Re: PATCH: internal parameter flags (resend)

[Bart Schaefer <schaefer@brasslantern.com>]

On Dec 14, 10:14am, Peter Stephenson wrote:
} Subject: Re: PATCH: internal parameter flags (resend)
}
} Bart Schaefer wrote:
} > schaefer<506> typeset -Z 5 -T ARY ary
} > schaefer<510> ary=(1 2)
} > schaefer<512> echo $ARY[3]
} > 00002
} > 
} > With PWS's patch applied, $ARY[3] becomes "1" in this example, which
} > I believe is wrong.  (I don't really think 00002 is correct either;
} > in fact I'd have said it should just be "2".  Why should the padding
} > flags of the entire string apply to a slice of it?)
} 
} I agree that the old value is wrong, but I don't see why the new value
} is.  You're now trying to add yet another rule that the padding flags
} are sometimes ignored.

Sorry; no, I'm not; that was just a remark in passing, it has nothing
really to do with the point I was making.  Please ignore it for this
thread.

} > This is distinct from ${${ARY}[3]}, which always was "1".
} > 
} > } % typeset -u param=upper
} > } % UPPER=VALUE
} > } % print ${(P)param}
} > } 
} > } prints nothing, even though $param outputs UPPER, because of the way
} > } flags are handled in the wrong place.
} > 
} > Again I think this was correct as it was.
} 
} I really can't see how. I think it just creates a confusing
} distinction on how parameters are accessed. Why would you set the -u
} flag for a parameter and then expect it not to be applied?  What's
} the point in having both flags on substitution and on parameters
} themselves if the latter only apply at the same time?

I would set it to save me from having to remember to do ${(U)param}
every time I mention $param, regardless of what order the flags are
applied ... but mentioning $param and mentioning ${(P)param} aren't
the same thing.

} > ${(P)param} and ${(P)${param}} should be distinct, because the first
} > uses the value of $param as a name whereas the second treats the
} > substitution of $param as a name.
} 
} To me that's just plain confusing.

Let's consider a parallel situation:  Parameter references in math
expressions.  If I write:

    setopt octalzeroes
    integer -Z5 x=9

Then $(( x )) has the value 9 but $(( $x )) is "bad math expression".
Why wasn't the parameter flag applied to x in the first case?  Do you
think I should have expected it to be?  What if x was not an integer?

So, although I still think that ${(P)param} should use the un-altered
value [*], I'm willing to let the other part of this go because of the
following bad inconsistency with the "old way":

torch% typeset -Z5 x=6
torch% print $#x
5
torch% print $x[4]

torch% 

Either $#x should report the "real" length, or $x[4] should index into
the string whose length was counted.  I suspect that changing $#x in
this case would break a lot more things than changing the subscript.


[*] In part because they're the closest thing we have to namerefs, and
namerefs would not allow these kinds of transformations on the value.