Comments on: How inheritance, encapsulation and polymorphism work in C++

By: Alexander Sandler

Alexander Sandler — Mon, 31 Aug 2009 07:50:23 +0000

@San This is exactly what I've written.

Reply - @San<\/a>\r\nThis is exactly what I\'ve written.'); return false;">Quote

By: San

San — Fri, 28 Aug 2009 11:29:45 +0000

I don't think it's the constructor that fill the virtual method table. In fact, an object just embeds a pointer to a virtual method table. All virtual method tables are built and filled by the compiler. The construct just direct the pointer embedded in the object to a proper method table.

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By: Andre Goddard Rosa

Andre Goddard Rosa — Mon, 27 Jul 2009 01:23:15 +0000

@Alexander Sandler - Thank you! :)

Reply - @Alexander Sandler<\/a> - Thank you! :)'); return false;">Quote

By: Alexander Sandler

Alexander Sandler — Sun, 26 Jul 2009 08:15:40 +0000

Originally Posted By Andre Goddard Rosa

Hi, Alexander! First of all, your website is really _really_ great! After I found it, it became irresistible to read it all completely. Please keep up the nice work! You talk about so many interesting subjects, it's so nice to have all this information on one place.

Thanks! :-)

I have two things to say, besides praising your website: 1) I wonder where you get all information. Is it by reading source code or you have some books to recommend? Perhaps it would be welcome a small topic with some nice references;

It's all kinds of places. This one in particular is a result of a research I did. This topic got me interested and I investigated it. Most of the time it comes from things that I for the company I work for.

2) On picture inheritance3.png, the one which depicts A, B and C internal class representation, I think you missed C::set_c() method on C's second vtable;

I guess it's kind of less relevant here so I dropped it.

And another question... Which program did you use for making those nice diagrams?

I am sorry to say this but this is MS. Word 2007. 2007 version in particular has a couple of features that allow you to draw diagrams like this. Although, I think OpenOffice 3.1 now has them too.

Reply - Originally Posted By Andre Goddard Rosa<\/a>

Hi, Alexander!\r\n\r\nFirst of all, your website is really _really_ great!\r\nAfter I found it, it became irresistible to read it all completely.\r\nPlease keep up the nice work! You talk about so many interesting subjects, it\'s so nice to have all this information on one place.<\/blockquote> Thanks! :-)\r\n\r\n
I have two things to say, besides praising your website:\r\n\r\n1) I wonder where you get all information. Is it by reading source code or you have some books to recommend? Perhaps it would be welcome a small topic with some nice references;<\/blockquote>\r\n\r\nIt\'s all kinds of places. This one in particular is a result of a research I did. This topic got me interested and I investigated it. Most of the time it comes from things that I for the company I work for.\r\n\r\n
2) On picture inheritance3.png, the one which depicts A, B and C internal class representation, I think you missed C::set_c() method on C\'s second vtable;<\/blockquote>\r\nI guess it\'s kind of less relevant here so I dropped it. \r\n\r\n
And another question... Which program did you use for making those nice diagrams?<\/blockquote>\r\nI am sorry to say this but this is MS. Word 2007. 2007 version in particular has a couple of features that allow you to draw diagrams like this. Although, I think OpenOffice 3.1 now has them too.'); return false;">Quote

By: Andre Goddard Rosa

Andre Goddard Rosa — Sat, 25 Jul 2009 04:07:55 +0000

Sorry for the interspersed comment, I should say the c_member is missing from more than one picture. And I'd like to take the opportunity to say that I've subscribed to your website and suggest that after you come up with even more content, you could organize and make a book with all this information. Is this your plan already?

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By: Andre Goddard Rosa

Andre Goddard Rosa — Sat, 25 Jul 2009 03:50:24 +0000

Ahhhn, c_member is also missing from that very same picture.

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By: Andre Goddard Rosa

Andre Goddard Rosa — Sat, 25 Jul 2009 03:47:40 +0000

Hi, Alexander! First of all, your website is really _really_ great! After I found it, it became irresistible to read it all completely. Please keep up the nice work! You talk about so many interesting subjects, it's so nice to have all this information on one place. I have two things to say, besides praising your website: 1) I wonder where you get all information. Is it by reading source code or you have some books to recommend? Perhaps it would be welcome a small topic with some nice references; 2) On picture inheritance3.png, the one which depicts A, B and C internal class representation, I think you missed C::set_c() method on C's second vtable; And another question... Which program did you use for making those nice diagrams?

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By: Destillat KW27 | duetsch.info

Destillat KW27 | duetsch.info — Fri, 03 Jul 2009 12:48:50 +0000

[...] How inheritance, encapsulation and polymorphism work in C++ [...]

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By: Alexander Sandler

Alexander Sandler — Sun, 24 May 2009 07:53:43 +0000

@Amirhossein Jabbari It depends. If you are accessing virtual method, then pointers should point to two difference instances - check out polymorphism and multiple inheritance section of the article to see how it works. If methods you are trying to access are regular methods, then it will call a method depending on type of object whose method you are calling. For instance, in the same example you've referenced, lets say we add a non-virtual method to class A and overload it in class C. Then we call it via object c and via a1. First time it will call C's method. Second time it will call A's method. Hope it answers your question. Thanks for visiting and please come again :-)

Reply - @Amirhossein Jabbari<\/a>\r\nIt depends. If you are accessing virtual method, then pointers should point to two difference instances - check out polymorphism and multiple inheritance section of the article to see how it works.\r\n\r\nIf methods you are trying to access are regular methods, then it will call a method depending on type of object whose method you are calling. \r\nFor instance, in the same example you\'ve referenced, lets say we add a non-virtual method to class A and overload it in class C. Then we call it via object c and via a1. First time it will call C\'s method. Second time it will call A\'s method.\r\n\r\nHope it answers your question. Thanks for visiting and please come again :-)'); return false;">Quote

By: Amirhossein Jabbari

Amirhossein Jabbari — Sat, 23 May 2009 18:54:48 +0000

After a few months I'm back to your wonderful article again and It seems it still have something new for me to learn. When using different types of casting in Multiple Inheritance example, I understand the difference between b1 and b2 in the sense that they point to different locations of the instance of C class. However, the question is what is the difference between these two pointers when one wants to access the member functions of the class C?

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