From 37f9c9335bd827dd833580cfb215698e15efa77b Mon Sep 17 00:00:00 2001
From: Francesco Giacomini <giaco at cnaf dot infn dot it>
Date: Thu, 19 Oct 2017 16:30:38 +0200
Subject: [PATCH] frames.tex
---
frames.tex | 779 +++++++++++++++++++++++++++++++++++------------------
1 file changed, 512 insertions(+), 267 deletions(-)
diff --git a/frames.tex b/frames.tex
index 01c3bee..1bb64f1 100644
--- a/frames.tex
+++ b/frames.tex
@@ -1,5 +1,5 @@
-%\includeonlyframes{current}
+\includeonlyframes{current}
\begin{frame}
\tikz [remember picture,overlay]
@@ -286,7 +286,7 @@ bool less(int n, int m) \{ return n < m; \}\end{codeblock}
\begin{codeblock}
\uncover<1->{std::array<int,3> a = \{123, 456, 789\};}
\uncover<2->{\alert<2>{auto first = a.begin();} // or std::begin(a)}
-\uncover<3->{\alert<3>{auto \alt<14>{\alert{const }}{}last = a.end();}\alt<14>{}{ } // or std::end(a)}
+\uncover<3->{\alert<3>{auto \only<14->{\alert{const }}last = a.end();}\only<-13>{ } // or std::end(a)}
\uncover<4->{while (\alert<4,7,10,13>{first != last}) \{
... \alert<5,8,11>{*first} ...;
\alert<6,9,12>{++first};
@@ -380,7 +380,7 @@ find(Iterator first, Iterator last, const T\& value)
\begin{itemize}
\item Examples
\begin{codeblock}
-std::vector<int> v = { 2, 5, 4, 0, 1 };
+std::vector<int> v = \{ 2, 5, 4, 0, 1 \};
// sort the first half of the vector in ascending order
std::sort(std::begin(v), std::begin(v) + v.size() / 2);
@@ -595,8 +595,8 @@ accumulate(\ldots,
\uncover<2->{class SomeUniqueName \{
\uncover<5->{int v\_;}
public:
- explicit SomeUniqueName(\uncover<5->{int v})
- \uncover<5->{: v\_\{v\}} \{\}
+ \uncover<5->{explicit SomeUniqueName(int v)
+ : v\_\{v\} \{\}}
\alt<-7>{auto}{\alert<8>{int }} operator()\uncover<3->{(int i)
\{ return i + v\uncover<5->{\_}; \}}
\};}
@@ -1171,6 +1171,513 @@ auto s = std::shared\_ptr<FILE>\{
\end{columns}
\end{frame}
+\begin{frame}
+ \begin{itemize}
+ \item Try the code snippets
+ \item C++ and Memory $\rightarrow$ Pointers
+ \item Adapt the previous exercises to use smart pointers
+ \item Starting from \code{dir.cpp}, write code to:
+ \begin{itemize}
+ \item create a smart pointer managing a \code{DIR} resource obtained with
+ the \code{opendir} function call
+ \item associate a deleter to that smart pointer
+ \item implement a function to read the names of the files in that directory
+ \item check if the deleter is called at the right moment
+ \item hide the creation of the smart pointer behind a factory function
+ \item populate a vector of FILEs, properly wrapped in a smart pointer,
+ obtained opening the regular files in that directory
+ \item \ldots
+ \end{itemize}
+ \end{itemize}
+\end{frame}
+
+\section{Move semantics}
+
+\begin{frame}[fragile,label=current]{Copy vs move}
+
+ \begin{columns}
+ \begin{column}{.45\textwidth}
+
+ \begin{codeblock}{\tiny
+class String \{
+ char* s\_;
+ \ldots
+\};}\end{codeblock}
+
+ \begin{codeblock}<1->{\tiny
+String s1\{"Hi!"\};
+\uncover<2->{String s2\{s1\};}}\end{codeblock}
+
+ \uncover<3->{\small
+ \begin{itemize}
+ \item Both \code{s1} and \code{s2} exist at the end
+ \item The ``deep'' copy is needed
+ \end{itemize}
