Problem with Getting info for item (applescript) - applescript

Question

I am a pretty good applescripter, and would like some help with this. I am making a recycle bin application, similar to that of the Windows XP Recycle Bin. It is of course a droplet. When I drop items onto the application, the application starts a subroutine designed to check whether the size limit of the Recycle Bin (Trash) was exceeded. However, when I try to get the info for the items in the Trash, the error message that comes up is: "Finder got an error. File item 1 wasn't found." I really need help :(
The subroutine is below:
on check()
tell application "Finder"
set the total_size to 0
set the trash_items to get every item in trash
if the trash_items is not {} then
repeat with i from 1 to the count of items in trash
set this_info to get info for item i of trash --ERROR ON THIS LINE
set the total_size to the total_size + (size of this_info)
end repeat
try
set the second_value to the free_space / (RBPFMS / 100)
if the total_size is greater than the second_value then
display alert "Size Limit Exceeded" message "The Recycle Bin cannot receive any more items because it can only use " & RBPFMS as string & " of your hard drive." buttons {"OK"} default button 1
return false
else
return true
end if
on error
set RBP to ((path to startup disk) as string) & "Recycle Bin Properties"
display dialog "Error: You have modified the properties file for the Recycle Bin. Do not modify the properties file. It is there to store information that is used to determine the properties for the Recycle Bin." with title "Property File Modified" with icon 0 buttons {"OK"} default button 1
set the name of RBP to "DELETE ME"
error number -128
end try
end if
end tell
end check

Answer 1

The error is caused by the expression info for item i of trash. The subexpression item i of trash returns a (Finder) item object. The info for command however requires an alias or file reference to the file (see AppleScript language guide).
There are two ways to fix the expression. Explicitly cast the item to an alias, i.e.:
repeat with i from 1 to the (count of items) in trash
set this_info to get info for (item i of trash as alias)
set the total_size to the total_size + (size of this_info)
end repeat
Or instead of using the info for command, simply use the Finder item's size property:
repeat with i from 1 to the (count of items) in trash
set the total_size to the total_size + (size of item i)
end repeat
Be sure to have both RBPFMS and free_space declared as global variables in the check function:
on check()
global RBPFMS
global free_space
...
end
Another bug: put parentheses around RBPFMS as string in the display alert statement:
display alert "Size Limit Exceeded" message "The Recycle Bin cannot receive any more items because it can only use " & (RBPFMS as string) & " of your hard drive." buttons {"OK"} default button 1

Answer 2

when I try to call the subroutine, it errors "Can't continue check."
The call needs a "my" in front of "check()".
Telling the Finder to call its "check" subroutine won't work. The Finder will tell you that it doesn't know how to "check". The words it will use are "Finder can't continue check." But you can tell the Finder to call your locally-defined "check" subroutine. You simply prefix my to "check" when you call the subroutine. You need to do this every time you call your own subroutine from inside a tell block.