Re: print -D and ${(D)} quoting

[Peter Stephenson <Peter.Stephenson@csr.com>]

On Tue, 12 Oct 2010 18:56:49 -0700
Bart Schaefer <schaefer@brasslantern.com> wrote:
> Is quoting the rest of the string really the correct thing to do?

My contention is that a string of the form "~/with space" is neither nowt
nor something.

> Consider ${${(D)foo}:r} or ${=${(D)foo}}.

${(D)${foo:r}} is the right way round, since the initial $foo is (by
hypothesis) a path understood by the OS, while ${(D)foo} isn't, even
without the quoting.  But why are you doing file operations on a
parameter and then turning it into something that's no longer a file
(or, perhaps better put given what :r is typically used for, that
doesn't allow you to construct a file name you can use in a shell
expression)?

I don't know what ${=${(D)foo}} is supposed to be useful for.

> Why do you believe 
> ${(Q)$(D)foo}} should be necessary to operate on the original
> string, modulo tilde contraction?  Is it because that's easier
> on a zsh script programmer than figuring out where to use (q)?

Yes.  With dynamic directory naming you can have
~[complexexpression]/stuff.  It's valid to have a "/" in the complex
expression.  It's not a simple obvious operation to get a correctly
formatted string even without that.

Under what circumstances do you think it's useful to have a tilde
expression that's not usable as a shell command line argument, anyway?
Surely this can only be cosmetic, in which case having to add (Q) if you
really want a string purely for display is perfectly reasonable?

> Perhaps steps 13 and 14 from the "rules" should be combined in
> some way, so (qD) together differs from either used alone?  

That looks a messier solution to me, though not unworkable given that
you also have the safe option of ~${(q)${(D)...}}.

-- 
Peter Stephenson <pws@csr.com>            Software Engineer
Tel: +44 (0)1223 692070                   Cambridge Silicon Radio Limited
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