+ }
+
+ \begin{codeblock}<4->{\tiny
+String get\_string() \{ return "Hey"; \}
+String \alert<6>{s3}\{\alert<5>{get\_string()}\}\alert<7>{;}}\end{codeblock}
+
+ \uncover<8->{\small
+ \begin{itemize}
+ \item Only \code{s3} exists at the end
+ \item The ``deep'' copy is a waste
+ \end{itemize}
+ }
+ \end{column}
+
+ \begin{column}{.55\textwidth}
+ \newcommand*{\stackx}{0.}
+ \newcommand*{\heapx}{3.0}
+
+ \begin{tikzpicture}
+ [anchor=south west]
+ \node at (\stackx,0) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=7cm,
+ draw=black,
+ label={90:{\scriptsize stack}}
+ ] {};
+ \node at (\heapx,0) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=7cm,
+ draw=black,
+ label={90:{\scriptsize heap}}
+ ] {};
+ \node at (\heapx-0.1,4.9) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=0.7cm,
+ ] {};
+ \node at (\heapx,5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white
+ ] {\scriptsize\tt Hi!\char`\\0};
+ \node at (\heapx,5) [
+ rectangle,
+ minimum width=.5cm,
+ minimum height=.5cm,
+ draw=black,
+ densely dotted,
+ label={270:{\scriptsize\tt 0x4abc}}
+ ] {};
+ \node at (\stackx-0.1,4.9) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=.7cm,
+ label={180:{\scriptsize\tt s1}},
+ ] {};
+ \node at (\stackx,5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white,
+ ] {\scriptsize\tt 0x4abc};
+ \visible<2->{
+ \node at (\heapx-0.1,3.9) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=0.7cm,
+ ] {};
+ \node at (\heapx,4) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white
+ ] {\scriptsize\tt Hi!\char`\\0};
+ \node at (\heapx,4) [
+ rectangle,
+ minimum width=.5cm,
+ minimum height=.5cm,
+ draw=black,
+ densely dotted,
+ label={270:{\scriptsize\tt 0x4ab0}}
+ ] (r2) {};
+ \node at (\stackx-0.1,3.9) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=.7cm,
+ label={180:{\scriptsize\tt s2}},
+ ] {};
+ \node at (\stackx,4) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white,
+ ] (h2) {\scriptsize\tt 0x4ab0};
+ %\draw[arrow] (h2) -- (r2);
+ }
+ \visible<6->{
+ \node at (\heapx-0.1,2.4) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=0.7cm,
+ ] {};
+ \node at (\heapx,2.5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white
+ ] {\scriptsize\tt Hey\char`\\0};
+ \node at (\heapx,2.5) [
+ rectangle,
+ minimum width=.5cm,
+ minimum height=.5cm,
+ draw=black,
+ densely dotted,
+ label={270:{\scriptsize\tt 0x4aac}}
+ ] {};
+ \node at (\stackx-0.1,2.4) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=.7cm,
+ label={180:{\scriptsize\tt s3}},
+ ] {};
+ \node at (\stackx,2.5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white,
+ ] {\scriptsize\tt 0x4aac};
+ }
+ \visible<5-6>{
+ \node at (\heapx-0.1,1.4) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=0.7cm,
+ ] {};
+ \node at (\heapx,1.5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white
+ ] {\scriptsize\tt Hey\char`\\0};
+ \node at (\heapx,1.5) [
+ rectangle,
+ minimum width=.5cm,
+ minimum height=.5cm,
+ draw=black,
+ densely dotted,
+ label={270:{\scriptsize\tt 0x4aa0}}
+ ] {};
+ \node at (\stackx-0.1,1.4) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=.7cm,
