Re: Class design with tightly bound iterator

From:
"Jim Langston" <tazmaster@rocketmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 5 Sep 2007 21:11:24 -0700
Message-ID:
<P5LDi.127$TU5.13@newsfe05.lga>
"Barry" <dhb2000@gmail.com> wrote in message news:fbnrjt$1dv$1@aioe.org...

Jim Langston wrote:

"Barry" <dhb2000@gmail.com> wrote in message
news:fbnmo9$m3k$1@aioe.org...

Jim Langston wrote:

someinteratortype it = MyBody("right upper leg");
It should be fairly easy for PartTriangles to return an iterator
pointing to it's std::set for the beginning of the upper leg. However,
it would not actually be in the instance of MyBody, which would have
the set for Torso, but in MyBody's vector of PartTriangles where the
name is "right upper leg". Also is the complication of .end() There
are 5 end()'s, one for head, one for right hand pinky (if I go as far
as fingers), left hand pinkie, right foot, etc..


Well, to iterate YourBody is so hard.

I happened to see an STL-like tree implementation,
it has
in_begin(), in_end()
post_being(), post_end()
...
in pair by the traverse method.

So why not doing so here.


... "in pair by the traverse method..." I'm not familiar with that term,
I'll try to look it up.


Forgive my English,
it like post_order, in_order, pre_order


Hmm.. I looked up the transversal pattern and it seems to be something I'm
doing in another tree type class to serialize it.

void CSkill::Write( std::ostream& os, const std::string& Prefix, const bool
AllowZero, const bool UseExpand ) const
{
    if ( Name_.length() > 0 && ( Value_ > 0 || AllowZero || ! Expand_ ||
Active_ ) )
        os << Prefix << Name_ << "," << Value_ << "," << jml::BoolToStr(
Active_ ) << "," << jml::BoolToStr( Activated_ ) <<
                    "," << jml::BoolToStr( Expand_ ) << std::endl;
    // Only write skills if using expand and expanded, or we're not using
expand
    if ( ! UseExpand || ( UseExpand && Expand_ ) )
    {
        for ( std::map< std::string, CSkill >::const_iterator it =
Skills_.begin(); it != Skills_.end(); ++it )
        {
            (*it).second.Write( os, ( Name_.length() > 0 ? Prefix + Name_ +
"|" : "" ), AllowZero, UseExpand );
        }
    }
}

It looks a little more complicated than it is with all the switches I'm
checking, but basically it's traversing the tree. I don't see how this
really helps me though.

But, yes, it is a form of tree.

As my conceptual idea, I would say why not buy strategy pattern.

begin(Strategy1()), end(Strategy1())


Looking at the strategy design, it seems to be a form of polymorphic
funcion calls. I don't see how that will help me, unless there is some
other form of strategy pattern I'm missing.


Here, I think Design Pattern is just way of communication,
like iterator in STL can also be designed without any virtual functions.
But Strategy here, how to? No experience here, just an idea.

--
Thanks
Barry

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