front script back script

[Rob Cozens]

>  > Does anyone have an example stack of how and why to use a
>  > front/back script?

Hi Tom,

Serendipity Library contains a field, "Keyboard Filter", and a 
handler, sdbKeyboardFilterOn:

on sdbKeyboardFilterOn
   insert the script of field "Keyboard Filter" of card 1 of stack 
"Serendipity_Library.rev" into front
end sdbKeyboardFilterOn

The script of Keyboard Filter traps keyDown & other pertinent 
messages (eg: backSpaceKey, returnInField) before any other Rev 
control, checks to see if the character is legal input for the field 
with focus (eg: it rejects all characters except "0"-"9",<return>, 
<enter>, <backSpace> and (optionally) "-", ".", ",", and/or [currency 
symbol] for fields set up for numeric input), and only passes legal 
input.

The reason this is a frontScript are:

	I want to filter out illegal keystrokes before the character 
is displayed in the field

	I want the filter to trap all keystrokes before any other 
handler has a chance to respond

Hope this helps.
-- 
Rob Cozens, Staff Conservator
Mendonoma Marine Life Conservancy

"Thirty years ago, our fisheries seemed inexhaustible.  Today we know 
they are not.  The fault lies in large measure with man.  Man is a 
voracious consumer, and modern technology has made it possible for 
fishing vessels to harvest the living resources of the seas in 
prodigious amounts."

  -- Eliot L. Richardson, U.S. Secretary of Commerce, 1975
     in "From Abundance to Scarcity" by Michael L. Weber