Doc: Replace std::bind() with lambdas in Qt Concurrent

Lambda functions provide all the benefits of std::bind() plus more

Change-Id: Iec30b20bb35ac0fae560435b323f80af2f2e5fce
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

src/concurrent/doc/snippets/code/src_concurrent_qtconcurrentfilter.cpp

@@ -145,19 +145,11 @@ bool QString::contains(const QRegularExpression &regexp) const;
 //! [9]
 
 
-//! [10]
-std::bind(&QString::contains, QRegularExpression("^\\S+$")); // matches strings without whitespace
-//! [10]
-
-
-//! [11]
-bool contains(const QString &string)
-//! [11]
-
-
 //! [12]
 QStringList strings = ...;
-std::bind(static_cast<bool(QString::*)(const QRegularExpression&)>( &QString::contains ), QRegularExpression("..."));
+QFuture<QString> future = QtConcurrent::filtered(list, [](const QString &str) {
+    return str.contains(QRegularExpression("^\\S+$")); // matches strings without whitespace
+});
 //! [12]
 
 //! [13]

src/concurrent/doc/snippets/code/src_concurrent_qtconcurrentmap.cpp

@@ -158,19 +158,11 @@ QImage QImage::scaledToWidth(int width, Qt::TransformationMode) const;
 //! [10]
 
 
-//! [11]
-std::bind(&QImage::scaledToWidth, 100, Qt::SmoothTransformation)
-//! [11]
-
-
-//! [12]
-QImage scaledToWith(const QImage &image)
-//! [12]
-
-
 //! [13]
 QList<QImage> images = ...;
-QFuture<QImage> thumbnails = QtConcurrent::mapped(images, std::bind(&QImage::scaledToWidth, 100, Qt::SmoothTransformation));
+QFuture<QImage> thumbnails = QtConcurrent::mapped(images, [](const QImage &img) {
+    return img.scaledToWidth(100, Qt::SmoothTransformation);
+});
 //! [13]
 
 //! [14]

src/concurrent/doc/snippets/code/src_concurrent_qtconcurrentrun.cpp

@@ -109,7 +109,8 @@ future.waitForFinished();
 
 
 //! [6]
-void someFunction(int arg1, double arg2);
-QFuture<void> future = QtConcurrent::run(std::bind(someFunction, 1, 2.0));
+QFuture<void> future = QtConcurrent::run([=]() {
+    // Code in this block will run in another thread
+});
 ...
 //! [6]

src/concurrent/qtconcurrentfilter.cpp

@@ -148,13 +148,11 @@
 
     \snippet code/src_concurrent_qtconcurrentfilter.cpp 13
 
-    \section2 Using Bound Function Arguments
+    \section2 Wrapping Functions that Take Multiple Arguments
 
     If you want to use a filter function takes more than one argument, you can
-    use std::bind() to transform it onto a function that takes one argument. If
-    C++11 support is not available, \l{http://www.boost.org/libs/bind/bind.html}
-    {boost::bind()} or \l{http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf}
-    {std::tr1::bind()} are suitable replacements.
+    use a lambda function or \c std::bind() to transform it onto a function that
+    takes one argument.
 
     As an example, we use QString::contains():
 
@@ -166,16 +164,6 @@
     use QString::contains() with QtConcurrent::filtered() we have to provide a
     value for the \e regexp argument:
 
-    \snippet code/src_concurrent_qtconcurrentfilter.cpp 10
-
-    The return value from std::bind() is a function object (functor) with
-    the following signature:
-
-    \snippet code/src_concurrent_qtconcurrentfilter.cpp 11
-
-    This matches what QtConcurrent::filtered() expects, and the complete
-    example becomes:
-
     \snippet code/src_concurrent_qtconcurrentfilter.cpp 12
 */
 

src/concurrent/qtconcurrentmap.cpp

@@ -198,13 +198,11 @@
 
     \snippet code/src_concurrent_qtconcurrentmap.cpp 14
 
-    \section2 Using Bound Function Arguments
+    \section2 Wrapping Functions that Take Multiple Arguments
 
     If you want to use a map function that takes more than one argument you can
-    use std::bind() to transform it onto a function that takes one argument. If
-    C++11 support is not available, \l{http://www.boost.org/libs/bind/bind.html}
-    {boost::bind()} or \l{http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf}
-    {std::tr1::bind()} are suitable replacements.
+    use a lambda function or \c std::bind() to transform it onto a function that
+    takes one argument.
 
     As an example, we'll use QImage::scaledToWidth():
 
@@ -216,16 +214,6 @@
     QImage::scaledToWidth() with QtConcurrent::mapped() we have to provide a
     value for the \e{width} and the \e{transformation mode}:
 
-    \snippet code/src_concurrent_qtconcurrentmap.cpp 11
-
-    The return value from std::bind() is a function object (functor) with
-    the following signature:
-
-    \snippet code/src_concurrent_qtconcurrentmap.cpp 12
-
-    This matches what QtConcurrent::mapped() expects, and the complete example
-    becomes:
-
     \snippet code/src_concurrent_qtconcurrentmap.cpp 13
 */
 

src/concurrent/qtconcurrentrun.cpp

@@ -107,25 +107,9 @@
 
     \snippet code/src_concurrent_qtconcurrentrun.cpp 5
 
-    \section2 Using Bound Function Arguments
+    \section2 Using Lambda Functions
 
-    You can use std::bind() to \e bind a number of arguments to a function when
-    called. If C++11 support is not available, \l{http://www.boost.org/libs/bind/bind.html}
-    {boost::bind()} or \l{http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf}
-    {std::tr1::bind()} are suitable replacements.
-
-    There are number of reasons for binding:
-
-    \list
-    \li To call a function that takes more than 5 arguments.
-    \li To simplify calling a function with constant arguments.
-    \li Changing the order of arguments.
-    \endlist
-
-    See the documentation for the relevant functions for details on how to use
-    the bind API.
-
-    Calling a bound function is done like this:
+    Calling a lambda function is done like this:
 
     \snippet code/src_concurrent_qtconcurrentrun.cpp 6
 */