אביב תשס"ה jctתיכון תוכנה: ד"ר ראובן גלנט1 פרק 8...

1תיכון תוכנה: ד"ר ראובן גלנטJCT אביב תשס"ה

8פרק 7-9נקודות חשובות בתרגילים


1. Initializer


Inheritance• Make the PressureSensor and TemperatureSensor

inherit from the base class Sensor.• Add directed associations from the Motor to the

PressureSensor and to the TemperatureSensor.• Set the multiplicity to 1.


Base Class Sensor• Add attribute name of type OMString• Add a constructor that receives an argument

aName of type OMString • Initialize the attribute in the initializer name(aName)• Create an operation print with implementation

std::cout << name << “ “;


Base Class Sensor-Sensor.cpp

//file Sensor.cpp#include “Sensor.h”

Sensor::Sensor(OMString aName): name(aName) { }

void Sensor::print() {std::cout << name << “ “;}


Motor Class• Create a constructor that creates instances of

both types of Sensor:• setItsTemperatureSensor(new TemperatureSensor(“T1”));• setItsPressureSensor(new PressureSensor(“P1”));


Class Motor- Motor.cpp

//file Motor.cpp#include “Motor.cpp#include “Sensor.h” Motor::Motor() { setItsTemperatureSensor(new TemperatureSensor(“T1”)); setItsPressureSensor(new PressureSensor(“P1”));}


Derived Sensor Classes• For both derived Sensor classes:• Create a constructor that has an argument

aName of type OMString• Set the Initializer to Sensor(aName)

Sensor(aName) invokes the Sensor constructor so as to initialize the name field of the base class.


Derived Classes: TemperatureSensor.cpp

//file TemperatureSensor.cpp

#include “TemperatureSensor.h”

TemperatureSensor::TemperatureSensor(OMString aName): Sensor(aName) { }


Animating• Create a Test component and a Debug configuration

that creates an initial instance of the Motor class• Save / Generate / Make / Run • With the browser, note that there are two instances of

Sensor. Each Sensor has a name that has been initialized.


User Types• Using the browser, right-click on the Default

package and select “Add New Type” • add a type tTempUnits declared as

– enum tTempUnits { CELSIUS, FAHRENHEIT };

An alternative declaration is :enum %s { CELSIUS, FAHRENHEIT }.


Attribute Unit• Add an attribute unit of type tTempUnits for the

TemperatureSensor.• Add an argument to the TemperatureSensor

constructor called aUnit of the same type • In the initializer add ,unit(aUnit)


TemperatureSensor• Change the read operation to :

std::cout << “Temperature = “ << rand() % 100 << “deg “;

if ( unit == CELSIUS )

std::cout << “C” << std::endl;

else

std::cout << “F” << std::endl;

• In the Motor constructor, add the argument “CELSIUS” as follows:

setItsTemperatureSensor (new TemperatureSensor( “T1”, CELSIUS));


2. Container Classes (OMCollection)

andIterators

(OMIterator)


Using OMIterator• Rhapsody provides an OMIterator class that

can be used as follows to iterate through a container:

OMCollection<Sensor*> itsSensor; // a container

OMIterator<Sensor*> iSensor(itsSensor);iSensor.reset(); // point to firstwhile ( *iSensor != NULL ) { (*iSensor)->print(); // print ++iSensor; // point to next}


Collection of Sensors• Load the “Virtual” project and save as “Collection”• Delete from Model the relations between the Motor and

the Sensors. Check in the Browser that these relations have been deleted from the model not just the view.

• Add a directed aggregation itsSensor from the Motor to the Sensor. Set Multiplicity to * (many).


OMCollection• Delete implementation of Motor constructor• Save / Generate / Examine code for Motor• Note that the relation has been implemented as a collection of

Sensors:

OMCollection<Sensor*> itsSensor;• Note also that there is an operation

addItsSensor(Sensor* p_Sensor);


OMCollection: Motor.h#ifndef Motor_H #define Motor_H #include "PressureSensor.h"#include "TemperatureSensor.h"class Sensor;public : //defined by user void addSensor(); void deleteSensor(); void pollSensors();

public: //defined by Rhapsody OMIterator<Sensor*> getItsSensor() const; void addItsSensor(Sensor* p_Sensor); void removeItsSensor(Sensor* p_Sensor); void clearItsSensor();

protected : OMCollection<Sensor*> itsSensor;};#endif


Adding to OMCollection• In the motor constructor add Sensors:

– addItsSensor(new TemperatureSensor(“Sensor1”,CELSIUS));

– addItsSensor(new TemperatureSensor(“Sensor2”,FAHRENHEIT));

– addItsSensor(new PressureSensor(“Sensor3”) );


2.a Dependencies


Dependencies• In order to compile, the Motor needs to include

the Pressure and Temperature Sensors header files. To do this we will add dependencies from the Motor to those classes:

• Double-click on each dependency and select the stereotype Usage.


