Hello!
[older mail]
On Sun, Feb 21, 1999 at 11:47:40PM -0800, Sigbjorn Finne (Intl Vendor) wrote:
> Sven Panne <[EMAIL PROTECTED]> writes:
> ...
> > * hClose on a semi-closed handle fails (4.02 has this bug, too):
> [...]
> But that's not the case here. By the time you get around to doing
> the 'hClose', you've read to the end of the file and the semi-closed
> handle has been closed for you (cf. report.)
That means if you have a program like this:
main = do
h <- openFile ...
c <- hGetContents h
do_something c
hClose h
You can't know whether the hClose is correct or not, except if it's
statically known whether do_something really uses up the whole 'c' or not.
To demonstrate that, I've written a long text file (in fact >1MB Postscript)
into /tmp/f.
Then, I ran this:
import IO
a1 c = putStr c
main = do
h <- openFile "/tmp/f" ReadMode
c <- hGetContents h
a1 c
hClose h
That gave the same failure:
Fail: illegal operation
Action: hClose
Handle: {closed}
Reason: handle is closed
Now, substitute this for a1:
a1 c = putStrLn $ (head . lines) c
and there's no failure.
If that is specified that way, I believe thats a mis-specification.
Regards, Hannah.
