlayerFacade facade;
    facade.audio = &audio_player;
    facade.video = &video_player;
    return facade;
}

int main() {
    MediaPlayerFacade player = create_media_player_facade();

    media_player_start(&player);
    // Simulate playback
    printf("Playing media...\n");
    media_player_stop(&player);

    return 0;
}