Here are resources for basic concepts about c++.

List of lessons

Cheatsheet

Interfaces in C++

In general, interafces don’t exist. You just declare a class with no implementation ( = 0; at the .h file) and let the derived classes (the ones that inherit) actually define the behaviour. An example here. It’s better to use shared pointers and it would look like this:

class Base { ... }
class DerivedAlpha : public Base { ... }   // A is a Base
class DerivedBeta : public Base { ... }   // B is a Base

...

std::shared_ptr<Base> p0 = std::make_shared<Base>(...);
std::shared_ptr<Base> p1 = std::make_shared<DerivedAlpha>(...);
std::shared_ptr<Base> p2;
if (condition)
{
  p2 = std::make_shared<DerivedAlpha>(...);
}
else 
{
  p2 = std::make_shared<DerivedBeta>(...);
}

Tips and Tricks

Quick way to find the type of variable at compile time

Sometimes we use auto or access an internal type. A quick dirty way to get the job done, following this stack overflow post is to define the show_type_abort in the header file:

// -------- define in .h file --------
template<typename T>
void show_type_abort_helper()
{
    return __PRETTY_FUNCTION__; // returning in void functions forces compiler to fail and abort
}
#define show_type_abort(x) show_type_abort_helper< decltype(x) >()


// -------- use in .cpp file like --------
std::vector< int > s{1, 2, 3};
show_type_abort(s);  // usage
show_type_abort(s[0]);  // can be called multiple times

// -------- you get an error message like --------
// test.cpp:7:12: In instantiation of ‘void show_type_abort_helper() [with T = int]’:
//                                                                             ^^^ (the type I want)
// test.cpp:7:12: error: return-statement with a value, in function returning 'void' [-fpermissive]

Todos

  • accessor to database
  • CMakeLists for most projects guide
  • services vs tasks