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From: David Park on 14 Jul 2010 05:35
I would like to have a form of input arguments that contain operational
symbols as well as variables, and especially I would like to use the Span
operation. Here is an example:



foo::usage =

"foo[a, b;;c] will operate on structure a between parts b and c.";

foo[a_, (b_Integer?Positive) ;; (c_Integer?Positive)] := {a, b, c}



foo[a, 2;;3]



{a,2,3}



The problem is that I don't know how to write the first part of the usage
message such that the command completion template will come out with two
variable slots for a and b with a ";;" between. Try using command completion
of foo.



However, I was able to write a routine that creates this type of template.



makeTemplate::usage =

"makeTemplate[splvar, {plvars}][function[args\[Ellipsis]] will make \

a template for function in which splvar is a selected placeholder, \

and the symbols listed in plvars are placeholders.";

makeTemplate[splvar_, plvars_] := Function[expr,

Module[

{spl = SymbolName[splvar], pl, splrule, plrules},

If[Length[plvars] > 0,

pl = SymbolName /@ plvars;

plrules = (# -> TagBox[FrameBox[#], "Placeholder"]) & /@ pl,

plrules = {}];

splrule = spl -> TagBox[FrameBox[spl], "SelectionPlaceholder"];

(MakeBoxes[expr] /. splrule /. plrules) // DisplayForm

], HoldFirst]



makeTemplate[a, {b, c}][foo[a, b ;; c]]



gives the desired template, and I can, for example, use that in an
ActionMenu drop-down paste operation.



I just can't get it into a usage message and normal command completion.



David Park UMLF

djmpark(a)comcast.net

<http://home.comcast.net/~djmpark> http://home.comcast.net/~djmpark/


From: magma on 16 Jul 2010 05:17
I was confronted with a similar problem a couple of months ago, while
developing my package xPrint, a point-and-click interface to the
tensor algebra suite xAct.
You can read more on xPrint here

http://sites.google.com/site/xprintforxact/

I needed to create custom made menu-driven templates for the functions
used to define various geometric objects (manifolds,tensors, covariant
derivatives, ect).
I ended up developing what I called enhanced-template-technology,
which basically recreated the exact look and feel of the normal
templates, but with some extra features and completely programmable
and menu-driven.

Although Mathematica offers the ctrl-shift-K (Make Template) menu facility, to
this functionality there does not seem to correspond any programmable
function, so I had to create the input cell (with the template) from
scratch.

In David's specific case however, this might not be necessary.
Consider this workaround:

foo::usage =
"foo[a, Span[b,c]] will operate on structure a between parts b and \
c.";

foo[a_, (b_Integer?Positive) ;; (c_Integer?Positive)] := {a, b, c}

Now you can achieve the same ";;" effect using the standard template
technology.

If this is not good enough, I suppose one could intercept the ctrl-
shift-K command (or create another one) and insert her/his own special
function, like David's makeTemplate.

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