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--- getting_started:cplusplus [2015/10/14 14:22] – [Templates] graf
+++ getting_started:cplusplus [2017/09/24 15:29] (current) – removed graf
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-====== C++ for Beginners ======
-This is a very short introduction into a couple of concepts of C++. It should enable a beginner without knowledge in C++ to properly use EEROS in an own simple application.
-===== Namespaces =====
-With namespaces you can group entities such as classes or enums under a choosen name. In this way the global scope can be split into subscopes with distinguished names. EEROS heavely uses namespaces.  \\
-In order to use declarations from these namespaces we can either import such a namespace or use the scope operator '::'. Let's look at an example.
-<code cpp>
-using namespace eeros::logger;
-int main(int argc, char **argv) {
-  StreamLogWriter w(std::cout);
-  Logger<LogWriter>::setDefaultWriter(&w);
-  Logger<LogWriter> log;
-  eeros::control::Constant<std::array<double,4>> c1;
-  using eeros::control::Gain;
-  Gain<> g1;
-</code>
-With 'using namespace eeros::logger' all the declarations in this namespace are made visible and can be directly used. \\
-The block 'Const' within the namespace 'eeros::control' is used with the aid of the scope operator.\\
-The block 'Gain' within the namespace 'eeros::control' is made available by 'using eeros::control::Gain;' and can be referred to further on without qualifying with the namespace.
-===== Using Constructors =====
-Constructors - as any other function - can be overloaded. Many blocks you may want to use in your control system can be instantiated in various ways. Let us consider an example with a ''Gain'' block.
-<code cpp>
-using namespace eeros::control;
-int main(int argc, char **argv) {
-	Gain<> g1(10);
-	Gain<> g2;
-	g2.setGain(10);
-}
-</code>
-The first constructor initializes a gain block and sets its gain value to 10. The second instance of the same block is created with a gain value defaulting to 1. This value could then be subsequently set to 10.
-===== Templates =====
-Function and class templates are widely used within the eeros framework. Templates allow the parametrization of many blocks and signals. This should be demonstrated with the example of a ''Constant'' block. Such a block should be able to contain a single constant value of any type. It should also be able to hold a multidimensional value.
-<code cpp>
-using namespace eeros::control;
-using namespace eeros::math;
-int main(int argc, char **argv) {
-  Constant<> c1(2.5);  // type double
-  Constant<int16_t> c2(10);  // type int16_t
-  Constant<Matrix<2,1>> c3({2,1.5});  // type Matrix
-  c1.run();
-  log.info() << c1.getOut().getSignal().getValue();
-</code>
-The square brackets - even if left empty - are necessary, because a ''Constant'' block requires a signal type for its output. The block is instantiated per default with a value of type ''double''. The second declaration chooses a different type. The third declaration uses a type different from an arithmetic type. The type ''Matrix'' is a built-in type which itself can be parametrized with its dimensions. \\
-Do not forget to call the method ''run''. Without this value of the block is not written to its output signal.