digitalmars.D.learn - C++ cast to D cast

BLS (24/24) Sep 22 2007 Hi, I need some advice regarding "how to translate C++ casts into D" cas...

Bill Baxter (6/32) Sep 22 2007 I would guess

BLS (3/41) Sep 22 2007 Thanks Bill. Yep, need more coffee

BLS (11/11) Sep 22 2007 Hi Bill.

Bill Baxter (7/22) Sep 22 2007 The problem I see is that cast for classes in D is like dynamic_cast<>

BLS (7/32) Sep 22 2007 You mean

Jarrett Billingsley (3/5) Sep 22 2007 Yessir.

Bill Baxter (5/12) Sep 22 2007 Yes that's what I meant, but I have no idea if it works. It was just a

Jarrett Billingsley (18/30) Sep 23 2007 class A

BLS (8/48) Sep 23 2007 Thanks !

Jarrett Billingsley (3/10) Sep 23 2007 Done.

BLS (5/18) Sep 23 2007 Have to sleep, guess I'll spend myself a bottle of beer now, what

BLS <nanali nospam-wanadoo.fr> writes:

Hi, I need some advice regarding "how to translate C++ casts into D" casts.
As you can see the there are a lot within the return Statement.

class CGDI // C++
{
public:
   HDC m_hDC;
public:

   HFONT SelectFont(HFONT hFont)
   {
   return ((HFONT)::SelectObject((m_hDC), (HGDIOBJ)(HFONT)(hFont)));
   }
   HFONT SelectObject(CFont cf)
   {
    if (IsValidHandle())
     return (HFONT) ::SelectObject(m_hDC,(HFONT)cf.GetFont());
     return NULL;
   }
}
I guess :
   return (cast(HFONT)SelectObject(cast(m_hDC), 
cast(HGDIOBJ)cast(HFONT)cast(hFont)));
But it makes no sense to me. Can you offer me some advice ?

Many thanks in advance? and sorry about my ignorance ...
Bjoern

Sep 22 2007

Bill Baxter <dnewsgroup billbaxter.com> writes:

BLS wrote:
 Hi, I need some advice regarding "how to translate C++ casts into D" casts.
 As you can see the there are a lot within the return Statement.
 
 class CGDI // C++
 {
 public:
   HDC m_hDC;
 public:
 
   HFONT SelectFont(HFONT hFont)
   {
   return ((HFONT)::SelectObject((m_hDC), (HGDIOBJ)(HFONT)(hFont)));
   }
   HFONT SelectObject(CFont cf)
   {
    if (IsValidHandle())
     return (HFONT) ::SelectObject(m_hDC,(HFONT)cf.GetFont());
     return NULL;
   }
 }
 I guess :
   return (cast(HFONT)SelectObject(cast(m_hDC), 
 cast(HGDIOBJ)cast(HFONT)cast(hFont)));
 But it makes no sense to me. Can you offer me some advice ?

I would guess
    return (cast(HFONT)SelectObject(m_hDC, cast(HGDIOBJ)cast(HFONT)hFont));

It's just a function call -- SelectObject(m_hDC,hFont)

 
 Many thanks in advance? and sorry about my ignorance ...

Maybe you just need some sleep?  :-)

--bb

Sep 22 2007

BLS <nanali nospam-wanadoo.fr> writes:

Bill Baxter schrieb:
 BLS wrote:
 Hi, I need some advice regarding "how to translate C++ casts into D" 
 casts.
 As you can see the there are a lot within the return Statement.

 class CGDI // C++
 {
 public:
   HDC m_hDC;
 public:

   HFONT SelectFont(HFONT hFont)
   {
   return ((HFONT)::SelectObject((m_hDC), (HGDIOBJ)(HFONT)(hFont)));
   }
   HFONT SelectObject(CFont cf)
   {
    if (IsValidHandle())
     return (HFONT) ::SelectObject(m_hDC,(HFONT)cf.GetFont());
     return NULL;
   }
 }
 I guess :
   return (cast(HFONT)SelectObject(cast(m_hDC), 
 cast(HGDIOBJ)cast(HFONT)cast(hFont)));
 But it makes no sense to me. Can you offer me some advice ?

