Replace Filename text by start/end position?

Question

I could do this in php, but I know nothing of applescript. The main function I need is PHP's substr_replace, to rename files in a passed array, by start/end string positions, with passed text.
Basically I'm looking for an applescript function to add to an Automator workflow, that will replace filenames with text, by character position. The applescript function would have 4 parameters, (files:Array, startPosition:int, endPosition:int, replaceWith:String). The first is an array of the files passed by Automator's "Get Selected Files" func, then the starting and ending positions for what is to be replaced, finally followed by the string to replace with.
So something like,
function renameFilenamesByPosition(files, startPos, endPos, replaceWith)
for(i=0;i<count(files);i++)
file = files;
oldName = basename(file);
newName = substr_replace(oldName, replaceWith, startPos, endPos);
rename(oldFilename, newName);
Any help in coming up with an applescript that I can do this, and be inserted into an Automator workflow, is MUCH APPRECIATED!! I often have files with number tags, that I'd like to have removed.

Answer 1

I had a substring handler that converted fairly readily, but I was looking for something more general-purpose to put into an Automator action. Using an action is good for making the interface not quite so ugly, but there is a bit more to do to make sure it is robust enough to take whatever the other actions can throw at it. I finally decided on an action that trimmed an adjustable number of characters from the beginning or end, with an option to add a text variable - something that the existing rename doesn't do.
As for my replacement handler, the main difference is that it uses the normal AppleScript index ranges, and the index items can also be text strings. There is also a bit more code to take care of stuff like negative or swapped indexes (yours definitely doesn't like that). It does work differently than the PHP function, which is probably not what you were looking for.
<pre style="
font-family: Monaco, 'Courier New', Courier, monospace;
font-size: 10px;
margin: 0px;
padding: 5px;
border: 1px solid #000000;
width: 720px; height: 340px;
color: #000000;
background-color: #FFEE80;
overflow: auto;"
title="this text can be pasted into the Script Editor">
on run -- examples
set TheText to "00012-myfile.jpeg"
ReplaceTheText of TheText between 1 thru 6 by ""
-- ReplaceTheText of TheText between "000" thru "-" by ""
-- ReplaceTheText of TheText between 1 thru "-" by "xxxx"
display dialog "\"" & the result & "\""
end run
to ReplaceTheText of SomeText between StartItem thru EndItem by ReplacingText
replaces the text between the specified items with ReplacingText
item searches are from left to right (beginning to end)
if an item is not found, the replacement is from the beginning or end
parameters - SomeText [text]: the text to modify
StartItem [mixed]: the starting item or index (negative number is from the end)
EndItem [mixed]: the ending item or index (negative number is from the end)
ReplacingText [Text]: the replacement text
returns [text]: the modified text, or the original text if error (index out of range, etc)
set SomeText to SomeText as text
set TextCount to (count SomeText)
if class of StartItem is in {integer, real} then
if StartItem is less than 0 then set StartItem to ((TextCount + 1) + StartItem) -- make positive index
if (StartItem is greater than TextCount) or (StartItem is less than 1) then return SomeText -- out of range
else
set StartItem to offset of (StartItem as text) in SomeText
if result is 0 then set StartItem to 1 -- the beginning
end if
if class of EndItem is in {integer, real} then
if EndItem is less than 0 then set EndItem to ((TextCount + 1) + EndItem) -- make positive index
if (EndItem is greater than TextCount) or (EndItem is less than 1) then return SomeText -- out of range
else
get (offset of (EndItem as text) in (text StartItem thru -1 of SomeText))
if result is 0 then
set EndItem to TextCount -- the end
else
set EndItem to StartItem + result + (count EndItem) - 2
end if
end if
if StartItem is greater than EndItem then set {StartItem, EndItem} to {EndItem, StartItem} -- swap
if StartItem is not 1 then
set StartItem to text 1 thru (StartItem - 1) of SomeText
else
set StartItem to ""
end if
if EndItem is not TextCount then
set EndItem to text (EndItem + 1) thru TextCount of SomeText
else
set EndItem to ""
end if
return StartItem & ReplacingText & EndItem
end ReplaceTheText
</pre>