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digitalmars.D - Did typedefs break code?

reply Mehrdad <wfunction hotmail.com> writes:
I just realized some of my code broke because of the (apparent?) changes 
to typedef.

I had something like:

    extern(Windows) void Foo(HANDLE h);

    const HANDLE h = CreateFile(...);
    Foo(h);

which now broke because Foo's parameter can no longer be const (since 
HANDLE is now an alias for void*, and so const HANDLE means 
const(void*), which can't be cast to void*).

Obviously, I can make the variable non-const to solve the problem, but 
like, was the change to typedef really necessary? Is there a plan to get 
around problems like these in the long term?
Sep 10 2011
next sibling parent Mehrdad <wfunction hotmail.com> writes:
On 9/10/2011 5:11 PM, Mehrdad wrote:
 I just realized some of my code broke because of the (apparent?) 
 changes to typedef.

 I had something like:

    extern(Windows) void Foo(HANDLE h);

    const HANDLE h = CreateFile(...);
    Foo(h);

 which now broke because Foo's parameter can no longer be const (since 
 HANDLE is now an alias for void*, and so const HANDLE means 
 const(void*), which can't be cast to void*).

 Obviously, I can make the variable non-const to solve the problem, but 
 like, was the change to typedef really necessary? Is there a plan to 
 get around problems like these in the long term?

HANDLE h; property HANDLE handle() const { return h; } because you can't return const(void*) as void*... so frustrating. :(
Sep 10 2011
prev sibling next sibling parent Jonathan M Davis <jmdavisProg gmx.com> writes:
On Saturday, September 10, 2011 17:11:56 Mehrdad wrote:
 I just realized some of my code broke because of the (apparent?) changes
 to typedef.
 
 I had something like:
 
     extern(Windows) void Foo(HANDLE h);
 
     const HANDLE h = CreateFile(...);
     Foo(h);
 
 which now broke because Foo's parameter can no longer be const (since
 HANDLE is now an alias for void*, and so const HANDLE means
 const(void*), which can't be cast to void*).
 
 Obviously, I can make the variable non-const to solve the problem, but
 like, was the change to typedef really necessary? Is there a plan to get
 around problems like these in the long term?

typedef is being removed from the language entirely. In its place we currently have alias and we will have a struct of some kind in Phobos (probably called Typedef or TypeDef) which will allow for something similar to typedef but with a finer grain of control over which conversions are implicit and which are explicit. I believe that typedef stuff was removed from Phobos in several places recently in preparation for the removal of typedef from the language. If that's causing problems, then they need to be identified and sorted out one way or another. Once we have an implementation of Typedef in Phobos is probably when we'll actually deprecate typedef. - Jonathan M Davis
Sep 10 2011
prev sibling parent "Daniel Murphy" <yebblies nospamgmail.com> writes:
"Mehrdad" <wfunction hotmail.com> wrote in message 
news:j4gucr$289g$1 digitalmars.com...
I just realized some of my code broke because of the (apparent?) changes to 
typedef.

 I had something like:

    extern(Windows) void Foo(HANDLE h);

    const HANDLE h = CreateFile(...);
    Foo(h);

The fact that const(HANDLE) implicitly converted to HANDLE is a bug in dmd. You can insert casts if you still want the same broken behaviour with alias. Apart from that, typedef has been 'unofficailly' deprecated for some time, and removed from (most of) the online documentation. Hopefully soon it will be officially deprecated in the language, giving a deprecation error when used.
Sep 10 2011