Embedded Concepts

Question 1

RAII

Answer 1

Resource Acquisition Is Initialization.
Resource acquired in constructor, released in destructor.
Ex: unique_ptr, shared_ptr, scoped_lock, open file in constructor, close in destructor.
Items constructed on the stack or items with auto-lifetime management (smart pointers etc..)

Question 2

RAII addresses which aspect of C++?

Answer 2

Exceptions.

Question 3

Dependency Injection

Answer 3

Inject via constructor arguments the resources a class depends on.
So the creator of Foo managed the creation and insertion of Foo’s dependencies.
Allows easy mocking, testing etc…
Factory Method works with this.

Question 4

TDD

Answer 4

Test Driven Development.

1. Write a test case - fails to compile with no source.
2. fill out basic source to compile, but still fails.
3. fill out basic implementation to pass.
4. refactor to best implementation.

Question 5

Singleton Pattern C++ Implementation

Answer 5

class S
{
public:
// public getter returning single static instance
  static S& getinstance()
  {
    static S instance;
    return S;
  }
private:
// private constructor, copy constructor & assignment
  S(){}
  S(S const&);
  void operator=(S const&);
public:
// public deleted functions (good style)
  s(S const&) = delete;
  void operator=(S const&) = delete;

Question 6

Singleton Pattern

Answer 6

Single instance in system.
Hide constructor so only accessible by itself.
Static (globally accessible) method to get instance.

Question 7

Adapter Pattern

Answer 7

Make class/interface compatible with another class or interface.
Adapter class can own adaptee class and make calls.
ex: Lm75Ctrl and Lm75CtrlAdapter - just extends the interface of Lm75Ctrl to implement ITempSensor.

Question 8

Factory Method/Abstract Factory Pattern

Answer 8

Class or code doesn’t need to know HOW to create objects - or even what kind it will get.
Just calls factory::create_x().