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Re: Combining Slider and SetterBar in Manipulate

• To: mathgroup at smc.vnet.net
• Subject: [mg115250] Re: Combining Slider and SetterBar in Manipulate
• From: AES <siegman at stanford.edu>
• Date: Tue, 4 Jan 2011 18:53:35 -0500 (EST)
• References: <if1o6b$p86$1@smc.vnet.net> <ifup6c$cnr$1@smc.vnet.net>

In article <ifup6c$cnr$1 at smc.vnet.net>,
 JohnH <ununquadium113 at yahoo.com> wrote:

> > Also...a bit of unsolicited advice.  Your use of Block is a *bad* idea. 
> > It's
> > always bad to reference Block-scoped or Module-scoped variables declared 
> > outside
> > of a Manipulate or Dynamic from within that Manipulate/Dynamic.  If you're
> > wanting to localize the variable 'someData', then Manipulate offers you an 
> > easy
> > way to do that.  Add someData as a control variable, but no control 
> > appearance.  

John, I haven't followed the earlier part of this thread (and scoping is 
something I try to think about as little as possible!), but could you 
expand on this a little?

As an old Fortran programmer, I think in terms of subroutines.  So, in 
building a Manipulate I want to first define a "subroutine" (that is, a 
Module) which depends on, say, 2 or 3 explicit arguments, plus maybe a 
few global parameters which will have already defined values.  This 
subroutine will then return a numerical value or maybe a graphics object.

Then I want to build a Manipulate in which some or all of the explicit 
arguments are controlled by Controls (others may be explicitly set 
within the Manipulate); call this subroutine (or maybe several such 
subroutines) within the Manipulate; and  Plot or Show the object 
returned by the subroutine, or something that depends closely on it, 
still within the Manipulate. 

I guess the primary objective of this approach is brevity of code within 
the Manipulate, plus just general modularity. Is the above a bad 
approach?  -- especially assuming that the overall notebook containing 
the Manipulate will be relatively brief and self-contained, and one 
needn't worry about side effects after the Manipulate has been used.