 
 I would guess
    return (cast(HFONT)SelectObject(m_hDC, cast(HGDIOBJ)cast(HFONT)hFont));
 
 It's just a function call -- SelectObject(m_hDC,hFont)
 
 Many thanks in advance? and sorry about my ignorance ...

 
 Maybe you just need some sleep?  :-)
 
 --bb

Thanks Bill. Yep, need more coffee
Bjoern

Sep 22 2007

BLS <nanali nospam-wanadoo.fr> writes:

Hi Bill.
Just something Regan and I allready have discussed ... but we are not 
sure about .

C++
CWin* pActive= 
reinterpret_cast<CWin*>((HWND)::GetWindowLong(msg.hwnd,GWL_USERDATA)); 


D
CWin pActive = cast(CWin) cast(HWND)GetWindowLong(msg.hwnd,GWL_USERDATA);

where CWin is a class.
The problem here is that pActive in D is a reference.
Bjoern

Sep 22 2007

Bill Baxter <dnewsgroup billbaxter.com> writes:

BLS wrote:
 Hi Bill.
 Just something Regan and I allready have discussed ... but we are not 
 sure about .
 
 C++
 CWin* pActive= 
 reinterpret_cast<CWin*>((HWND)::GetWindowLong(msg.hwnd,GWL_USERDATA));
 
 D
 CWin pActive = cast(CWin) cast(HWND)GetWindowLong(msg.hwnd,GWL_USERDATA);
 
 where CWin is a class.
 The problem here is that pActive in D is a reference.
 Bjoern
 

The problem I see is that cast for classes in D is like dynamic_cast<> 
in C++.  It will return null if the typeinfo system doesn't think HWND 
is a base class of CWin.

Maybe there's some way to disable that, like by casting to void* first? 
   Or maybe it's smarter than I'm thinking.

--bb

Sep 22 2007

BLS <nanali nospam-wanadoo.fr> writes:

Bill Baxter schrieb:
 BLS wrote:
 Hi Bill.
 Just something Regan and I allready have discussed ... but we are not 
 sure about .

 C++
 CWin* pActive= 
 reinterpret_cast<CWin*>((HWND)::GetWindowLong(msg.hwnd,GWL_USERDATA));

 D
 CWin pActive = cast(CWin) cast(HWND)GetWindowLong(msg.hwnd,GWL_USERDATA);

 where CWin is a class.
 The problem here is that pActive in D is a reference.
 Bjoern

 
 The problem I see is that cast for classes in D is like dynamic_cast<> 
 in C++.  It will return null if the typeinfo system doesn't think HWND 
 is a base class of CWin.
 
 Maybe there's some way to disable that, like by casting to void* first? 
   Or maybe it's smarter than I'm thinking.
 
 --bb

You mean

CWin pActive = cast(CWin)cast(void*) 
cast(HWND)GetWindowLong(msg.hwnd,GWL_USERDATA);
???
Thanks
Bjoern

Sep 22 2007

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"BLS" <nanali nospam-wanadoo.fr> wrote in message 
news:fd2v57$1ueb$1 digitalmars.com...

 CWin pActive = cast(CWin)cast(void*) 
 cast(HWND)GetWindowLong(msg.hwnd,GWL_USERDATA);

Yessir.

Sep 22 2007

Bill Baxter <dnewsgroup billbaxter.com> writes:

Jarrett Billingsley wrote:
 "BLS" <nanali nospam-wanadoo.fr> wrote in message 
 news:fd2v57$1ueb$1 digitalmars.com...
 
 CWin pActive = cast(CWin)cast(void*) 
 cast(HWND)GetWindowLong(msg.hwnd,GWL_USERDATA);

 
 Yessir. 

