Gain insights into software design patterns in C, explore their implementation, discover underlying principles, and learn to build a vocabulary for better communication and coding practices.

c.tar.gz

main+customer.c

main+customer.c-copy

watches

customers

observer

Reactor

Reactor-copy

observer-copy

Software design patterns are a valuable tool in any software developer's skill set. However, most design patterns are described in the context of an object-oriented programming language such as C++ or Java. The C language is sadly absent in the pattern literature. This course is here to change that by demonstrating that it is possible to use patterns in C programs and how it adds benefits to C programmers. You will learn why design patterns are more of a communication tool than technical solutions, and how patterns let you build and share a common vocabulary that simplifies communication.

The course presents a number of patterns and explains how to implement them in C. Each pattern is introduced via the problem it solves and the domains where the pattern can be used. We also discuss the underlying design principles as well as the trade-offs when applying the pattern. Finally, the course covers a set of coding idioms that will guide you when applying design patterns in C.

Software Design Patterns in C

In the C language, generality is usually spelled ```void*```. This is reflected in the standard library. For example,
the functions for dynamic memory allocation (```malloc```, ```calloc```, and ```realloc```) do not know anything about the types we are allocating storage for and return pointers to allocated storage as ```void*```. The client has
to provide the required size information to the allocation functions. Here’s an example with ```malloc```:

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

typedef struct HelloTelegram
{
  const char* text;
  const char* username;
  int code;
} HelloTelegram;

int main() {
    HelloTelegram* telegram = malloc(sizeof(HelloTelegram));
    printf("%lu\n", sizeof(telegram));
    printf("%lu\n", sizeof(HelloTelegram));
    return 0;
}


Code like this is sneaky to maintain. As long as the telegram stays as a ```HelloTelegram```, everything
is fine. The sneakiness lies in the fact that the ```malloc``` usage above contains a subtle form of dependency;
the size given must match the size of the type on the left side of the assignment. Consider a change in
telegram type to a ```GoodByeTelegram```. With the code above, this means a change in two places, which is at
least one change too much:

In this lesson, we will briefly explain the sizeof to variables.



SIZEOF TO VARIABLES

In this lesson, we will briefly explain the sizeof to variables.

Introduction to Pattern in C

The First-Class ADT Pattern

The State Pattern

The Strategy Pattern

The Observer Pattern

The Reactor Pattern

Idiomatic Expressions

Conclusion

SIZEOF TO VARIABLES

Problem Context