code. compile. run. debug. share.
#include "Clock.h"
extern void appl(IClock&);
int main()
{
std::cout.setf(std::ios::boolalpha);
Clock c{};
appl(c);
}
#include <iostream>
#define SHOW(...)\
(void)(std::cout << __FILE__ << ':' << __LINE__ << '\t'\
<< #__VA_ARGS__ << " --> " << (__VA_ARGS__)\
<< std::endl)
#include "IClock.h"
void appl(IClock& c) {
SHOW(c);
c.TickUp(); SHOW(c);
c.TickUp(); SHOW(c);
c.TickUp(); SHOW(c);
c.Set(0, 0, 58); SHOW(c);
c.TickUp(); SHOW(c);
c.TickUp(); SHOW(c);
c.TickUp(); SHOW(c);
c.Set(0, 59, 58); SHOW(c);
c.TickUp(); SHOW(c);
c.TickUp(); SHOW(c);
c.TickUp(60); SHOW(c);
c.TickUp(600); SHOW(c);
}
#ifndef ICLOCK_H
#define ICLOCK_H
#include <iosfwd>
class IClock {
public:
virtual ~IClock() =default;
virtual void Set(int, int, int) =0;
virtual void TickUp(int = 1) =0;
virtual void Print(std::ostream&) const =0;
};
inline
std::ostream& operator<<(std::ostream& lhs, const IClock& rhs) {
rhs.Print(lhs);
return lhs;
}
#endif
#ifndef CLOCK_H
#define CLOCK_H
#include <iosfwd>
#include <cstring>
#include <iostream>
#include "IClock.h"
#include "LimitCounter.h"
#include "OverflowCounter.h"
class Clock : public IClock {
LimitCounter hours_;
OverflowCounter minutes_;
OverflowCounter seconds_;
public:
Clock(int hours = 0, int minutes = 0, int seconds = 0)
: hours_{24}
, minutes_{60, hours_}
, seconds_{60, minutes_}
{
Set(hours, minutes, seconds);
}
Clock(const Clock&) =delete; // copy c'tor
Clock& operator=(const Clock&) =delete; // copy assignment
Clock(Clock&&) =delete; // move c'tor
Clock& operator=(Clock&&) =delete; // move assignment
virtual void Set(int hours, int minutes, int seconds) override {
hours_.SetValue(hours);
minutes_.SetValue(minutes);
seconds_.SetValue(seconds);
}
virtual void TickUp(int seconds) override { seconds_.Count(seconds); }
virtual void Print(std::ostream&) const override;
};
#endif
#include "Clock.h"
#include <iostream>
#include <iomanip>
void Clock::Print(std::ostream& s) const {
std::ostream os{s.rdbuf()};
os.fill('0');
os << std::setw(2) << hours_.GetValue() << ':'
<< std::setw(2) << minutes_.GetValue() << ':'
<< std::setw(2) << seconds_.GetValue();
}
#ifndef ICOUNTER_H
#define ICOUNTER_H
class ICounter {
public:
virtual ~ICounter() =default;
virtual void Count() =0;
virtual void Reset() =0;
};
#endif
#ifndef COUNTER_H
#define COUNTER_H
#include "ICounter.h"
class LimitCounter : virtual public ICounter {
private:
int value_{};
const int max_value_{};
virtual void WillOverflow() {}
virtual void WillReset() {}
virtual void HasOverflowed() {}
virtual void HasResetted() {}
public:
LimitCounter() =delete;
LimitCounter(int max_value)
: value_{0}
, max_value_{max_value}
{}
void SetValue(int value) { value_ = value; }
int GetValue() const { return value_; }
void Count(int amount);
virtual void Count() override final;
virtual void Reset() override final;
};
#endif
#include "LimitCounter.h"
void LimitCounter::Count(int amount) {
while (amount-- > 0) {
Count();
}
}
void LimitCounter::Count() {
if (++value_ >= max_value_) {
WillOverflow();
value_ = 0;
HasOverflowed();
}
}
void LimitCounter::Reset() {
WillReset();
value_ = 0;
HasResetted();
}
#ifndef OVERFLOW_COUNTER_H
#define OVERFLOW_COUNTER_H
#include "ICounter.h"
#include "LimitCounter.h"
class OverflowCounter : virtual public ICounter
, private LimitCounter {
ICounter& next_counter_;
public:
OverflowCounter(int max_value, ICounter& next_counter)
: LimitCounter{max_value}
, next_counter_{next_counter}
{}
virtual void HasOverflowed() override;
virtual void HasResetted() override;
using LimitCounter::SetValue;
using LimitCounter::GetValue;
using LimitCounter::Count;
using LimitCounter::Reset;
};
#endif
#include "OverflowCounter.h"
void OverflowCounter::HasOverflowed() {
next_counter_.Count();
}
void OverflowCounter::HasResetted() {
next_counter_.Reset();
}
clock-5x:
g++ -std=c++14 *.cpp -o $@
run: clock-5x
./clock-5x
clean:
-rm -f *.o a.out core clock-5x
zip:
zip ../clock-5x.zip *.txt *.cpp *.h
Adding an Interface `ICounter`
------------------------------
+----------------+
| <<interface>> |
| ICounter |
| |
+-----.----.-----+
/_\ /_\
| |_____________________
| |
+----------------+ +-----------------+
| <<class>> | | <<class>> |
| LimitCounter |---<> OverflowCounter |
| | | |
+----------------+ +-----------------+
The imnterface ICounter` is implemented by `LimitCounter`, which
subsequently defines the extension points and is USED AS PART of
`OverflowCounter` (= Composition), which fills the extension
points to implement the added behavior.
Furthermore `OverflowCounter` would also need to IMPLEMENT the
interface `ICounter`, as member functions from used parts can
only be delegated to.
A speciality from C++ are "private base classes", essentially
composition too, but providing a short-hand for delegation via
`using` directives, which can be used to change visibility of
privately inherited member functions.
A minor pitfall here is that delegating via `using` directives to
the implementation of `ICounter` as done in `LimitCounter`,
COMING FROM `OverflowCounter`, technically is ambiguous. To avoid
the ambiguity it is necessary to make `ICounter` a virtual base
class, OF BOTH, `LimitCounter` and `OverflowCounter`, which may
cause a tiny performance penalty.
(How much depends on the implementation, usually its minimal,
eg. instead of two levels of indirection when calling a function
from the interface it may be three.)
From the viewpoint of the LSP `OverflowCounter` also IS NOT A
`LimitCounter`, though it shares most of its member function
names.
Compiling Program...
Standard Input:
Interactive Console
Text
Program is not being debugged. Click "Debug" button to start program in debug mode.
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