Implementation Includes• Alternatively instead of drawing dependencies,

we can just modify the properties for the Motor class and for CPP_CG->Class->ImpIncludes add TemperatureSensor.h,PressureSensor.h

CPP_CG means C++ Code Generation.


Multiple Relation• Save / Generate / Make / Run• Show that the Motor has a collection of three

Sensors.


Statechart• Create a simple Statechart for the Motor class

that calls a pollSensors() routine every two seconds.


pollSensors()• Create the pollSensors() operation that will

poll all the Sensors in the collection:

Note that if any more Sensors of any other type are added, the operation still functions!

OMIterator<Sensor*> iSensor(itsSensor);for ( iSensor.reset(); *iSensor; ++iSensor ) { (*iSensor)->print(); (*iSensor)->read();} cout << "---------------------" << endl;


Extended Exercise• For the Sensor class, add a static attribute

numberOfSensors of type int with initial value 0.

• In the Sensor Constructor add numberOfSensors++;

• For the Sensor class, add a virtual Destructor with implementation : numberOfSensors--;

• Add the following to pollSensors() cout << “Number of sensors = “ << Sensor::getNumberOfSensors() << endl;

• Generate code and execute to check that numberOfSensors = 3.


3. Threads, Active Classes, Statechart Inheritance


Concurrency• We want each Sensor to run on its own thread

(active class). • To do so, we need each Sensor to be

Reactive (class that waits for events). • So we will create a Statechart for the base

Sensor class as follows:


Active Classes• With the browser, change the concurrency of

the Sensor class from sequential to active.


Inheriting Behavior• Open the Statecharts for the PressureSensor

and TemperatureSensor. Note that they have inherited the base class Statechart.

• Specialize the behavior of the TemperatureSensor as below:

Grayed out indicatinginherited behavior


Starting the Behavior• Add a call to startBehavior() from the

TemperatureSensor and PressureSensor constructors to initialize the statecharts.

If we had used a composite class, Rhapsody would have done this for us, but that would have been too easy !


Multi-threads• Save / Generate / Make / Run• Check that there are four active threads.• Setting the focus to a particular thread displays

the call stack and event queue for that thread.

There will always be one thread called mainThread.


Suspending Threads• Note that a thread can be suspended.


Problems with the Design• With the current design there are a few

potential problems:– The Motor class needs to know about all

the different types of Sensor.– If another class wants access to the

Sensors, it too will need to depend upon all the different types of Sensor.

– Starting the behavior of a Sensor, in the constructor is not very elegant.

– Adding a new type of Sensor means finding and modifying all classes that use Sensor.


4. Singleton, Abstract Factory


Improving the Design• Using the “factory method design pattern” will

solve all these concerns.• A SensorFactory class can be introduced that is

used by all classes ( ex: Motor ) that need to get a Sensor. This decouples the Motor class from the actual Sensors and can also start the behavior of the Sensors.

• The SensorFactory will be implemented using the “Singleton design pattern” (to ensure that there is only one instance of SensorFactory).

See the “SensorFactory” example.


The Improved Design


The Singleton Design Pattern I

Protectedconstructor

Static attribute


The Singleton Design Pattern II

Static factoryoperation

Calling thecreateRandomSensor

operation


SensorFactory::createRandomSensor()Sensor * SensorFactory::createRandomSensor(){ Sensor* aSensor; OMString aName; char index[10];

//itoa(Sensor::getCount(), index, 10); strcpy ( index, "1" ); aName = "Sensor" + OMString(index);

switch ( rand() % 4 ) { default: case 0: aSensor = new TemperatureSensor( aName, CELSIUS ); break; case 1: aSensor= new TemperatureSensor( aName, FAHRENHEIT ); break; case 2: aSensor = new PressureSensor( aName ); break; case 3: aSensor = new SpeedSensor( aName ); break; } aSensor->startBehavior(); return aSensor;}

אביב תשס"ה jctתיכון תוכנה: ד"ר ראובן גלנט1 פרק 8...

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