Re: Simple inheritance-template question

From:
Goran <goran.pusic@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 14 Apr 2011 04:58:01 -0700 (PDT)
Message-ID:
<600280e3-4c70-4492-a876-a305db5e4799@n2g2000prj.googlegroups.com>
On Apr 14, 1:19 pm, "crea" <n...@invalid.com> wrote:

"Goran" <goran.pu...@gmail.com> wrote in message

news:3ba65432-9aa1-4c9c-8326-59496b82f3e0@p3g2000vbv.googlegroups.com...
On Apr 14, 12:12 pm, "crea" <n...@invalid.com> wrote:
"I would simply make sure (through correct coding) that BB does use
DataHolder that has a pointer to BBData (not "plain" data) and then
use this:

class AA
{
  Data& GetData() { assert(m_data.data); return *m_data.data; }

}

class BB : public AA
{
  BBData& GetData() { return static_cast<BBData&>(AA::GetData(); }

};

Goran."

I was also thinking that first. But the problem is that inside AA I have
code like:
void AA::DoSomething()

{

...(a lot of code)

m_data.data.Add(new Data());

...(a lot of code)

}

So if I create a BB object and call this DoSomething , then it will creat=

e

Data-instance and not BBData. I know I could make DoSomething a virtual
fucntion , but DoSomething is *very* big function so I would rather now c=

opy

all of it to BB. Yes, I could then create a virtual function for only tha=

t

"Add"... :

void BB::AddData(..)
and then have virtual in AA:

virtual void AA::AddData(..). So now DoSomething becomes:

void AA::DoSomething()

{

...(a lot of code)

AddData(..);

...(a lot of code)

}

but AA has like 5 different this kind of fucntions. Shall I just create a
virtual function for all of them (5 of them)? I could obviously put them =

to

be private. But is there any easier way... this is doable, but needs to
override many functions.


(Not private, protected, you need to override).

Overrides seem^^^ to be trivial: create a different object type given
some parameters, so why not?

(^^^: I am guessing that after new Data() you actually put something
useful in that object).

Goran.

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