[Newbies] Oponing a file twice

[johnps11 at bigpond.com]

Just as I was thinking I was getting a handle on this I'm terribly
confused...

a _ FileStream fileNamed: 'readme.txt'.

gives me a stream an  the file.

b _ FileStream fileNamed: 'readme.txt'.

gives me nil

a _ nil.
a _ FileStream fileNamed: 'readme.txt'.

a is still nil

It seems that the only way I can reopen this file is to

Smalltalk garbageCollect.

Now if I simply wanted to have two references to the file I could just

b _ a copy.

But what if I open a stream on a file, then reuse my variable, then
sometime later want to use that file again? Do I have to explicitly
perform garbage collection? That seems very wrong.  Do I have to keep a
hold of all references to files and their filenames if I think I _might_
need that file again?  That also seems very wrong.

Scenario:

...
some code
a _ FileStream fileNamed: 'readme.txt'.
some more code
...
a _ result of something
...
even more code
b _ FileStream fileNamed: 'readme.txt'.

I've looked at FileStream, StandardFileStream and MultiByteFileStream for
2 days now and am none the wiser (not quite true, I've learned you can
send Squeak into lala land by putting 'self halt' inside
FileStream>>fileNamed: and then getting any error at all... the debugger
seems to open a stream that opens a debugger that opens a stream that
opens a debugger etc etc)

What am I missing (I assume I'm overlooking something really simple)?

Thanks,

John