> On 03/31/11 15:00, Kjell Rilbe wrote:
>> Generally speaking, I feel it's completely wrong to add something to
>> an api only because some clients/users would expect it, unless it
>> actually does something useful in the api. it will only lead to extra
>> complexity and problems down the line.
>>
>> So, if the only reason to add queryInterface is to make Delphi users'
>> life easier I'd say no, even if I've been a huge Delphi fan ever since
>> version 1.
>
> BTW, what's a problem with writing using Delphi code RAII type for our
> interface without built-in into compiler support?
It is not a *big* problem, no. But it will be very convenient. See
simplified
example below :
1. Not compatible with IUnknown.
a) Our public header
class Interface
{
virtual int _cdecl addRef() = 0;
virtual int _cdecl release() = 0;
};
class IFoo : public Interface
{
virtual void _cdecl xxx() = 0;
};
b) Delphi declarations
type
IFBInterface = class
function addRef : Integer; abstract; cdecl;
function release : Integer; abstract; cdecl;
end;
IFoo = class(IFBInterface)
procedure xxx; abstract; cdecl;
end;
TFBInterface = class(TInterfacedObject, IFBInterface)
private:
// IInterface overloads
function _AddRef : Integer;
function _Release : Integer;
// IFBInterface methods
function addRef : Integer;
function release : Integer;
FFBIntf : IFBInterface;
public:
constructor Create(AFBIntf : IFBInterface);
end;
TFoo = class (TFBInterface, IFoo)
private:
FFoo : IFoo;
public
constructor Create(AFoo : IFoo);
// IFoo methods
procedure xxx;
end;
function TFBInterface._AddRef : Integer;
begin
return addRef;
end;
function TFBInterface._Release : Integer;
begin
return release;
end;
function TFBInterface.addRef : Integer;
begin
return FFBIntf.addRef;
end;
function TFBInterface.release : Integer;
begin
return FFBIntf.release;
end;
c) Delphi code example :
var
aFoo : IFoo;
begin
aFoo := TFoo.Create( fbGetMeFoo; )
aFoo.xxx;
end
2. If we became compatible with IUnknown
a) Our public header
class Interface
{
virtual int _stdcall queryInterface(...) = 0;
virtual int _stdcall addRef() = 0;
virtual int _stdcall release() = 0;
};
class IFoo : public Interface
{
virtual void _stdcall xxx() = 0;
};
b) Delphi declarations
IFoo = interface (IInterface)
procedure xxx; stdcall;
end;
c) Delphi code example :
var
aFoo : IFoo;
begin
aFoo := fbGetMeFoo;
aFoo.xxx;
end
Regards,
Vlad
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