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Re: NULL vs. ""

2005-05-31 06:57:41

On Tue, 2005-05-31 at 07:21 -0400, Mark E. Mallett wrote:
I think a NULL test of some sort could be useful with variables,
but that's another road that's already been paved...

not sure what that expression means, but the document hasn't been
approved yet, so changes can still happen.

the test introduced with variables is "string", so there is no way to
access the value of a variable except inside a string.  likewise for
setting a variable, you (currently) have to provide a string.  having
"${unset_variable}" extrapolate to a special value rather than a string
is IMO ugly and counter-intuitive.

to support NULL values with variables, I see two alternatives:

        a) a new test which takes a variable _name_ as its argument.  we
        also need a NULL token which can be used with that test and with
        b) a new test to check explicitly for unset values.  a new
        action UNSET which can only set variables to the NULL value.

I don't really like a NULL/UNSET token, it opens to many issues.  I
wouldn't mind adding alternative b) to the spec, though, it may be
useful in some cases.
Kjetil T.

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