Yes that's what I meant, but I have no idea if it works.  It was just a 
guess.  Jarrett you can confirm that that avoids the runtime check in 
the cast?

--bb

Sep 22 2007

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"Bill Baxter" <dnewsgroup billbaxter.com> wrote in message 
news:fd3tfr$8i6$2 digitalmars.com...
 Jarrett Billingsley wrote:
 "BLS" <nanali nospam-wanadoo.fr> wrote in message 
 news:fd2v57$1ueb$1 digitalmars.com...

 CWin pActive = cast(CWin)cast(void*) 
 cast(HWND)GetWindowLong(msg.hwnd,GWL_USERDATA);

 Yessir.

 Yes that's what I meant, but I have no idea if it works.  It was just a 
 guess.  Jarrett you can confirm that that avoids the runtime check in the 
 cast?

 --bb

class A
{

}

class B
{

}

void main()
{
    A a = new A();
    B b = cast(B)cast(void*)a;
    B b2 = cast(B)a;

    Stdout.formatln("{:X8} {:X8}", cast(void*)b, cast(void*)b2);
}

This prints out (something like)

0012AB60 00000000

So yes, the cast(B)cast(void*) avoids a runtime check.

Sep 23 2007

BLS <nanali nospam-wanadoo.fr> writes:

Jarrett Billingsley schrieb:
 "Bill Baxter" <dnewsgroup billbaxter.com> wrote in message 
 news:fd3tfr$8i6$2 digitalmars.com...
 Jarrett Billingsley wrote:
 "BLS" <nanali nospam-wanadoo.fr> wrote in message 
 news:fd2v57$1ueb$1 digitalmars.com...

 CWin pActive = cast(CWin)cast(void*) 
 cast(HWND)GetWindowLong(msg.hwnd,GWL_USERDATA);

 Yessir.

 Yes that's what I meant, but I have no idea if it works.  It was just a 
 guess.  Jarrett you can confirm that that avoids the runtime check in the 
 cast?

 --bb

 
 class A
 {
 
 }
 
 class B
 {
 
 }
 
 void main()
 {
     A a = new A();
     B b = cast(B)cast(void*)a;
     B b2 = cast(B)a;
 
     Stdout.formatln("{:X8} {:X8}", cast(void*)b, cast(void*)b2);
 }
 
 This prints out (something like)
 
 0012AB60 00000000
 
 So yes, the cast(B)cast(void*) avoids a runtime check. 
 

Thanks !
Jarret, do you see a chance to place your solution, as well as comments at
http://www.prowiki.org/wiki4d/wiki.cgi?PortingOverview
Porting Code from C++ to D
(Hope I am not asking for too much, but the more you are going into 
details the more ... You know :)
Bjoern

Sep 23 2007

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"BLS" <nanali nospam-wanadoo.fr> wrote in message 
news:fd6g6h$pev$1 digitalmars.com...
 Thanks !
 Jarret, do you see a chance to place your solution, as well as comments at
 http://www.prowiki.org/wiki4d/wiki.cgi?PortingOverview
 Porting Code from C++ to D
 (Hope I am not asking for too much, but the more you are going into 
 details the more ... You know :)
 Bjoern

Done.

Sep 23 2007

BLS <nanali nospam-wanadoo.fr> writes:

Jarrett Billingsley schrieb:
 "BLS" <nanali nospam-wanadoo.fr> wrote in message 
 news:fd6g6h$pev$1 digitalmars.com...
 Thanks !
 Jarret, do you see a chance to place your solution, as well as comments at
 http://www.prowiki.org/wiki4d/wiki.cgi?PortingOverview
 Porting Code from C++ to D
 (Hope I am not asking for too much, but the more you are going into 
 details the more ... You know :)
 Bjoern

 
 Done. 
 
 

Have to sleep, guess I'll spend myself a bottle of beer now, what 
remains :  beeristasty = Muchas.Gracias.Hombre()
Bjoern

(I Do not speak spanish)

Sep 23 2007

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