-% Motivate! (coupling)
-% Rework examples
% Law of demeter?
\documentclass[USenglish,9pt]{beamer}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{babel,textcomp}
-\usepackage[style=alphabetic,backend=biber]{biblatex}
+\usepackage[style=alphabetic,backend=biber,doi=false,isbn=false]{biblatex}
\usepackage{babel,textcomp,csquotes}
\usepackage{xspace}
\begin{frame}
\frametitle{Refactoring, as defined in the literature}
- In his book on refactoring\citing{refactoring}, Martin Fowler defines a
- refactoring like this:
\begin{quote}
\emph{Refactoring} (noun): a change made to the internal structure
\begin{frame}
\frametitle{An alternative definition of refactoring}
- If we leave the motivation behind refactoring out of the definition, it could
- be rephrased like this:
\begin{definition}
A \emph{refactoring} is a transformation
\end{frame}
\begin{frame}
- \frametitle{Composite refactorings}
- \emph{Primitive refactorings} are refactorings that cannot be expressed in
- terms of other refactorings. From these, we can express \emph{composite
- refactorings}:
+ \frametitle{Primitive and composite refactorings}
+ \begin{definition}
+ A \emph{primitive refactoring} is a refactoring that cannot be expressed in
+ terms of other refactorings.
+
+ \end{definition}
\begin{definition}
A \emph{composite refactoring} is a refactoring that can be expressed in
\begin{itemize}
\item Get rid of long navigation paths.
\item Move operations closer to the data they manipulate.
- \item Eliminate coupling.
+ \item Reduce coupling.
+ \item Increase maintainability.
\end{itemize}
\begin{frame}[fragile]
\frametitle{The Extract Method refactoring}
- The \refa{Extract Method} refactoring is used to extract a fragment of code
- out of its context and into a new method. A call to this new method is inlined
- where the fragment was before. The refactoring is used to break code into
- logical units, with names that explain their purpose.
+ Extract a fragment of code into a new method.
\def\charwidth{4.5pt}
\def\indent{2*\charwidth}
\vfill
\end{minipage}
-% \begin{multicols}{2}
-% \begin{minted}[samepage]{java}
-% class C {
-% void method() {
-% // 1: Some code
-% // 2: Fragment
-% // 3: More code
-% }
-% }
-% \end{minted}
-%
-% \columnbreak
-%
-% \begin{minted}[samepage]{java}
-% class C {
-% void method() {
-% // 1: Some code
-% extractedMethod();
-% // 3: More code
-% }
-%
-% void extractedMethod() {
-% // 2: Fragment
-% }
-% }
-% \end{minted}
-% \end{multicols}
-
\end{frame}
+
\begin{frame}[fragile]
\frametitle{The Move Method refactoring}
- The \refa{Move Method} refactoring is used to move a method from one class to
- another. This is useful if a method is using more features of another class
- than of the class which it is currently defined.
+ Move a method from one class to another.
\def\charwidth{4.5pt}
\def\indent{2*\charwidth}
\end{minted}
\vfill
\end{minipage}
-
-% \begin{multicols}{2}
-% \begin{minted}[samepage]{java}
-% class C {
-% void method() {
-% X x = new X();
-% iBelongInX(x);
-% }
-% void iBelongInX(X x) {
-% x.foo(); x.bar();
-% }
-% }
-%
-% class X {
-% void foo(){/*...*/}
-% void bar(){/*...*/}
-% }
-% \end{minted}
-%
-% \columnbreak
-%
-% \begin{minted}[samepage]{java}
-% class C {
-% void method() {
-% X x = new X();
-% x.iBelongInX();
-% }
-% }
-%
-% class X {
-% void iBelongInX() {
-% foo(); bar();
-% }
-% void foo(){/*...*/}
-% void bar(){/*...*/}
-% }
-% \end{minted}
-% \end{multicols}
\end{frame}
+
\mysection{The Extract and Move Method refactoring}
\begin{frame}[fragile]
\end{frame}
\begin{frame}
+ \def\secondlevelmark{\textbullet}
\begin{itemize}
\item Composed of \ExtractMethod and \MoveMethod.
- \item Conseptually, one ``atomic'' operation.
