git.tex

\section[Git]{Using git for your own work}
\frame{\tableofcontents[currentsection,hideothersubsections]}

\subsection{Git basics}
\begin{frame}
  \frametitle{Revision control systems}
  \begin{itemize}
  \item Allow you to regularly archive your work
    \begin{itemize}
    \item You can retrieve a previous status if you made a mistake
    \end{itemize}
  \item Allow you to store your work on an external server
    \begin{itemize}
    \item No big damage if your hard disk crashes
    \end{itemize}
  \item Organize your work between several computers
    \begin{itemize}
    \item No question which version is the latest
    \end{itemize}
  \end{itemize}
\end{frame}

\begin{frame}
  \frametitle{Some revision control systems}
  \begin{itemize}
  \item RCS, CVS
    \begin{itemize}
    \item grandparents enjoying retirement
    \end{itemize}
  \item SVN
    \begin{itemize}
    \item Long time favorite with server infrastructure
    \end{itemize}
  \item Git
    \begin{itemize}
    \item Very powerful and flexible
    \item Easy server setup
    \item Public servers avaliable
      \begin{itemize}
      \item Github
      \item Bitbucket: free private repositories with university email address
      \end{itemize}
    \end{itemize}
  \item Mercurial
  \end{itemize}
\end{frame}


\begin{frame}[fragile]
  \frametitle{The lonely git cycle}
  \begin{block}{First time only}
    \begin{lstlisting}[language=bash]
git clone repository-address
    \end{lstlisting}
    \end{block}
    \begin{block}{Everytime before you start something new}
    \begin{lstlisting}[language=bash]
git pull
    \end{lstlisting}      
    \end{block}
    \begin{block}{Everytime you finish something}
      \begin{lstlisting}[language=bash]
git commit -am 'message'
git push
     \end{lstlisting}
    \end{block}
    
Pushing more than hourly is not a bad idea
\end{frame}

\begin{frame}[fragile]
  \frametitle{Other important commands}
    \begin{block}{}
    \begin{lstlisting}[language=bash]
git status
    \end{lstlisting}      
    \end{block}
    \begin{itemize}
    \item Modified files that need commit
    \item Untracked files that may need add
    \item Your directory is ahead of origin and needs push
    \end{itemize}

    \begin{block}{}
    \begin{lstlisting}[language=bash]
git add filename
    \end{lstlisting}      
    \end{block}
    \begin{itemize}
    \item Add a newly created file to the repository
    \end{itemize}
\end{frame}

\begin{frame}
  \frametitle{Notes on commit}
  \begin{itemize}
  \item Commits are atoms
    \begin{itemize}
    \item They constitute an inseparable logical unit
    \item They define stages and steps in your development
    \end{itemize}
  \item Keep commits constrained to single issues
    \begin{itemize}
    \item If you change two separate issues in your code, commit them
      separately!
    \item Provide short, but meaningful commit messages
    \end{itemize}
  \item Commits work by comparing text line by line
    \begin{itemize}
    \item Keep reformatting to a minimum
    \end{itemize}
  \end{itemize}
\end{frame}

\subsection{Git for collaboration}
\frame{\tableofcontents[currentsection,subsectionstyle=show/shaded/hide]}

\begin{frame}[fragile]
  \frametitle{Special rules for big collaborations}
  \begin{itemize}
  \item Create your own branch for development
    \begin{block}{}
    \begin{lstlisting}[language=bash]
git checkout -b my_branch
    \end{lstlisting}      
    \end{block}
    \item Regularly update your master branch
    \begin{block}{}
    \begin{lstlisting}[language=bash]
git checkout master
git pull
    \end{lstlisting}      
    \end{block}
    \item Keep your branch current
    \begin{block}{}
    \begin{lstlisting}[language=bash]
git checkout my_branch
git rebase master
git push -f
    \end{lstlisting}      
    \end{block}
    Warning: rebase and the '-f' rewrite history. Only do this on
    your own branch!
    \item When your development has converged
    \begin{block}{}
    \begin{lstlisting}[language=bash]
git checkout master
git merge my_branch
git push
    \end{lstlisting}      
    \end{block}
  \end{itemize}
\end{frame}

\begin{frame}
  \begin{alertblock}{Warning!!!}
    Never edit the master branch of a busy repository!
  \end{alertblock}
\end{frame}

\begin{frame}[fragile]
  \frametitle{Conflict resolution}
  \begin{itemize}
  \item Commit, merge and rebase are based on line-by-line text comparison
  \item Sometimes, two people edited the same lines
    \begin{itemize}
    \item Git cannot determine which update should persist
    \end{itemize}
  \item You will be informed of a conflict and must resolve it before
    continuing
    \begin{itemize}
    \item Blocks of text of the form
\begin{verbatim}
<<<<<<< HEAD
text somebody else committed
=======
text I committed
>>>>>>> Last commit comment
\end{verbatim}
    \item Make up your mind on the best solution
    \begin{block}{}
    \begin{lstlisting}[language=bash]
git add fixed_file
git rebase --continue
    \end{lstlisting}      
    \end{block}
    \end{itemize}
  \end{itemize}
\end{frame}
\begin{frame}
  \frametitle{Forking a repository}
  \begin{itemize}
  \item When you push your branch to a joint repository, it becomes
    available to everybody
  \item Forking a repository
    \begin{itemize}
    \item Supported by Github and Bitbucket
    \item Creates your own copy on the same server
    \item Nobody cares what you push
    \item Bitbucket allows synchronization by pressing a button
    \end{itemize}
  \item Pull requests
    \begin{itemize}
    \item Branches can be submitted by pressing a button on the web site
    \item Pull requests provide a good interface for code review
    \item They put a barrier on sneaking in unwanted changes
    \end{itemize}
  \end{itemize}
\end{frame}

\begin{frame}
  \begin{alertblock}{Warning!!!}
    Even if you have your own fork: never edit the master branch of a
    busy repository!
  \end{alertblock}
\end{frame}


\subsection{Problems}
\input{exercises/git}


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