Associative array index.

Associative array index.

[Peter Stephenson]

I'm sure we've had this discussion but the behaviour is still inconsistent.
The lexer and the parameter code disagree over the handling of associative
array indices.

% typeset -A foo
% foo=("'" ouch)
% print $foo['
quote> 

but

% print $foo[']'
ouch

Maybe the lexer can be educated, but doing it this way we are always going
to have problems with any expression with `]' in it, especially since no
form of quoting works in the [...].  I'd prefer to do it the way perl does
it, which is if you want quoting you add it yourself.  The current way of
doing it is supposed to be like a double-quoted string, but it isn't, as
this example shows.  I should offer a prize for anyone able to extract
the value of
  foo=("]" ouch)
by direct indexing.  Indirect indexing using a parameter is OK, although
this can get confused, too.

% print ${nonexistent:-"]"}
]
% print $foo[${nonexistent:-"]"}]
zsh: parse error

which shows how thoroughly horrible it is.

-- 
Peter Stephenson <pws@cambridgesiliconradio.com>
Cambridge Silicon Radio, Unit 300, Science Park, Milton Road,
Cambridge, CB4 0XL, UK                          Tel: +44 (0)1223 392070

Re: Associative array index.

[Bart Schaefer]

On Apr 6,  6:09pm, Peter Stephenson wrote:
} Subject: Associative array index.
}
} I'm sure we've had this discussion but the behaviour is still inconsistent.
} The lexer and the parameter code disagree over the handling of associative
} array indices.

Yes.  This is a known problem, because I didn't change the lexer at all when
I added associative arrays.  So the lexer still parses the stuff inside the
[ ] mostly as if it were a math expression, and the substitution code just
checks in the simplest way possible whether the brackets are balanced.

If we're going to change the lexer for this, we might want to consider
whether to handle ksh associative array assignment syntax:

$ typeset -A foo
$ foo=([a]=x [b]=y [c]=z)

Which is equivalent to zsh-3.1.6+'s

% typeset -A foo
% foo=(a x b y c z)

} I'd prefer to do it the way perl does
} it, which is if you want quoting you add it yourself.  The current way of
} doing it is supposed to be like a double-quoted string, but it isn't, as
} this example shows.

The problem withthe "if you want quoting, you add it yourself" style is
that it conflicts with long-standing array subscripting practice.  Perl
has syntactic differences to distinguish normal and associative arrays;
zsh doesn't (and can't if it is to continue acting something like ksh).

But the "as if double-quoted" style could be made to work better.

} I should offer a prize for anyone able to extract
} the value of
}   foo=("]" ouch)
} by direct indexing.

I don't suppose ${(v)foo[(i)[^ -\\\\^-~]]} counts.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com