+ \item Conceptually, one ``atomic'' operation.
+ \vspace{2.5pt}
+ \item Implemented as an Eclipse plugin.
+ \vspace{2pt}
+ \begin{itemize} \itemsep3pt
+ \item[\secondlevelmark] The primitive refactorings are supplied by the
+ Eclipse JDT.
+ \item[\secondlevelmark] The composition work had to be done by us.
+ \item[\secondlevelmark] Not seamless (find the extracted method, move
+ target etc.).
+
+ \end{itemize}
\end{itemize}
\mysection{Automating the refactoring}
-\begin{frame}
+\begin{frame}[fragile]
For any given method: We want to find the best candidate for the
- \ExtractAndMoveMethod refactoring.
+ \ExtractAndMoveMethod refactoring, if any exist.
+
+ \begin{minipage}[b]{0.33\textwidth}
+ \hfill\vspace{0.5cm}
+ \end{minipage}\begin{minipage}[t]{0.5\textwidth}
+\def\charwidth{4.5pt}
+\def\indent{2*\charwidth}
+\def\rightColX{32*\charwidth*0}
+\def\lineheight{\baselineskip}
+\def\mintedtop{6.5pt}
- % TODO illustrative picture
+\begin{tikzpicture}[overlay, yscale=-1]
+ \tikzstyle{overlaybox}=[fill=gray,opacity=0.2]
+ \draw[overlaybox] (0,\mintedtop+\lineheight*3) rectangle
+ +(16*\charwidth,2*\lineheight);
+
+ \node[draw opacity=0, text=red] at (20*\charwidth,\mintedtop+\lineheight*4)
+ {\fontsize{40}{60}\selectfont ?};
+\end{tikzpicture}
+\begin{minted}[samepage]{java}
+void method() {
+ statement_1;
+ statement_2;
+ statement_3;
+ statement_4;
+ statement_5;
+}
+\end{minted}
+ \end{minipage}
\end{frame}
-\begin{frame}
- \frametitle{The refactoring is search-based}
- The search is based on heuristics, not metrics.
+\begin{frame}[fragile]
+\begin{minipage}[t]{0.5\textwidth}
+\def\charwidth{4.75pt}
+\def\indent{2*\charwidth}
+\def\lineheight{\baselineskip}
+\def\mintedtop{5.8pt}
+
+\begin{tikzpicture}[overlay, yscale=-1]
+ \tikzstyle{overlaybox}=[fill=gray,opacity=0.2]
+ \draw[overlaybox] (2*\indent,\mintedtop+12*\lineheight) rectangle
+ +(14*\charwidth,2*\lineheight);
+
+ \draw[overlaybox] (9*\charwidth,\mintedtop+\lineheight) rectangle
+ +(\charwidth,\lineheight);
+
+ \node[draw opacity=0, text=red] at (12.1*\indent,\mintedtop+12.9*\lineheight)
+ {text selection};
+
+ \node[draw opacity=0, text=red] at (11.5*\indent,\mintedtop+4*\lineheight)
+ {move target};
+
+ \draw[-latex,red] (11.5*\indent-5*\charwidth,\mintedtop+3.7*\lineheight) --
+ (10.2*\charwidth,\mintedtop+1.5*\lineheight);
+
+\end{tikzpicture}
+\begin{minted}[linenos,samepage]{java}
+class C {
+ A a; B b; boolean bool;
+ void method(int val) {
+ if (bool) {
+ a.foo();
+ a = new A();
+ a.bar();
+ }
+ a.foo();
+ a.bar();
+ switch (val) {
+ case 1:
+ b.a.foo();
+ b.a.bar();
+ break;
+ default:
+ a.foo();
+ }
+ }
+}
+\end{minted}
+\end{minipage}\begin{minipage}[t]{0.5\textwidth}
+ \pause
+ \vspace{1.2cm}
+ A \textbf{candidate} consists of a \emph{text selection} and a \emph{move
+ target}.\\~\\
+
+ A \textbf{valid text selection} is a text selection that contains all of one
+ or more consecutive program statements. It is the input to the \ExtractMethod
+ refactoring.\\~\\
+
+ A \textbf{move target} is a variable (local or field), whose type is the
+ destination class in the \MoveMethod refactoring.
