Protecting stacks

[Richard Gaskin]

Francis Nugent Dixon wrote:

> Hi from Beautiful Brittany,
>
> Mark wrote :
>
>> and even if it is part of a standalone it isn't too difficult
>> to detach the stack and save it as a stackfile again.
>
> Mark, That intrigued me ! Could you clarify that statement
> a little, or point me to a link which will explain how to
> do this.

Stacks are data, and LC handled both textual and binary data with ease.

When you open a stack from disk, what you "go" to is a blob of binary 
data in memory.

This allows us to also "go" to stacks that have no on-disk copy, such as 
when obtained via HTTP:

   go url "http://www.domain.com/somestack.livecode"

Similarly, you can put a stack into the clipboard and "go" to it:

   copy stack "SomeStack"
   put the clipboardData["objects"] into tStack
   go stack tStack

Taking this further, you can stuff stacks into custom properties:

   put url "binfile:MyDrive/MyStack.livecode" into tData
   set the uStoredStack of btn 1 to tData

And you can use that to recreate the stack file again:

   put the uStoredStack of btn 1 into \
     url "binfile:MyDrive/MyStack.livecode"

You can also clone stacks, and when cloned they have no filename but you 
can set this to save them, useful for making documents:

   clone stack "DocTemplate"
   set the filename of it to "MyDrive/MyStack.livecode"
   save stack it

In addition to the clone command, you can also turn a substack into a 
mainstack by setting its mainstack property to itself, or move a 
substack to become a substack in a different stack file by setting its 
mainstack property to that other stack file.

And as with any other data, you can compress stacks so they use less 
storage space, and can run them through encrypt and decrypt to protect 
them on disk.

Or as Stephen suggested, if you store them in custom props you can 
protect only the parts you need protected (the stack data in the props), 
while leaving the stack containing them in its native format so it's 
easy to work with in the IDE.

There are a great many useful things that can be done with stacks both 
in memory and on disk and everything in between.  And with the 
simplicity and robustness of custom properties, they're often a favorite 
file format of mine for data which would otherwise be cumbersome to parse.

Stack files are specially well-suited for hierarchically ordered data of 
minimal depth, as they load faster in many cases than running an array 
through arrayDecode.

For more on using stack files for storage, see:
<http://lists.runrev.com/pipermail/use-livecode/2002-July/006158.html>

--
  Richard Gaskin
  Fourth World
  LiveCode training and consulting: http://www.fourthworld.com
  Webzine for LiveCode developers: http://www.LiveCodeJournal.com
  Follow me on Twitter:  http://twitter.com/FourthWorldSys