Implementing stacks in Lingo

 

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Reproduced with permission from Penworks Lingo User"s Journal

-- Source Code from the Lingo User"s Journal -- Copyright (c) 1995 by Penworks Corporation on initStacks   global stackList   set stackList =[:] end initStacks on push whichStack, whatItem   global stackList   set whichList =getaProp(stackList, whichStack)   if (voidP(whichList)) then     set whichList =[]     addProp(stackList, whichStack, whichList)   end if   append(whichList, whatItem) end push on pop whichStack   global stackList   set whichList =getaProp(stackList, whichStack)   if (voidP(whichList)) then     alert "Attempt to pop from non-existent stack: #"&whichStack     return 0   end if   set stackSize =count(whichList)   if not stackSize then     alert "Attempt to pop from empty stack: #"&whichStack     return 0   end if   -- Now get the item, then delete it   set thisItem =getLast(whichList)   deleteAt(whichList, stackSize)   return(thisItem) end pop on closeStacks   global stackList   set stackList =[:] end closeStacks