+ ] {};
+ \node at (\stackx,1.5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white,
+ ] {\scriptsize\tt 0x4aa0};
+ }
+ \end{tikzpicture}
+ \end{column}
+ \end{columns}
+
+\end{frame}
+
+\begin{frame}[fragile,label=current]{Copy vs move \insertcontinuationtext}
+
+ \begin{columns}
+ \begin{column}{.45\textwidth}
+
+ \begin{codeblock}{\tiny
+\uncover<1->{class String \{
+ char* s\_;
+ public:
+ String(char const* s) \{
+ size\_t size = strlen(s) + 1;
+ s\_ = new char[size];
+ memcpy(s\_, s, size);
+ \}
+ ~String() \{ delete [] s\_; \}}
+\uncover<2->{ // \alert<2>{copy}
+ String(String const& other) \{
+ size\_t size = strlen(other.s\_) + 1;
+ s\_ = new char[size];
+ memcpy(s\_, other.s\_, size);
+ \}}
+\uncover<4->{ // \alert<4-5>{move}
+ String(\alert<7>{???} tmp): s\_(tmp.s\_) \{
+\uncover<5->{ tmp.s\_ = nullptr;}
+ \}}
+\uncover<1->{ \ldots
+\};
+
+String s1\{"Hi!"\};}
+\uncover<2->{String s2\{s1\};}
+\uncover<3->{String \alert<4>{s3}\{\alert<3>{get\_string()}\}\alert<6>{;}}
+}\end{codeblock}
+
+ \end{column}
+
+ \begin{column}{.55\textwidth}
+ \newcommand*{\stackx}{0.}
+ \newcommand*{\heapx}{3.0}
+
+ \begin{tikzpicture}
+ [anchor=south west]
+ \node at (\stackx,0) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=7cm,
+ draw=black,
+ label={90:{\scriptsize stack}}
+ ] {};
+ \node at (\heapx,0) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=7cm,
+ draw=black,
+ label={90:{\scriptsize heap}}
+ ] {};
+ \node at (\heapx-0.1,4.9) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=0.7cm,
+ ] {};
+ \node at (\heapx,5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white
+ ] {\scriptsize\tt Hi!\char`\\0};
+ \node at (\heapx,5) [
+ rectangle,
+ minimum width=.5cm,
+ minimum height=.5cm,
+ draw=black,
+ densely dotted,
+ label={270:{\scriptsize\tt 0x4abc}}
+ ] {};
+ \node at (\stackx-0.1,4.9) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=.7cm,
+ label={180:{\scriptsize\tt s1}},
+ ] {};
+ \node at (\stackx,5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white,
+ ] {\scriptsize\tt 0x4abc};
+ \visible<2->{
+ \node at (\heapx-0.1,3.9) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=0.7cm,
+ ] {};
+ \node at (\heapx,4) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white
+ ] {\scriptsize\tt Hi!\char`\\0};
+ \node at (\heapx,4) [
+ rectangle,
+ minimum width=.5cm,
+ minimum height=.5cm,
+ draw=black,
+ densely dotted,
+ label={270:{\scriptsize\tt 0x4ab0}}
+ ] (r2) {};
+ \node at (\stackx-0.1,3.9) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=.7cm,
+ label={180:{\scriptsize\tt s2}},
+ ] {};
+ \node at (\stackx,4) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white,
+ ] (h2) {\scriptsize\tt 0x4ab0};
+ %\draw[arrow] (h2) -- (r2);
+ }
+ \visible<4->{
+ \node at (\stackx-0.1,2.4) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=.7cm,
+ label={180:{\scriptsize\tt s3}},
+ ] {};
+ \node at (\stackx,2.5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white,
+ ] {\scriptsize\tt \alert<4>{0x4aa0}};
+ }
+ \visible<3->{
+ \node at (\heapx-0.1,1.4) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=0.7cm,
