Interested to Buy Any Domain ? << Click Here >> for more details...
What is an action class?
- 1 Answers
- 1764 Views
- I also Faced
- E-Mail Answers
Answer / ritesh pal
The simplest and most obvious way to specify an action in C++ is to write a function. However, if the action has to be delayed, has to be transmitted 'elsewhere' before being performed, requires its own data, has to be combined with other actions, etc then it often becomes attractive to provide the action in the form of a class that can execute the desired action and provide other services as well.
Manipulators used with iostreams is an obvious example.
Explanation:
A common form of action class is a simple class containing just one virtual function.
class Action
{
public:
virtual int do_it( int )=0;
virtual ~Action( );
}
Given this, we can write code say a member that can store actions for later execution without using pointers to functions, without knowing anything about the objects involved, and without even knowing the name of the operation it invokes. For example:
class write_file : public Action
{
File& f;
public:
int do_it(int)
{
return fwrite( ).suceed( );
}
};
class error_message: public Action
{
response_box db(message.cstr( ),"Continue","Cancel","Retry");
switch (db.getresponse( ))
{
case 0: return 0;
case 1: abort();
case 2: current_operation.redo( );return 1;
}
};
A user of the Action class will be completely isolated from any knowledge of derived classes such as write_file and error_message.
| Is This Answer Correct ? | 0 Yes | 0 No |
What is array in c++ example?
What is class and structure in c++?
What is an Object/Instance?
Which one of the following describes characteristics of "protected" inheritance? a) The base class has access only to the public or protected members of the derived class. b) The derived class has non-public, inheritable, access to all but the private members of the base class. c) The derived class has access to all members of the base class. d) The private members of the base class are visible within the derived class. e) Public members of the derived class are privately accessible from the base class.
What does 7/9*9 equal ? a) 1 b) 0.08642 c) 0
Can we generate a C++ source code from the binary file?
Explain overriding.
What is abstraction in c++?
Explain shallow copy?
What are function prototypes?
Mention the storage classes in c++.
write a program in c++ to implement stack using functions in header file stack.h
STL 
