Ray's playground

摘要： The fundamental advice of this Item is to consider alternatives to virtual functions when searching for a design for the problem you're trying to solve. Here's a quick recap the alternatives we examined: Use the non-virtual interface idiom (NVI idiom), a form of the Template Method design pa 阅读全文

摘要： The ability to halt a process that is being debugged is achieved by settingbreakpoints. By halting the process, you are able to inspect variables, stackarguments, and memory locations without the process changing any of theirvalues before you can record them. Breakpoints are most definitely the mos. 阅读全文

摘要： 1>>>fromctypesimport*2>>>c_int()3c_long(0)4>>>c_char_p("helloworld!")5c_char_p('helloworld!')6>>>c_ushort(-5)7c_ushort(65531)8>>>seitz=c_char_p("lovespython")9>>>printseitz10c_char_p('lovespython')11>>> 阅读全文

摘要： Inheritance of interface is different from inheritance of implementation. Under public inheritance, derived classes always inherit base class interfaces. Pure virtual functions specify inheritance of interface only. Simple (impure) virtual functions specify inheritance of interface plus inheritance. 阅读全文

摘要： 1#import"MyDocument.h"2#import"DepartmentViewController.h"3#import"EmployeeViewController.h"45@implementationMyDocument67-(id)init8{9[superinit];10viewControllers=[[NSMutableArrayalloc]init];1112ManagingViewController*vc=[[DepartmentViewControlleralloc]init];13[vcsetMan 阅读全文

摘要： 1defmore(text,numlines=15):2lines=text.splitlines()3whilelines:4chunk=lines[:numlines]5lines=lines[numlines:]6forlineinchunk:7printline8iflinesandraw_input('More?')notin['y','Y']:9break1011if__name__=='__main__':12importsys13more(open(sys.argv[1]).read(),10)14 1>&g 阅读全文

摘要： Names in derived classes hide names in base classes. Under public inheritance, this is never desirable. To make hidden names visible again, employ using declarations or forwarding functions.1#include<iostream>2usingnamespacestd;34classBase5{6private:7intx;89public:10virtualvoidmf1()=0;11virtua 阅读全文

摘要： Public inheritance means "is-a." Everything that applies to base classes must also apply to derived classes, because every derived class object is a base class object. 阅读全文