Tag Archives: Polymorphism

Using final in C++ to improve performance

Posted on November 14, 2022 by Niall Cooling
Niall Cooling
Niall Cooling
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall Cooling
Latest posts by Niall Cooling (see all)

Dynamic polymorphism (virtual functions) is central to Object-Oriented Programming (OOP). Used well, it provides hooks into an existing codebase where new functionality and behaviour can (relatively) easily be integrated into a proven, tested codebase.

Subtype inheritance can bring significant benefits, including easier integration, reduced regression test time and improved maintenance.

However, using virtual functions in C++ brings a runtime performance overhead. This overhead may appear inconsequential for individual calls, but in a non-trivial real-time embedded application, these overheads may build up and […]

Posted in C/C++ Programming, Design Issues | Tagged , , , , , | 12 Comments

Bitesize Modern C++ : Override and Final

Posted on September 10, 2015 by Glennan Carnie
Glennan Carnie
Glennan Carnie
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.

He specialises in C++, UML, software modelling, Systems Engineering and process development.
Glennan Carnie
Latest posts by Glennan Carnie (see all)

Override specifier

In C++98 using polymorphic types can sometimes lead to head-scratching results:

On the face of it this code looks sound; indeed it will compile with no errors or warnings. However, when it runs the Base version of op() will be executed!

The reason? Derived’s version of op() is not actually an override of Base::op since int and long are considered different types (it’s actually a conversion between an int and a long, not a promotion)

The compiler is more than happy to […]

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Templates and polymorphism

Posted on July 10, 2014 by Glennan Carnie
Glennan Carnie
Glennan Carnie
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.

He specialises in C++, UML, software modelling, Systems Engineering and process development.
Glennan Carnie
Latest posts by Glennan Carnie (see all)

Introduction

Template functions and classes tend to cause consternation amongst programmers. The conversation tends to go something like this:

I understand the syntax of templates (although it’s ugly)
I get the idea of replacing function-like macros with template functions
I can see the application of template classes for containers
Most containers and generic functions are library code
I don’t write libraries
What’s the point of me using templates?

In this article we’re going to look at an application of templates beyond writing library code – replacing run-time polymorphism […]

Posted in C/C++ Programming | Tagged , , , , | 3 Comments

Inheritance, ABCs and Polymorphism

Posted on March 14, 2011 by Glennan Carnie
Glennan Carnie
Glennan Carnie
Technical Consultant at Feabhas Ltd
Glennan is an embedded systems and software engineer with over 20 years experience, mostly in high-integrity systems for the defence and aerospace industry.

He specialises in C++, UML, software modelling, Systems Engineering and process development.
Glennan Carnie
Latest posts by Glennan Carnie (see all)

Virtual functions

Virtual functions in C++ exist to maintain the consistent behaviour of polymorphism when accessing derived objects via base class pointers. (If that statement has made your head spin, I’d suggest reading this article before carrying on)

class Base
{
public:
virtual void v_op();
};

class Derived : public Base
{
public:
virtual void v_op();
}

I can access either a Base object or a Derived object via a Base pointer; and I should get the appropriate behaviour for the actual type of the object I’m pointed at:

Base* […]

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Polymorphism in C++

Posted on May 21, 2010 by Niall Cooling
Niall Cooling
Niall Cooling
Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.
Niall Cooling
Latest posts by Niall Cooling (see all)

The term polymorphism is central to most discussions in and around object oriented design and programming. However I find that many people are still confused or don’t have a complete understanding of the advantages and disadvantages of using polymorphism.

I have heard many different simplified definitions of the root term for polymorphism, usually relating to chemistry or biology. Rather than trying to justify the name, I’ll give you my very simplistic definition from a software perspective.  Simply put polymorphism means:

Multiple functions […]

Posted in C/C++ Programming | Tagged , , , , | 9 Comments