Re: Returning Nulls in Templates

From:

Noah Roberts <dont@email.me>

Newsgroups:

comp.lang.c++

Date:

Tue, 22 Mar 2011 09:39:59 -0700

Message-ID:

<4d88d0d3$0$17187$cc2e38e6@news.uslec.net>

On 3/21/2011 7:24 PM, Ruben Safir wrote:

On Mon, 21 Mar 2011 10:51:26 -0700, Noah Roberts wrote:

On 3/21/2011 10:01 AM, Ruben Safir wrote:

On Sun, 20 Mar 2011 13:53:17 +0000, Leigh Johnston wrote:

On 20/03/2011 09:17, Alf P. Steinbach /Usenet wrote:

* Ruben Safir, on 20.03.2011 06:37:

inline unk value();

It's not necessary to designate the method as 'inline', since it's in
a template.

On the other hand you should have a 'const' at the end there.

inline unk& value_ref();
inline void value(unk);

When you have exposed a member in all ways possible, and that's
roughly what you have done here, what's the point of having that
member non-'private'?

In this case, nothing.

Remove the accessor and modifier stuff. Just make that value
'public'.

I disagree; instead I would do:

const unk& value() const;
unk& value();
void set_value(const unk&);

/Leigh

If I define value() as a const returning a const reference, then I
can't change the value when using the operator[] and I'd think defeats
the purpose of making it a reference in the first place ..

mylist[2] = mylust[3];

I broke value() into two different methods, one returning the reference

unk Node::value() const{
return value_;
}

unk& Node::value_ref(){
return value_;
}

In case you are not aware, you can override based on const-ness. For
example:

unk Node::value() const { return value_; } unk& Node::value() { return
value_; }

In that case, if the varibable being returned to is not const, then it
uses the non-const version?

No, that's not how it works. You're not overloading on the return type.
The return of const/non-const versions of the same function can be
utterly unrelated, as they are in the code I showed above.

The overload is specifically on whether or not the object who's member
is being accessed is const or not. Generally this is what you want since:

unk k = node.value();

works whether value() returns a reference or value. The important part
is, generally, whether or not the node part itself should be alterable.

--
http://crazycpp.wordpress.com