• sclytrack pi.be (40/40) Jul 19 2006 I've only been using D sinds June 2006, I stumbled accross this today.
• Hasan Aljudy (5/61) Jul 19 2006 It's got to do with function overloading in the derived class.
• Lars Ivar Igesund (9/27) Jul 19 2006 It has to do with the overload rules in D, which are taken from C++. It
• sclytrack pi.be (4/31) Jul 19 2006 Yeah, I found it a bit confusing. I'm sure Walter has a reason for desig...
• Stewart Gordon (8/24) Jul 19 2006

sclytrack pi.be writes:

I've only been using D sinds June 2006, I stumbled accross this today.


Is this normal D behavior that int number() is no longer accessible from the
derived class while backupNumber still is? 

I can work around this, without problems. :-)

dmd v0.163




import std.stdio;


class BaseClass
{
protected:
int _number;
public:
int number()
{
return _number;
}

int backupNumber()
{
return _number;
}
}

class BaseDerived:BaseClass
{
public:
void number(int value)
{
_number = value + 1;
}
}


int main()
{
BaseDerived derived = new BaseDerived();
derived.number = 10;
writefln( derived.number );	//Error 

//main.d(35): function main.BaseDerived.number (int) does not match argument
types ()
//main.d(35): Error: expected 1 arguments, not 0
//main.d(35): voids have no value

return 0;
}

One day, I will have a real girlfriend.

Hasan Aljudy <hasan.aljudy gmail.com> writes:

sclytrack pi.be wrote:
 I've only been using D sinds June 2006, I stumbled accross this today.
 
 
 Is this normal D behavior that int number() is no longer accessible from the
 derived class while backupNumber still is? 
 
 I can work around this, without problems. :-)
 
 dmd v0.163

It's got to do with function overloading in the derived class.
When you overload number in Derived, you lose visibility to the other 
number method(s).

As for why is that? I don't know. Maybe to prevent possible confusion.

 
 
 
 
 import std.stdio;
 
 
 class BaseClass
 {
 protected:
 int _number;
 public:
 int number()
 {
 return _number;
 }
 
 int backupNumber()
 {
 return _number;
 }
 }
 
 class BaseDerived:BaseClass
 {
 public:
 void number(int value)
 {
 _number = value + 1;
 }
 }
 
 
 int main()
 {
 BaseDerived derived = new BaseDerived();
 derived.number = 10;
 writefln( derived.number );	//Error 
 
 //main.d(35): function main.BaseDerived.number (int) does not match argument
 types ()
 //main.d(35): Error: expected 1 arguments, not 0
 //main.d(35): voids have no value
 
 return 0;
 }
 

Lars Ivar Igesund <larsivar igesund.net> writes:

Hasan Aljudy wrote:

 
 
 sclytrack pi.be wrote:
 I've only been using D sinds June 2006, I stumbled accross this today.
 
 
 Is this normal D behavior that int number() is no longer accessible from
 the derived class while backupNumber still is?
 
 I can work around this, without problems. :-)
 
 dmd v0.163

 
 It's got to do with function overloading in the derived class.
 When you overload number in Derived, you lose visibility to the other
 number method(s).
 
 As for why is that? I don't know. Maybe to prevent possible confusion.

It has to do with the overload rules in D, which are taken from C++. It
turns out that the issues people find with this feature in D, isn't
particularly present when using C++, so people are quite often confused
with the current operation (which is quite opposite to how it works in
Java).

The solution in this case is to use alias to pull the symbol into the
namespace of the subclass:

alias BaseClass.number number;

sclytrack pi.be writes:

In article <e9l7d5$1g4j$1 digitaldaemon.com>, Lars Ivar Igesund says...
Hasan Aljudy wrote:

 
 
 sclytrack pi.be wrote:
 I've only been using D sinds June 2006, I stumbled accross this today.
 
 
 Is this normal D behavior that int number() is no longer accessible from
 the derived class while backupNumber still is?
 
 I can work around this, without problems. :-)
 
 dmd v0.163

 
 It's got to do with function overloading in the derived class.
 When you overload number in Derived, you lose visibility to the other
 number method(s).
 
 As for why is that? I don't know. Maybe to prevent possible confusion.

It has to do with the overload rules in D, which are taken from C++. It
turns out that the issues people find with this feature in D, isn't
particularly present when using C++, so people are quite often confused
with the current operation (which is quite opposite to how it works in
Java).

The solution in this case is to use alias to pull the symbol into the
namespace of the subclass:

alias BaseClass.number number;


Yeah, I found it a bit confusing. I'm sure Walter has a reason for designing it
this way, but is too busy to answer this.


Thanks for your reply, Sclytrack.

Stewart Gordon <smjg_1998 yahoo.com> writes:

Hasan Aljudy wrote:
 
 sclytrack pi.be wrote:
 I've only been using D sinds June 2006, I stumbled accross this today.
 
 Is this normal D behavior that int number() is no longer accessible 
 from the
 derived class while backupNumber still is?
 I can work around this, without problems. :-)
 
 dmd v0.163

 
 It's got to do with function overloading in the derived class.
 When you overload number in Derived, you lose visibility to the other 
 number method(s).
 
 As for why is that? I don't know. Maybe to prevent possible confusion.

<snip>

It carries over from C++ days.  AIUI the point is to avert a scenario 
whereby a base class can gain a new overload of the method name, and 
thereby cause a call to use this instead of your function in the derived 
class.  See

http://tinyurl.com/owwve

Stewart.