Design Patterns. It has been highly influential to the field of software engineering and is regarded as an important source for object-oriented design theory and practice.
More than 500,000 copies have been sold in English and in 13 other languages. The authors are often referred to as the Gang of Four (GoF).[1] History[edit] Introduction, Chapter 1[edit] Chapter 1 is a discussion of object-oriented design techniques, based on the authors' experience, which they believe would lead to good object-oriented software design, including: clients remain unaware of the specific types of objects they use, as long as the object adheres to the interfaceclients remain unaware of the classes that implement these objects; clients only know about the abstract class(es) defining the interface Use of an interface also leads to dynamic binding and polymorphism, which are central features of object-oriented programming. The authors admit that delegation and parameterization are very powerful but add a warning: Formatting[edit] Overloading Virtual Functions.
Index.jsp?topic=%2Fcom.ibm.xlcpp8a.doc%2Flanguage%2Fref%2Fcplr139. Showthread. OOP03-CPP. Prefer not to overload virtual functions - C++ Secure Coding Practices. Overloading of virtual functions tends to defeat polymorphism and introduce unnecessary complexity into a class hierarchy. Non-Compliant Code Examples Consider a simple hierarchy with an update capability. This design has a legal but unfortunate mismatch between overloading and overriding. The derived class MyThing declares an update function that overrides one of the inherited update functions, but hides both of them. The result is that a MyThing object exhibits different behavior depending on whether it is manipulated as a Thing or as a MyThing. In this piece of code, it is likely that its author assumed the call mt->update( 12.3 ) would bind to Thing::update (as it would in Java) rather than MyThing::update.
The approach of requiring a derived class to override all of a set of overloaded virtual functions solves the problem at a technical level. Compliant Solution (overloading) It's best to avoid overloading virtual functions. Compliant Solution (forwarding) Exceptions Risk Assessment. What your mother never told you Updated! [23.6] Okay, but is there a way to simulate that behavior as if dynamic binding worked on the this object within my base class's constructor?
Yes: the Dynamic Binding During Initialization idiom (AKA Calling Virtuals During Initialization). To clarify, we're talking about this situation: This FAQ shows some ways to simulate dynamic binding as if the calls made in Base's constructor dynamically bound to the this object's derived class. The ways we'll show have tradeoffs, so choose the one that best fits your needs, or make up another. The first approach is a two-phase initialization. The only remaining issues are determining where to call Phase I and where to call Phase II. The first variation is simplest initially, though the code that actually wants to create objects requires a tiny bit of programmer self-discipline, which in practice means you're doomed. In this variation, the code that is creating the object explicitly executes both phases. The Derived class is also easy to implement: