🚀 go-pugleaf

brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:

> ...
>So: What use can anyone make of a heterogeneous list?

>---Dan

I have written a Smalltalk application which will unload fairly arbitary
recursive objects to an append only Stream (pipe). We use this for
spitting windows and their contents between workstations on a network.
There is no way of knowing the contents of a window structure 
because they are very dynamic.

When I write the structure out to a file I keep a heterogeneous Dictionary
which has as keys each object encountered as the structure is traversed.
The valu in the dictionary at an object is a unique number from a counter.

So, if I find a new object, I increment the counter and store its value
in the dictionary at the new object. Each time I encounter an object in
the traversal I check the dictionary if it is already there I put its
unique integer in the output stream.

When I load a structure from a stream into the curent image I put each object
as I re-create it into a heterogeneous list. It's index in this list
is the unique number assigned in the output dictionary. When I encounter
a reference number on input replace it with inputListAt: anInteger.

While the structure of this text may not be too good. I believe this is 
an application where heterogeneous maniplulation of objects is essential.


Peter Goodall