+ ] {};
+ \node at (\heapx,1.5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white
+ ] {\scriptsize\tt Hey\char`\\0};
+ \node at (\heapx,1.5) [
+ rectangle,
+ minimum width=.5cm,
+ minimum height=.5cm,
+ draw=black,
+ densely dotted,
+ label={270:{\scriptsize\tt 0x4aa0}}
+ ] {};
+ }
+ \visible<3-5>{
+ \node at (\stackx-0.1,1.4) [
+ rectangle,
+ fill=green!10!white,
+ draw=black!40,
+ minimum width=2.2cm,
+ minimum height=.7cm,
+ ] {};
+ \node at (\stackx,1.5) [
+ rectangle,
+ minimum width=2cm,
+ minimum height=.5cm,
+ draw=black,
+ fill=green!30!white,
+ ] {\scriptsize\tt \alt<3-4>{\alert<4>{0x4aa0}}{\code{\alert<5>{nullptr}}}};
+ }
+ \end{tikzpicture}
+ \end{column}
+ \end{columns}
+\end{frame}
+
+\begin{frame}[label=current]{lvalues vs rvalues}
+ \begin{itemize}
+ \item The taxonomy of values in C++ is complex
+ \begin{itemize}
+ \item glvalue, prvalue, xvalue, lvalue, rvalue
+ \end{itemize}
+ \item We can assume
+ \begin{description}
+ \item [lvalue] A named object
+ \begin{itemize}
+ \item for which you can take the address
+ \item \alert{l} stands for ``left'' because it used to represent the
+ \alert{l}eft-hand side of an assignment
+ \end{itemize}
+ \item [rvalue] An unnamed (temporary) object
+ \begin{itemize}
+ \item for which you can't take the address
+ \item \alert{r} stands for ``right'' because it used to represent the
+ \alert{r}ight-hand side of an assignment
+ \end{itemize}
+ \end{description}
+ \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile,label=current]{Rvalue reference}
+ \begin{itemize}
+ \item A \texttt{T\&\&} is an rvalue reference
+ \begin{itemize}
+ \item introduced in C++11
+ \end{itemize}
+ \item It binds to rvalues but not to lvalues
+ \end{itemize}
+
+ \begin{codeblock}<2->{\tiny
+class Thing;
+Thing make\_thing();
+
+Thing t;
+
+\uncover<3->{Thing & r = t;}\uncover<4->{ // ok}
+\uncover<5->{Thing && r = t;}\uncover<6->{ // error}
+\uncover<7->{Thing & r = make\_thing();}\uncover<8->{ // error}
+\uncover<9->{Thing && r = make\_thing();}\uncover<10->{ // ok}
+\uncover<11->{Thing const& r = make\_thing();}\uncover<12->{ // ok (!)}
+\uncover<13->{Thing const&& r = make\_thing();}\uncover<14->{ // ok, but what for?}}\end{codeblock}
+
+ \begin{codeblock}<15->{\tiny
+class String \{
+ // move constructor
+ String(String\alert<15>{&&} tmp) : s\_(tmp.s\_) \{
+ tmp.s\_ = nullptr;
+ \}
+\};
+
+String s2\{s1\}; // call String::String(String const&)
+String s3\{get\_string()\}; // call String::String(String&&)}\end{codeblock}
+
+\end{frame}
+
+\begin{frame}[fragile,label=current]{Rvalue reference \insertcontinuationtext}
+ \begin{itemize}
+ \item Any function can accept rvalue references
+ \begin{codeblock}
+void foo(String&&);
+
+foo(get\_string());
+foo(String\{"hello"\});\end{codeblock}
+ \item lvalues can be explicitly transformed into rvalues
+ \begin{codeblock}
+String s;
+foo(s); // error
+foo(std::move(s)); // ok, I don't care any more about s
+s.size(); // dangerous\end{codeblock}
+ \end{itemize}
+\end{frame}
+
+
\begin{frame}[fragile]{Smart pointers \insertcontinuationtext}
\begin{columns}[c]
