// Purpose. Facade #include <iostream.h>
// #include <string.h>
// Discussion. Class Compute models #define sl strlen
// a decimal digit adder module. An
// entire "subsystem" can be configur- class Compute {
// ed by linking as many of these public:
// modules as the desired precision char add( char a, char b, int& c ) {
// requires. The "subsystem" being int result = a + b + c - 96;
// modeled in main() is complex and c = 0;
// burdensome to use. Wrapping this if (result > 9) {
// subsystem inside of a Facade that result -= 10;
// exports a simple interface is c = 1;
// desirable. }
return result + 48;
#include <iostream.h> }
#include <string.h> };
#define sl strlen
class Facade {
class Compute { public:
public: char* add( char* a, char* b ) {
char add( char a, char b, int& c) { int cary = 0, i = 0;
int result = a + b + c - 96; char c, d;
c = 0; if ((sl(a) > 1) && (sl(b) > 1)) {
if (result > 9) { c = ones.add( a[1], b[1], cary );
result -= 10; d = tens.add( a[0], b[0], cary );
c = 1; } else if (sl(a) > 1) {
} c = ones.add( a[1], b[0], cary );
return result + 48; d = tens.add( a[0], '0', cary );
} } else if (sl(b) > 1) {
}; c = ones.add( b[1], a[0], cary );
d = tens.add( b[0], '0', cary );
void main( void ) { } else {
Compute tens, ones; c = tens.add( a[0], b[0], cary );
char a[9], b[9], c, d; d = 'x';
int cary; }
while (1) { if (cary) ans[i++] = '1';
cout << "Enter 2 nums: "; if (d != 'x') ans[i++] = d;
cin >> a >> b; ans[i++] = c;
cout << " sum is "; ans[i] = '\0';
cary = 0; return ans;
if ((sl(a) > 1) && (sl(b) > 1)) { }
c = ones.add( a[1], b[1], cary); private:
d = tens.add( a[0], b[0], cary); Compute tens, ones;
} else if (sl(a) > 1) { char ans[9];
c = ones.add( a[1], b[0], cary); };
d = tens.add( a[0], '0', cary);
} else if (sl(b) > 1) { void main( void ) {
c = ones.add( b[1], a[0], cary); Facade f;
d = tens.add( b[0], '0', cary); char a[9], b[9];
} else { while (1) {
c = tens.add( a[0], b[0], cary); cout << "Enter 2 nums: ";
d = 'x'; cin >> a >> b;
} cout <<" sum is "<< f.add(a,b)
if (cary) cout << '1'; << endl;
if (d != 'x') cout << d; } }
cout << c << endl;
} } // Enter 2 nums: 9 13
// sum is 22
// Enter 2 nums: 99 99 // Enter 2 nums: 19 8
// sum is 198 // sum is 27
// Enter 2 nums: 38 83 // Enter 2 nums: 3 99
// sum is 121 // sum is 102
// Enter 2 nums: 5 6
// sum is 11



// Purpose. Facade design pattern demo.
//
// Discussion. Structuring a system into subsystems helps reduce
// complexity. A common design goal is to minimize the communication and
// dependencies between subsystems. One way to achieve this goal is to
// introduce a "facade" object that provides a single, simplified
// interface to the many, potentially complex, individual interfaces
// within the subsystem. In this example, the "subsystem" for responding
// to a networking service request has been modeled, and a facade
// (FacilitiesFacade) interposed. The facade "hides" the twisted and
// bizarre choreography necessary to satisfy even the most basic of
// requests. All the user of the facade object has to do is make one or
// two phone calls a week for 5 months, and a completed service request
// results.

#include <iostream.h>

class MisDepartment {
public:
void submitNetworkRequest() { _state = 0; }
bool checkOnStatus() {
_state++;
if (_state == Complete)
return 1;
return 0; }
private:
enum States {Received, DenyAllKnowledge, ReferClientToFacilities,
FacilitiesHasNotSentPaperwork, ElectricianIsNotDone,
ElectricianDidItWrong, DispatchTechnician, SignedOff, DoesNotWork,
FixElectriciansWiring, Complete};
int _state;
};

class ElectricianUnion {
public:
void submitNetworkRequest() { _state = 0; }
bool checkOnStatus() {
_state++;
if (_state == Complete)
return 1;
return 0; }
private:
enum States {Received, RejectTheForm, SizeTheJob, SmokeAndJokeBreak,
WaitForAuthorization, DoTheWrongJob, BlameTheEngineer, WaitToPunchOut,
DoHalfAJob, ComplainToEngineer, GetClarification, CompleteTheJob,
TurnInThePaperwork, Complete};
int _state;
};

class FacilitiesDepartment {
public:
void submitNetworkRequest() { _state = 0; }
bool checkOnStatus() {
_state++;
if (_state == Complete)
return 1;
return 0; }
private:
enum States {Received, AssignToEngineer, EngineerResearches,
RequestIsNotPossible, EngineerLeavesCompany, AssignToNewEngineer,
NewEngineerResearches, ReassignEngineer, EngineerReturns,
EngineerResearchesAgain, EngineerFillsOutPaperWork, Complete};
int _state;
};

class FacilitiesFacade {
public:
FacilitiesFacade() { _count = 0; }
void submitNetworkRequest() { _state = 0; }
bool checkOnStatus() {
_count++;
/* Job request has just been received */
if (_state == Received) {
_state++;
/* Forward the job request to the engineer */
_engineer.submitNetworkRequest();
cout << "submitted to Facilities - " << _count
<< " phone calls so far" << endl; }
else if (_state == SubmitToEngineer) {
/* If engineer is complete, forward to electrician */
if (_engineer.checkOnStatus()) {
_state++;
_electrician.submitNetworkRequest();
cout << "submitted to Electrician - " << _count
<< " phone calls so far" << endl; } }
else if (_state == SubmitToElectrician) {
/* If electrician is complete, forward to technician */
if (_electrician.checkOnStatus()) {
_state++;
_technician.submitNetworkRequest();
cout << "submitted to MIS - " << _count
<< " phone calls so far" << endl; } }
else if (_state == SubmitToTechnician) {
/* If technician is complete, job is done */
if (_technician.checkOnStatus())
return 1; }
/* The job is not entirely complete */
return 0; }
int getNumberOfCalls() { return _count; }
private:
enum States {Received, SubmitToEngineer, SubmitToElectrician,
SubmitToTechnician};
int _state;
int _count;
FacilitiesDepartment _engineer;
ElectricianUnion _electrician;
MisDepartment _technician;
};

void main() {
FacilitiesFacade facilities;

facilities.submitNetworkRequest();
/* Keep checking until job is complete */
while ( ! facilities.checkOnStatus())
;
cout << "job completed after only " << facilities.getNumberOfCalls()
<< " phone calls" << endl;
}

// submitted to Facilities - 1 phone calls so far
// submitted to Electrician - 12 phone calls so far
// submitted to MIS - 25 phone calls so far
// job completed after only 35 phone calls