[m-dev.] for review: stream I/O

[Fergus Henderson]

On 03-Oct-2000, Michael Day <mcda at students.cs.mu.oz.au> wrote:
> 
> > Well, if you don't know the scope of the stream, I think it should
> > always be possible to write your program in continuation-passing
> > style, so that if necessary all the code between the point where
> > the stream is opened and the end of `main' ends up being inside
> > the scope of the `with_stream'.  This won't necessarily be convenient,
> > but I think it should be possible...
> 
> Is it possible to open and close overlapping streams with with_stream?
>
> eg:
> 
> 	open A
> 	open B
> 	do stuff with A and B
> 	close A
> 	close B

No.  But you can write

	with_stream(pred(A) -->
		with_stream(pred(B) -->
			do stuff with A and B
		)
	)

which is equivalent to

 	open A
 	open B
 	do stuff with A and B
 	close B
 	close A

The order of the closes is not likely to be important, is it?

I guess the more difficult situation is when you have something like

 	open A
 	open B
 	do stuff with A and B
 	close A
	open C
	do stuff with B and C
	close B
	open D
	do stuff with C and D
 	...
	... O(N) steps later ...
	...
	do stuff with X and Y
	close X
	open Z
	do stuff with Y and Z
	close Y
	close Z

In this case, if you use `with_stream', you may have to delay the
close of A by O(N) steps.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3        |     -- the last words of T. S. Garp.
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