static.tex

\subsection[static]{Static members}

\begin{frame}[fragile]
  \frametitlecpp[98]{Static members}
  \begin{block}{Concept}
    \begin{itemize}
    \item members attached to a class rather than to an object
    \item usable with or without an instance of the class
    \item identified by the \cppinline{static} keyword
    \end{itemize}
  \end{block}

  \vspace{-1\baselineskip}
  \begin{overprint}
  \onslide<1>
  \begin{exampleblock}{Static.hpp}
  \begin{cppcode}
    class Text {
    public:
      static std::string upper(std::string);
    private:
      static int callsToUpper; // add `inline` in C++17
    };
  \end{cppcode}
  \end{exampleblock}

  \onslide<2>
  \begin{exampleblock}{Static.cpp}
  \begin{cppcode}
    #include "Static.hpp"
    int Text::callsToUpper = 0; // required before C++17

    std::string Text::upper(std::string lower) {
      callsToUpper++;
      // convert lower to upper case
      // return ...;
    }
    std::string uppers = Text::upper("my text");
    // now Text::callsToUpper is 1
  \end{cppcode}
  \end{exampleblock}
  \end{overprint}
\end{frame}