@@ -2099,241 +2606,6 @@ Handle h1\{10\}, h2\{20\};
arrow/.style={->}
}
-\begin{frame}[fragile]{Copy vs move}
-
- \begin{columns}
- \begin{column}{.45\textwidth}
-
- \begin{codeblock}<1->
-Handle h1\{123\};
-\uncover<2->{Handle h2\{h1\};}\end{codeblock}
-
- \uncover<3->{\small
- \begin{itemize}
- \item Both \texttt{h1} and \texttt{h2} exist at the end
- \item The ``deep'' copy is needed
- \end{itemize}
- }
-
- \begin{codeblock}<4->
-Handle make\_holder();
-Handle \alert<6>{h3}\{\alert<5>{make\_holder()}\}\alert<7>{;}\end{codeblock}
-
- \uncover<8->{\small
- \begin{itemize}
- \item Only \texttt{h3} exists at the end
- \item The ``deep'' copy is a waste
- \item Could reuse the ``guts'' of the temporary
- \end{itemize}
- }
- \end{column}
-
- \begin{column}{.55\textwidth}
- \newcommand*{\stackx}{0.}
- \newcommand*{\heapx}{3.0}
-
- \begin{tikzpicture}
- [anchor=south west]
- \node at (\stackx,0) [
- rectangle,
- minimum width=2cm,
- minimum height=7cm,
- draw=black,
- label={90:{\scriptsize stack}}
- ] {};
- \node at (\heapx,0) [
- rectangle,
- minimum width=2cm,
- minimum height=7cm,
- draw=black,
- label={90:{\scriptsize heap}}
- ] {};
- \node at (\heapx-0.1,4.9) [
- rectangle,
- fill=green!10!white,
- draw=black!40,
- minimum width=2.2cm,
- minimum height=0.7cm,
- ] {};
- \node at (\heapx,5) [
- rectangle,
- minimum width=2cm,
- minimum height=.5cm,
- draw=black,
- fill=green!30!white
- ] {\scriptsize\tt 123};
- \node at (\heapx,5) [
- rectangle,
- minimum width=.5cm,
- minimum height=.5cm,
- draw=black,
- densely dotted,
- label={270:{\scriptsize\tt 0x4abc}}
- ] {};
- \node at (\stackx-0.1,4.9) [
- rectangle,
- fill=green!10!white,
- draw=black!40,
- minimum width=2.2cm,
- minimum height=.7cm,
- label={180:{\scriptsize\tt h1}},
- ] {};
- \node at (\stackx,5) [
- rectangle,
- minimum width=2cm,
- minimum height=.5cm,
- draw=black,
- fill=green!30!white,
- ] {\scriptsize\tt 0x4abc};
- \visible<2->{
- \node at (\heapx-0.1,3.9) [
- rectangle,
- fill=green!10!white,
- draw=black!40,
- minimum width=2.2cm,
- minimum height=0.7cm,
- ] {};
- \node at (\heapx,4) [
- rectangle,
- minimum width=2cm,
- minimum height=.5cm,
- draw=black,
- fill=green!30!white
- ] {\scriptsize\tt 123};
- \node at (\heapx,4) [
- rectangle,
- minimum width=.5cm,
- minimum height=.5cm,
- draw=black,
- densely dotted,
- label={270:{\scriptsize\tt 0x4ab0}}
- ] (r2) {};
- \node at (\stackx-0.1,3.9) [
- rectangle,
- fill=green!10!white,
- draw=black!40,
- minimum width=2.2cm,
- minimum height=.7cm,
- label={180:{\scriptsize\tt h2}},
- ] {};
- \node at (\stackx,4) [
- rectangle,
- minimum width=2cm,
- minimum height=.5cm,
- draw=black,
- fill=green!30!white,
- ] (h2) {\scriptsize\tt 0x4ab0};
- %\draw[arrow] (h2) -- (r2);
- }
- \visible<6->{
- \node at (\heapx-0.1,2.4) [
- rectangle,
- fill=green!10!white,
- draw=black!40,
- minimum width=2.2cm,
- minimum height=0.7cm,
- ] {};
- \node at (\heapx,2.5) [
- rectangle,
- minimum width=2cm,
- minimum height=.5cm,
- draw=black,
- fill=green!30!white
- ] {\scriptsize\tt 456};
- \node at (\heapx,2.5) [
- rectangle,
- minimum width=.5cm,
- minimum height=.5cm,
