Sure, we do that

The DirectX video driver interface for Windows 95 had a method that each driver exposed called something like “DoesDriverSupport(REFGUID guidCapability)” where we handed it a capability GUID and it said whether or not that feature was supported. There were various capability GUIDs defined, things like GUID_CanStretchAlpha to ask the driver whether it was capable of stretching…

50

Orkut’s privacy policy and terms of service

It was bound to happen sooner or later. I was invited to join Orkut. But before clicking Submit, I always read the fine print: their Terms of Service and their Privacy Policy. (Oh great, you have to have scripting enabled just to read their Terms of Service and Privacy Policy!) Notice, for example, the terms…

23

Answer to exercise: Pointer to member function cast

Yesterday’s exercise asked you to predict and explain the codegen for the following fragment: class Base1 { int b1; void Base1Method(); }; class Base2 { int b2; void Base2Method(); }; class Derived : public Base1, Base2 { int d; void DerivedMethod(); }; class Derived2 : public Base3, public Derived { }; void (Derived::*pfnDerived)(); void (Derived2::*pfnDerived2();…

3

I think this counts as having come full circle

First, ABBA rises to stardom in their native Sweden with Ring, Ring. They then win the Eurovision Song Contest with Waterloo, which is also recorded in English, French, German, and probably Spanish. Twenty-five years later, the English-language musical Mamma-Mia premieres in London and subsequently spreads through large portions of the world not yet civilized enough…

4

Pointers to member functions are very strange animals

Pointers to member functions are very strange animals. Warning: The discussion that follows is specific to the way pointers to member functions are implemented by the Microsoft Visual C++ compiler. Other compilers may do things differently. Well, okay, if you only use single inheritance, then pointers to member functions are just a pointer to the…

19

Adjustor thunks

Yesterday we learned about the layout of COM objects and I hinted at “adjustor thunks”. If you find yourself debugging in disassembly, you’ll sometimes find strange little functions called “adjustor thunks”. Let’s take another look at the object we laid out last time: class CSample : public IPersist, public IServiceProvider { public: // *** IUnknown…

15

The layout of a COM object

The Win32 COM calling convention specifies the layout of the virtual method table (vtable) of an object. If a language/compiler wants to support COM, it must lay out its object in the specified manner so other components can use it. It is no coincidence that the Win32 COM object layout matches closely the C++ object…

39

The Glass Engine and Ishkur’s Guide to Electronic Music

The Glass Engine is an interactive guide to the music of Philip Glass, organized by… um… at least they’re organized. By something. Bizarre yet oddly compelling. (Perhaps if we ask nicely, we can get Marc Miller to tell the story of the time he actually met Philip Glass…) In a similar vein, a friend of…

4

Answers to exercises – mismatching new/delete

Answers to yesterday’s exercises: What happens if you allocate with scalar “new” and free with vector “delete[]”? The scalar “new” will allocate a single object with no hidden counter. The vector “delete[]” will look for the hidden counter, which isn’t there, so it will either crash (accessing nonexistent memory) or grab a random number and…

13

Mismatching scalar and vector new and delete

In a previous entry I alluded to the problems that can occur if you mismatch scalar “new” with vector “delete[]” or vice versa. There is a nice description of C++ memory management in C++ Gotchas: Avoiding Common Problems in Coding and Design on www.informit.com, and I encourage you to read at least the section titled…

16