AppleScript for Python Programmers (Comparison Chart)

Written by Aurelio Jargas on July 01, 2005

I'm a Python programmer who switched to Mac OS X. Being nerd and needing to automate common tasks, the learning of the AppleScript language was unavoidable. To speed up the process I've took some notes, comparing the new commands to Python statements. The result is this document.

As the name says, it's intended for Python programmers. But if you're an applescripter interested in Python you may also learn a lot.

Handy functions

The AppleScript language is very limited on data handling. The programmer must build his own tools (functions) to have Python-like functionality to manage strings and lists.

countSubstring()

-- Counts how many times a string appears in a text
-- Note: Its splits the text by the substring and count the items
--
on countSubstring(theText, theSubstring)
 set AppleScript's text item delimiters to theSubstring
 set counter to (count of every text item of theText) - 1
 set AppleScript's text item delimiters to ""
 return counter
end countSubstring

lstripString()

-- Trims the provided string from the text's beginning
--
on lstripString(theText, trimString)
 set x to count trimString
 try
 repeat while theText begins with the trimString
 set theText to characters (x + 1) thru -1 of theText as text
 end repeat
 on error
 return ""
 end try
 return theText
end lstripString

rstripString()

-- Trims the provided string from the text's ending
--
on rstripString(theText, trimString)
 set x to count trimString
 try
 repeat while theText ends with the trimString
 set theText to characters 1 thru -(x + 1) of theText as text
 end repeat
 on error
 return ""
 end try
 return theText
end rstripString

stripString()

-- Trims the provided string from the text's boundaries
-- Note: Requires the lstripString and rstripString functions
--
on stripString(theText, trimString)
 set theText to lstripString(theText, trimString)
 set theText to rstripString(theText, trimString)
 return theText
end stripString

lowerString() / upperString() / capitalizeString()

-- Translate characters of a text
-- Note: Pass the From and To tables as strings (same lenght!)
--
on translateChars(theText, fromChars, toChars)
 set the newText to ""
 if (count fromChars) is not equal to (count toChars) then
 error "translateChars: From/To strings have different lenght"
 end if
 repeat with char in theText
 set newChar to char
 set x to offset of char in the fromChars
 if x is not 0 then set newChar to character x of the toChars
 set newText to newText & newChar
 end repeat
 return the newText
end translateChars
-- Convert a text case to lower characters
-- Note: Requires the translateChars function
--
on lowerString(theText)
 set upper to "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 set lower to "abcdefghijklmnopqrstuvwxyz"
 return translateChars(theText, upper, lower)
end lowerString
-- Convert a text case to upper characters
-- Note: Requires the translateChars function
--
on upperString(theText)
 set lower to "abcdefghijklmnopqrstuvwxyz"
 set upper to "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 return translateChars(theText, lower, upper)
end upperString
-- Capitalize a text, returning only the first letter uppercased
-- Note: Requires translateChars, lowerString and upperString
--
on capitalizeString(theText)
 set firstChar to upperString(first character of theText)
 set otherChars to lowerString(characters 2 thru -1 of theText)
 return firstChar & otherChars
end capitalizeString

replaceString()

-- Replace all occurences of one string for another in a text
-- The trick here is to change the internal delimiter,
-- spliting and joining the text
--
on replaceString(theText, oldString, newString)
 set AppleScript's text item delimiters to oldString
 set tempList to every text item of theText
 set AppleScript's text item delimiters to newString
 set theText to the tempList as string
 set AppleScript's text item delimiters to ""
 return theText
end replaceString

getListItemIndex()

-- Returns the integer index of a list item (zero if not found)
--
on getListItemIndex(theList, theItem)
 repeat with i from 1 to count of theList
 if item i of theList is theItem then return i
 end repeat
 return 0
end getListItemIndex

countListItem()

-- Returns the total count of a specific item in a list
--
on countListItem(theList, theItem)
 set counter to 0
 repeat with i from 1 to count of theList
 if item i of theList is equal to theItem then
 set counter to counter + 1
 end if
 end repeat
 return counter
end countListItem

Thank You Very Much!

This document was reviewed and got valuable contributions from:

• Alfredo Kojima
• André Ruiz
• Osvaldo Santana Neto
• Rudá Moura
• Ryan Wilcox
• Sérgio Bruder

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