On 18/09/2012 21:08, Ben Davis wrote:
On 18/09/2012 15:25, David Piepgrass wrote:
Breadth-first (probably never required):
a/b
a/c
a/1.txt
a/2.txt
a/b/1.txt
a/b/2.txt
a/c/z
a/c/1.txt
a/c/z/1.txt
Defining property: number of /'s increases monotonically. Note how the
deeper you go, the more spread out the children become. It's ALL
children, then ALL grandchildren, then ALL great-grandchildren, etc.
I wouldn't bother implementing breadth-first. It's doubtful that
anyone would want it, surely...?
Actually I prefer breadth-first search when searching the file system.
When I search an entire volume, inevitably the (depth-first) search gets
stuck in a few giant, deep directories like the source code of Mono or
some other cave of source code, you know, something 12 directories deep
with 100,000 files in it. A breadth-first search would be more likely to
find the thing I'm looking for BEFORE going spelunking in these 12-deep
caves.
Fair point. :)
So there is a case for implementing breadth-first iteration (or as
Mehrdad suggests, iterative deepening - it's just a CPU-memory
tradeoff). However, the currently implemented 'breadth' (preorder
depth-first) is probably used a lot, and someone might be relying on its
current behaviour (e.g. to create a tree view). So how do we proceed
without silently breaking existing code? Do we use 'breadthFirst'
instead of 'breadth'? Do we just gulp and change it? Do we rename
'SpanMode' to 'TreeMode' or something?
So maybe we'd have:
enum SpanMode {
shallow,
depthFirstPreorder,
depthFirstPostorder,
breadthFirst;
@deprecated alias depthFirstPostorder depth;
@deprecated alias depthFirstPreorder breadth;
}
Also don't forget the intent conveyed by the current docs:
"depth
Spans the directory depth-first, i.e. the content of any subdirectory is
spanned before that subdirectory itself. Useful e.g. when recursively
deleting files.
breadth
Spans the directory breadth-first, i.e. the content of any subdirectory
is spanned right after that subdirectory itself."
This would need to be rewritten to say something like:
"depthFirstPostorder
Spans the directory depth-first postorder, i.e. the content of any
subdirectory is spanned before that subdirectory itself. Useful e.g.
when recursively deleting files.
depthFirstPreorder
Spans the directory depth-first preorder, i.e. the content of any
subdirectory is spanned right after that subdirectory itself.
breadthFirst
Spans the directory breadth-first, i.e. all children are returned first,
followed by all grandchildren, followed by all great-grandchildren, and
so on. Useful e.g. when searching for a file that is likely not to be
very deep."
I personally won't object if everyone feels comfortable with reusing
'breadth' and changing existing behaviour. I just have a feeling it's
generally considered a bad thing. Otherwise I'm all for shortening the
names (perhaps by just omitting 'First' from the depth ones).
:)
