Comments on: Object-Oriented Thinking Part Two http://beej.us/blog/2010/01/object-oriented-thinking-part-two/ Tech and Programming Fun Tue, 07 Feb 2012 18:52:43 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: beej http://beej.us/blog/2010/01/object-oriented-thinking-part-two/comment-page-1/#comment-152 beej Tue, 02 Feb 2010 21:12:27 +0000 http://www.beej.us/blog/?p=116#comment-152 <a href="#comment-151" rel="nofollow">@Xerion</a> Yes, there certainly is a loss, since it's an indirect jump rather than a direct one. (That is, you need to look up in a table which function to jump to, because the instance might actually be a derived class that has overridden one of the base class's methods.) Even though a memory lookup (and possible cache miss) is something to consider, in this modern day of really fast machines, it's less and less of a practical issue, and most people just ignore it. (I mean, if you're running Java, you're already not at your peak efficiency compared to, say, assembly language, and that's okay!) But if utmost speed is of the essence in some inner loop or something, you might not want to call a virtual function. @Xerion Yes, there certainly is a loss, since it’s an indirect jump rather than a direct one. (That is, you need to look up in a table which function to jump to, because the instance might actually be a derived class that has overridden one of the base class’s methods.)

Even though a memory lookup (and possible cache miss) is something to consider, in this modern day of really fast machines, it’s less and less of a practical issue, and most people just ignore it. (I mean, if you’re running Java, you’re already not at your peak efficiency compared to, say, assembly language, and that’s okay!)

But if utmost speed is of the essence in some inner loop or something, you might not want to call a virtual function.

]]> By: Xerion http://beej.us/blog/2010/01/object-oriented-thinking-part-two/comment-page-1/#comment-151 Xerion Tue, 02 Feb 2010 20:57:58 +0000 http://www.beej.us/blog/?p=116#comment-151 Since my enlightenment to OOP I've used inheritance a great deal in my projects. One thing that I heard somewhere, was that there is a performance loss for using virtual functions. Have any thoughts about this? Since my enlightenment to OOP I’ve used inheritance a great deal in my projects. One thing that I heard somewhere, was that there is a performance loss for using virtual functions. Have any thoughts about this?

]]> By: Beej's Bit Bucket » Object-Oriented Thinking, Part One http://beej.us/blog/2010/01/object-oriented-thinking-part-two/comment-page-1/#comment-87 Beej's Bit Bucket » Object-Oriented Thinking, Part One Fri, 22 Jan 2010 21:42:26 +0000 http://www.beej.us/blog/?p=116#comment-87 [...] (This is continued in Object-Oriented Thinking Part Two.) [...] [...] (This is continued in Object-Oriented Thinking Part Two.) [...]

]]>