- draw=black,
- densely dotted,
- label={270:{\scriptsize\tt 0x4aac}}
- ] {};
- \node at (\stackx-0.1,2.4) [
- rectangle,
- fill=green!10!white,
- draw=black!40,
- minimum width=2.2cm,
- minimum height=.7cm,
- label={180:{\scriptsize\tt h3}},
- ] {};
- \node at (\stackx,2.5) [
- rectangle,
- minimum width=2cm,
- minimum height=.5cm,
- draw=black,
- fill=green!30!white,
- ] {\scriptsize\tt 0x4aac};
- }
- \visible<5-6>{
- \node at (\heapx-0.1,1.4) [
- rectangle,
- fill=green!10!white,
- draw=black!40,
- minimum width=2.2cm,
- minimum height=0.7cm,
- ] {};
- \node at (\heapx,1.5) [
- rectangle,
- minimum width=2cm,
- minimum height=.5cm,
- draw=black,
- fill=green!30!white
- ] {\scriptsize\tt 456};
- \node at (\heapx,1.5) [
- rectangle,
- minimum width=.5cm,
- minimum height=.5cm,
- draw=black,
- densely dotted,
- label={270:{\scriptsize\tt 0x4aa0}}
- ] {};
- \node at (\stackx-0.1,1.4) [
- rectangle,
- fill=green!10!white,
- draw=black!40,
- minimum width=2.2cm,
- minimum height=.7cm,
- ] {};
- \node at (\stackx,1.5) [
- rectangle,
- minimum width=2cm,
- minimum height=.5cm,
- draw=black,
- fill=green!30!white,
- ] {\scriptsize\tt 0x4aa0};
- }
- \end{tikzpicture}
- \end{column}
- \end{columns}
-
-\end{frame}
-
-\section{Move semantics}
-
-\begin{frame}{lvalues vs rvalues}
- \begin{itemize}
- \item The taxonomy of values in C++ is complex
- \begin{itemize}
- \item glvalue, prvalue, xvalue, lvalue, rvalue
- \end{itemize}
- \item We can assume
- \begin{description}
- \item [lvalue] A named object
- \begin{itemize}
- \item for which you can take the address
- \item \alert{l} stands for ``left'' because it used to represent the
- \alert{l}eft-hand side of an assignment
- \end{itemize}
- \item [rvalue] An unnamed (temporary) object
- \begin{itemize}
- \item for which you can't take the address
- \item \alert{r} stands for ``right'' because it used to represent the
- \alert{r}ight-hand side of an assignment
- \end{itemize}
- \end{description}
- \end{itemize}
-\end{frame}
-
\begin{frame}[fragile]{Move constructor}
\begin{columns}
@@ -2447,33 +2719,6 @@ Handle \alert<3-5>{h\{}\alert<2>{make\_holder()}\alert<3-5>{\}}\alert<6>{;}\end{
\end{frame}
-\begin{frame}[fragile]{Rvalue reference}
- \begin{itemize}
- \item A \texttt{T\&\&} is an rvalue reference
- \item It binds to rvalues but not to lvalues
- \end{itemize}
-
- \begin{codeblock}<2->{
-class Thing;
-Thing make\_thing();
-
-Thing t;
-
-\uncover<3->{Thing & r = t;}\uncover<4->{ // ok}
-\uncover<5->{Thing && r = t;}\uncover<6->{ // error}
-\uncover<7->{Thing & r = make\_thing();}\uncover<8->{ // error}
-\uncover<9->{Thing && r = make\_thing();}\uncover<10->{ // ok}
-\uncover<11->{Thing const& r = make\_thing();}\uncover<12->{ // ok (!)}
-\uncover<13->{Thing const&& r = make\_thing();}\uncover<14->{ // ok, but what for?}}\end{codeblock}
-
- \uncover<15->{
- \begin{itemize}
- \item A reference extends the lifetime of a temporary object until the end of the scope
- \end{itemize}
- }
-
-\end{frame}
-
\begin{frame}[fragile]{Move assignment}
\begin{columns}
--
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