设计模式之-建造者模式

建造者模式将一个复杂对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示。
例如建造一个车， 宝马先建造车身， 发动机， 车窗， 车轮， 奔驰先造发动机， 车身，车轮， 车窗等等。对于客户来说， 知道造车工厂就可以了， 具体怎么造， 那是汽车工厂的事情。 
使用场景

     当创建复杂对象的算法独立于他的组成部分

     当构造的过程必须允许被构造对象有不同的表示时候

#include<iostream>
using namespace std;

class Builder {
public:
    virtual ~Builder() {};
    virtual void BuildEngine() =0;
    virtual void BuildWindow() =0;
    virtual void BuildWheel() =0;
    virtual void BuildChassis() =0;

};
class Ben : public Builder {
public:
    void BuildEngine() { cout << "Ben BuildEngine \n"; }
    void BuildWindow() { cout << "Ben BuildWindow\n"; }
    void BuildWheel() { cout << "Ben BuildWheel \n"; }
    void BuildChassis() { cout << "Ben BuildChassis"; }
};
class BMW : public Builder {
public:
    void BuildEngine() { cout << "BMW BuildEngine \n"; }
    void BuildWindow() { cout << "BMW BuildWindow\n"; }
    void BuildWheel() { cout << "BMW BuildWheel \n"; }
    void BuildChassis() { cout << "BMW BuildChassis\n"; }
};

class Direct {
public:
    Direct(Builder *pB) { pb = pB; }
    void Create() {
        pb->BuildEngine();
        pb->BuildWindow();
        pb->BuildChassis();
        pb->BuildWheel();
    }
private:
    Builder *pb;
};

int main(int argc, char* agrv[]) {
    Builder *pC = new BMW();
    Direct *pD = new Direct(pC);
    pD->Create();

    delete pD;
    delete pC;
    return 0;
}

备注：
手绘UML图

Makefile文件

# set CPUS for Linux or FreeBSD
CPUS := $(shell cat /proc/cpuinfo|grep -c processor)


GCC472_PATH=/usr/local/gcc-4.7.2
CXX := env LD_LIBRARY_PATH=$(GCC472_PATH)/lib:/usr/local/mpc/lib $(GCC472_PATH)/bin/g++
CXXFLAGS := -g3 -O2 -fno-strict-aliasing -Wall -Werror -fPIC \
-isystem /usr/local/include \
-isystem /usr/include

LDFLAGS := -pthread \
-L/usr/local/lib64/ \
-L/usr/local/lib/
RTFLAGS := \
-Wl,-rpath=.. \
-Wl,-rpath=/$(GCC472_PATH)/lib64

LIBS := -lpthread

SRC := $(wildcard *.cc)
OBJ := $(patsubst %.cc, %.o, $(SRC))
DEP := $(patsubst %.o, %.d, $(OBJ))

TARGET := main_test

all:
$(MAKE) -j$(CPUS) target

main_test: $(OBJ)
$(CXX) $^ -o $@ $(RTFLAGS) $(LDFLAGS) $(LIBS)


target: $(TARGET)

%.o : %.cc
$(CXX) -c $(CXXFLAGS) $< -o $@

%.d : %.cc
@$(CXX) -MM $< $(CXXFLAGS) | sed 's/$(notdir $*)\.o/$(subst /,\/,$*).o $(subst /,\/,$*).d/g' > $@

clean:
-rm -rf $(OBJ) $(TARGET) *.core $(DEP) *_unittest

test: all
./main_test

.PHONY: all target clean test