Generating Multiple Class Instances

[Julie Torborg]

On Wed, 6 Jun 2001, Paul Prescod wrote:

> 
> There's something funny there. How does each Quark know what its color
> and mass is? What is the definition of getcolor and getmass? 

where getcolor and getflavor are already defined, and you're right, I can
get this part working fine...

> > flavor=['up', 'down', 'strange', 'charm', 'top', 'bottom']
> > for each in flavor:
> >     each=Quark()
> 
> You aren't changing the list. You're just reading from it, never writing
> to it. Here's a straightforward way to do it:

I don't want to change the list, I want to do the same thing as typing 

i_top=Quark(top)
i_bottom=Quark(bottom)

> flavornames = ['up', 'down', 'strange', 'charm', 'top', 'bottom']
> flavors = []
> for each in flavornames:
> 	flavors.append(Quark())
> 
> for each in flavors:
>     print each.color

This just creates a new ordered array.  If I want to access the mass of
top, I still have to know where in the array the top instance lives.  

What I want to do, is starting with my original list, is to make another
list (which is composed of a simple variation on the original list, like
adding the i_ above).  Then if I want to know the mass of charm, I just
type

moc=i_charm.mass

and I don't have to know where anything lives.  

Eventually, all of this will be going into a GUI, and access to all these
parameters will be very non-linear.  The big idea here is to keep all the
"attributes" associated with their "objects."  It seems to be so well
described by the OOP jargon I can't believe I'm having trouble.  What I
visualize is this: 

You've got a whole bunch of balloons (the class) filled with
different gases (the instance). Each has a different color (the "name"), a
string hanging from it and a sticker stuck to it (the attributes). On the
sticker and the string are written words. Now, I set all these balloons
bouncing around.  How do I find what's written on the sticker of the
balloon with helium in it? Well, I have to know what color that balloon 
is, then I can say, "Get the orange balloon."  When the orange balloon 
comes to me, I look at the sticker and say "Eureka."  Now if all the
balloons are the same color, I have to go through all the balloons, or I
have to find another way of "naming" them, like putting them in order on a
line (the ordered list you suggest).  The problem with that is that not
only do I have to know what gas is in what balloon, I have to keep them in
order or I lose that information. 

But, to be fair, the solution you've provided here is better than what
I've come up with.  Maybe there's a way to automatically build a
dictionary that will associate a "name" with each instance.  That still
seems like a lot of keystrokes, not to mention CPU load during lookup
(like I said, there are hundreds of list items, I fictionalized this one
for simplicity), especially when I have a gut feeling that with a little
finesse, there's a much more elegant solution.  Or there should be.