On Sat, 26 Apr 2003 12:21:52 -0400
David Roundy
I had a couple ideas, and I was wondering if they were good ones.
One is the idea of a slice function on an IArray:
a' = slice a (i,j) giving an array with the elements i..j of array a.
[..]
I'm thinking that it may even be possible to make the GC smart enough to get rid of mother strings which are needed by very few children (at least if it's desperate), if array slices were supported at a low enough level... I imagine they'd have to be supported at a very low level.
Perhaps it could be done with cunning use of finalisers. Instead of having the substrings keep references to the 'mother' string, you could reverse it, so the mother keeps (weak?) references to the substrings. That way, when the mother string is garbage collected it can make copies of the substrings in new storage. As you suggest, a further optimisation might be to not collect the mother string if enough of it is still in use. Also when the substrings are copied, you could try and do it in a way that maintains as much sharing as possile if substrings overlap. It porbably still requires significant low-level support by maybe you don't have to teach the garbage collecter specially. Duncan