Hi, Firstly - Sorry for a 2 day break! Secondly - Thanks a lot for such a beautiful explanation. It has certainly increased my knowledge.
Ooops!! After telling the entire story, I forgot the very basic thing - to ask my specific question. My question was (It may sound dumb!) : Why the value type instance was not boxed in the supplied code ? Regards, Girish Jain ----- Original Message ----- From: "Shawn A. Van Ness" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, November 24, 2004 1:46 AM Subject: Re: [ADVANCED-DOTNET] Methods Calls on value types > > IL_0002: ldloca.s V_0 // Load local variable address on to the stack > > Sounds like you understand, just fine. The CPU pushes the address of > the valuetype onto the stack, before making the function call. That's > a pointer, on the stack, *to* something else on the stack (but > slightly higher up). > > I think the real question you're asking is "why is this verifiable?" > Ordinarily, you're not allowed to go passing around pointers to things > on the stack... well, actually you are -- the above IL code > demonstrates that -- you're just not allowed to hold onto that pointer > beyond the life of what it points to. > > So, to consider why this is legal/verifiable, consider all the bad > things that method like ToString() might do with it. If it tries to > cache that arg0 in a field of type 'Object', the value will be boxed > (a copy made, on the heap)... fair enough. If it tries to copy arg0 > into a field of type 'Int32', it will be dereferenced and > bitwise-copied... again, no problemo. > > So, the lesson here is that pointers are not evil (unverifiable) > inandof themselves. It's what can be *done* with a pointer that's > evil and potentially unverifiable. Make sense? > > As long as the bytecode verifier can see that it's impossible for the > pointer to be copied to a place where it may outlast its > destination... it's all good. > > Cheers, > -Shawn > http://msdn.com/tabletpc > http://windojitsu.com > > =================================== > This list is hosted by DevelopMentorŪ http://www.develop.com > Some .NET courses you may be interested in: > > Essential .NET: building applications and components with C# > November 29 - December 3, in Los Angeles > http://www.develop.com/courses/edotnet > > View archives and manage your subscription(s) at http://discuss.develop.com > =================================== This list is hosted by DevelopMentorŪ http://www.develop.com Some .NET courses you may be interested in: Essential .NET: building applications and components with C# November 29 - December 3, in Los Angeles http://www.develop.com/courses/edotnet View archives and manage your subscription(s) at http://discuss.develop.com
