"Willy Denoyette [MVP]" wrote:

>
> "pradeep_TP" <pradee***@discussions.microsoft.com> wrote in message
> news:1F7FC440-E89A-4487-9E26-FA8AFF442214@microsoft.com...
> | Hi all,
> |
> | I was reading about MSIL and i came to know that there are some features
> of
> | CLR that can be only accessed by programming in IL. I want to know what
> are
> | these features which cannot be accessed by languages like c# or vb.net
> |
> | Thanks
> | pradeep_tp
>
> What exactly do you mean with "features of the CLR", MSIL allows you to do
> things which aren't possible/allowed to do in higher level languages, but as
> far as the CLR goes there is nothing that IL does what can't be done in C#
> for instance.
>
> Willy.
>
>
>

"pradeep_TP" <pradee***@discussions.microsoft.com> wrote in message
news:CF8B5B0D-0E9E-44E7-94E6-EC1A20A3FF4E@microsoft.com...
| Hi willy
|
| By saying "features of CLR" , I mean  CLR's facilties. As you have
| mentioned, what are those things which are allowed/possisble only through
| MSIL.
|
| thanks
| pradeep_tp
|
| "Willy Denoyette [MVP]" wrote:
|
| >
| > "pradeep_TP" <pradee***@discussions.microsoft.com> wrote in message
| > news:1F7FC440-E89A-4487-9E26-FA8AFF442214@microsoft.com...
| > | Hi all,
| > |
| > | I was reading about MSIL and i came to know that there are some
features
| > of
| > | CLR that can be only accessed by programming in IL. I want to know
what
| > are
| > | these features which cannot be accessed by languages like c# or vb.net
| > |
| > | Thanks
| > | pradeep_tp
| >
| > What exactly do you mean with "features of the CLR", MSIL allows you to
do
| > things which aren't possible/allowed to do in higher level languages,
but as
| > far as the CLR goes there is nothing that IL does what can't be done in
C#
| > for instance.
| >
| > Willy.
| >
| >
| >

"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MPG.1e332a3085fa441498ccdf@msnews.microsoft.com...
| Willy Denoyette [MVP] <willy.denoye***@telenet.be> wrote:
| > Oh, I see, but I'm afraid I can't answer this question because I don't
know
| > all languages that target the CLR.
| > If I restrict myself to C#, VB.NET and managed C++, all I can come up
with
| > is:
| > - managed exports, that is the possibility to expose managed functions
to
| > unmanaged callers.
| > - overloads of methods with covariant return types
|
| Do any of the languages allow you to modify a boxed value in place? For
| instance, if I had a struct:
|
| public struct Foo
| {
|    public int x;
| }
|
| and put that into an ArrayList, in C# I certainly wouldn't be able to
| modify the value in the list - I'd have to overwrite it with a new
| boxed value after unboxing and modifying the other one, if you see what
| I mean.
|
| My guess is that it's available in C++, but it doesn't hurt to know
| these things...
|

"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MPG.1e333cc1382d6d3898cce0@msnews.microsoft.com...
| Willy Denoyette [MVP] <willy.denoye***@telenet.be> wrote:
| > Don't know about other languages, but AFAIK the managed C++ language has
no
| > way to do it either and the compiler won't generate code to modify
| > "in-place" (AFIAK), at least not in a 'safe' context.
| > In an unsafe context, I guess there is, but the question is; if it's
more
| > efficient than an unbox/modify/box trip?
|
| I seem to remember testing it in a sample program by modifying some IL
| generated from C# - no need for unsafe code, it's just an IL unbox
| without a copy. I think it made a fairly significant difference, but
| only in a situation which is limited by this kind of operation
| happening a lot. Of course, generics solve this problem in a rather
| neater way anyway, if you're able to use 2.0 :)
|

"Mattias Sjögren" wrote:

> >Do any of the languages allow you to modify a boxed value in place?
>
> This works for me:
>
> // Old syntax
> __value struct Foo
> {
> public:
>     Foo(int x) { this->x = x; }
>     virtual String * ToString() { return __box(x)->ToString(); }
>     int x;
> };
>
> int main()
> {
>     Object *o = __box(Foo(42));
>     dynamic_cast<Foo*>(o)->x = 123;
>     Console::WriteLine(o);
>     return 0;
> }
>
> // New syntax, compiles with /clr:safe
> value struct Foo
> {
> public:
>     Foo(int x) { this->x = x; }
>     virtual String^ ToString() override { return x.ToString(); }
>     int x;
> };
>
> int main()
> {
>     Object ^o = Foo(42);
>     dynamic_cast<Foo^>(o)->x = 123;
>     Console::WriteLine(o);
>     return 0;
> }
>
>
> To add to the list of things you can't do in C#, VB or C++, I don't
> think any of them ever generates the tail. or cpblk IL instructions.
>
>
> Mattias
>
> --
> Mattias Sjögren [C# MVP]  mattias @ mvps.org
> http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> Please reply only to the newsgroup.
>

"Mattias Sjögren" <mattias.dont.want.spam@mvps.org> wrote in message
news:e2dVtHTGGHA.1424@TK2MSFTNGP12.phx.gbl...
| >Do any of the languages allow you to modify a boxed value in place?
|
| This works for me:
|
| // Old syntax
| __value struct Foo
| {
| public:
| Foo(int x) { this->x = x; }
| virtual String * ToString() { return __box(x)->ToString(); }
| int x;
| };
|
| int main()
| {
| Object *o = __box(Foo(42));
| dynamic_cast<Foo*>(o)->x = 123;
| Console::WriteLine(o);
| return 0;
| }
|
| // New syntax, compiles with /clr:safe
| value struct Foo
| {
| public:
| Foo(int x) { this->x = x; }
| virtual String^ ToString() override { return x.ToString(); }
| int x;
| };
|
| int main()
| {
| Object ^o = Foo(42);
| dynamic_cast<Foo^>(o)->x = 123;
| Console::WriteLine(o);
| return 0;
| }
|
|
| To add to the list of things you can't do in C#, VB or C++, I don't
| think any of them ever generates the tail. or cpblk IL instructions.
|
|
| Mattias
|
| --
| Mattias Sjögren [C# MVP]  mattias @ mvps.org
| http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
| Please reply only to the newsgroup.

"Mattias Sjögren" <mattias.dont.want.spam@mvps.org> wrote in message
news:uAgMaodGGHA.1552@TK2MSFTNGP10.phx.gbl...
| Willy,
|
| >it unboxes before modifying.
|
| Right, but to quote the spec for the unbox instruction:
|
| "Unlike box, which is required to make a copy of a value type for use
| in the object, unbox is not required to copy the value type from the
| object. Typically it simply computes the address of the value type
| that is already present inside of the boxed object."
|
|
| If a copy that was modified, Console::WriteLine(o) would print the
| original value 42.
|
|
| Mattias
|
| --
| Mattias Sjögren [C# MVP]  mattias @ mvps.org
| http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
| Please reply only to the newsgroup.