+
+\end{minipage}
+
\end{frame}
+
\begin{frame}
- \frametitle{The search space}
+ \frametitle{Searching}
+ Usually, search-based refactoring is based on metrics.
\begin{itemize}
- \item All possible selections of statements in a method.
- \item Disqualifying illegal selections (avoiding problems).
-
+ \item Refactor a lot.
+ \item Choose the best candidate based on measurements.
+ \end{itemize}\\~\\
+
+ Our refactoring is based on heuristics.
+ \begin{itemize}
+ \item Up-front analysis.
+ \item A set of assumptions defining what is considered the best candidate.
+ \item No need to actually perform changes (before deciding).
+ \item Search through all valid selections to find the best candidate.
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Choosing a refactoring candidate}
\begin{itemize}
- \item Find the best move target for all selections.
- \item Choose the best candidate between the selections.
+ \item Search through all selections to find the possible candidates.
+ \item Find the best move target for all the candidates.
+ \item Choose the best among the possible candidates.
+ \item Based on the lengths of the navigation paths and the occurrence
+ counts.
\end{itemize}
\end{frame}
-\begin{frame}
- \frametitle{Finding a move target for a selection}
-
- \begin{itemize}
- \item Find possible move targets (prefixes).
- \item Find the prefixes not suitable as move targets (unfixes).
- \item Find the best move target among the suitable targets (prefixes minus
- unfixes).
-
- \end{itemize}
-
-\end{frame}
-
\mysection{Demonstration}
-\mysection{Is it any good?}
+\mysection{Case studies}
\begin{frame}
- \frametitle{Case studies performed}
- Performed on the \code{org.eclipse.jdt.ui} and \code{no.uio.ifi.refaktor}
- projects. The resulting code was analyzed with
+ Case studies performed on the \code{org.eclipse.jdt.ui} and
+ \code{no.uio.ifi.refaktor} projects. The resulting code was analyzed with
SonarQube.
\vspace*{\baselineskip}
The Eclipse JDT UI project:
\begin{itemize}
\item Over 300,000 lines of code.
- \item 2,552 methods out of 27,667 methods chosen to be refactored
+ \item 2,552 methods out of 27,667 methods chosen to be refactored.
\item Approx. 100 minutes.
\end{itemize}
\begin{itemize}
\item Measurements show some deterioration regarding coupling.
\item All improvement not measured, only strict coupling between classes.
- \item Examples exists where coupling is improved.
- \item More examples exists where dependencies are introduced.
+ \item Examples exist where coupling is improved.
+ \item More examples exist where dependencies are introduced.
\end{itemize}
\end{frame}
\mysection{Conclusions}
\begin{frame}
- \frametitle{Conclusions}
\begin{itemize}
\item Automation is possible.
\item Efficient enough for some kinds of use.
\end{itemize}
\end{frame}
+\mysection{Future work}
+\begin{frame}
+\begin{itemize}
+ \item Complete analysis.
+ \item Make refactoring safer.
+ \item Improve heuristics to avoid introducing new dependencies.
-%\begin{frame}
-% \frametitle{Demonstration}
-% \begin{itemize}
-% \item {The
-% \code{LastStatementOfSelectionEndsInReturnOrThrow\-Checker.visit(IfStatement
-% node)} method}
-% \begin{itemize}
-% \item Extract and Move on selection
-% \item Extract and Move, search based, on method
-% \end{itemize}
-% \item The \code{no.uio.ifi.refaktor} project
-% \begin{itemize}
-% \item Extract and Move, search based, over whole project
-% \end{itemize}
-% \end{itemize}
-%
-%\end{frame}
-
-
-%\begin{frame}
-% \frametitle{What is left}
-% \begin{itemize}
-% \item Write technical section
-% \item Write up argument for correctness
-% \item Define the final case study
-% \item Run unit tests before and after change
-% \item Make more examples
-% \item Metrics?
-% \item \ldots
-% \end{itemize}
-%
-%\end{frame}
-
-\mysection{The end.}
+\end{itemize}
+\end{frame}
\begin{frame}
\frametitle{References}
git://git.uio.no / ifi-stolz-refaktor.git / blobdiff