Comments on: Object-based programming in C

By: Edward Day

Edward Day — Thu, 01 Sep 2011 15:03:33 +0000

Hi your web page url: http://embeddedgurus.com/state-space/2008/01/object-based-programming-in-c appears to be redirecting to a completely different web-site when I click the home-page button. You may want to have this checked.

By: Holiday In Spain

Holiday In Spain — Wed, 03 Aug 2011 13:06:39 +0000

Hi friend,

Thanks for a interesting article.

Keep more coming as the quality is awesome

Thanks

Julie

By: Creative Web Design

Creative Web Design — Tue, 02 Aug 2011 00:27:22 +0000

Hey %author.

Thanks for the information you’ve put here, really useful advice.

Cheers

Phil

By: Frank Theile

Frank Theile — Thu, 03 Mar 2011 10:50:07 +0000

Hello Miro,

this is a very good paper! This is also the way Rhapsody generates C-code from UML models.

Although I didn’t use Rhapsody myself, I successfully used these ideas in an embedded system (a dosing pump). E.g. classes for the different operation modes are inherited from a base operation mode class. This helps to re-use code and improves decoupling of components.

By: Miro Samek

Miro Samek — Wed, 30 Jan 2008 00:32:00 +0000

Mike,Thanks for your comment!I agree with you that all survey results must be taken with a grain of salt. And certainly, shifts in the respondents' base to more hardware-oriented firmware developers could explain a lot of the seeming decline of C++.Even so, however, I believe that the genreal trend away from objects in embedded is real. And I claim it mostly because I see that tool vendors, such as I-Logix/Telelogic, pursue "C" programmers more aggresively than ever, expending significant resources in the process.As to the irrelevancy of objects in embedded software development, I obviously disagree. Object technology is the biggest advancement in software development since structured programming, as attested by thousands of books, countless articles, special OO conferences, and explosion of OO programming languages. Granted, embedded software development is different than programming for the desktop, but it’s not that different to completely render irrelevant the most valuable lessons people learned about software structure and code reuse.And sure, objects are everywhere in embedded designs. Tasks, events, state machines, timers, queues, data packets, are all objects. There is of course a lot of inheritance going on as well Take for example the popular Micro-C/OS RTOS that you’ve been teaching in Florida last week. One of the central elements of this RTOS’ design is the OS_EVENT data type, which represents an operating system event. OS_EVENT is a class with a constructor (OSEvent WaitListInit()), and member functions (OSEventTaskRdy(), OSEventTaskWait(), and OSEventTaskTO()). However, OS_EVENT is actually an abstract class that is only intended for inheritance and cannot be instantiated directly. OS_EVENT class is inherited by semaphores, message mailboxes, message queues, event flags, and so on, which all are classes with constructors, destructors, and member functions. All subclasses of OS_EVENT reuse the member functions from the superclass, which leads to substantial code reuse and better code structure.My point here is that good embedded designs use objects, whether they realize it or not. But of course, it’s easier if you do realize that you’re using objects because it spares you re-inventing the wheel, so that you can immediately benefit from all the body of knowledge about design principles, idioms, and patterns.

By: Michael Barr

Michael Barr — Thu, 24 Jan 2008 14:51:00 +0000

There are a couple of things here I feel worthy of comment. First, beware taking survey results and especially their year-over-year changes at face value. As a former editor of that very magazine I can tell you that there is a selection bias. Sure, they ask the same questions every year and via the same sampling process. But at each opportunity to add, replace, or pare readership, the folks who sell the ads in these free magazines typically select only those readers they think are most coveted by advertisers. This favors 32-bit over 8-bit, big teams over small, and even certain regions of the country.To be specific, as print circulation of ESD has declined in recent years these surveys have been distributed to a sample of readers of sister pub EETimes, which is much more likely to be read by EEs inclined toward electronics design.The second comment I have is that objects are not relevant to much of what embedded software developers do. (State machines are very relevant, of course.) But the only "objects" to be found are typically single instance peripherals. Lacking the need for class inheritance or dynamic allocation of object instances, embedded systems stand primarily to benefit from encapsulation.