Bug with associative array and P flag?

Bug with associative array and P flag?

[Jonathan Hankins]

Hi,

Below are two examples of using the P flag to variable expansion to access an 
array indirectly.  When using a regular array (foo), this works correctly.  
However, when using an associative array in the same way, I get the value of 
the first (alphabetically? randomly?) key (animal) regardless of the key I 
use.  Should the P flag work with the associative array in the same way as it 
does with the regular array?

I have tested with 4.2.0, 4.1.1 and 4.0.9 on Debian GNU/Linux.

% typeset -a foo
% typeset -A bar
%
% foo=(this is an array)
%
% bar[color]=red
% bar[animal]=cat
% bar[fruit]=apple
%
%
% ref=foo
% print ${${(P)ref}[1]}
this
% print ${${(P)ref}[2]}
is
% print ${${(P)ref}[3]}
an
% print ${${(P)ref}[4]}
array
%
% ref=bar
% print ${${(P)ref}[color]}
cat
% print ${${(P)ref}[animal]}
cat
% print ${${(P)ref}[fruit]}
cat
%

Just for kicks, this works as expected:

% print ${${(P)ref}}
cat apple red
% print ${${(Pk)ref}}                                               
animal fruit color
% print ${${(Pkv)ref}}
animal cat fruit apple color red

Thanks,

-Jonathan Hankins

Re: Bug with associative array and P flag?

[Oliver Kiddle]

Jonathan Hankins wrote:

> Below are two examples of using the P flag to variable expansion to access an 
> array indirectly.  When using a regular array (foo), this works correctly.  
> However, when using an associative array in the same way, I get the value of 
> the first (alphabetically? randomly?) key (animal) regardless of the key I 
> use.  Should the P flag work with the associative array in the same way as it 
> does with the regular array?

This isn't so much a bug as a design limitation. It has nothing in
particular to do with the P flag. Note that:
  print ${${bar}[color]}
would print `cat' just like ${${(P)ref}[color]}

Note also:
  % print $bar
  cat apple red

What is happening is that the inner expansion is returning this as an
array of three items. Using [color] as an index is then equivalent to
using [0] because it is taken as a regular array index and hence a math
expression. Note the difference if you assign color=2 first. Ideally,
we would need an explicit (v) for it to work this way.

For this to work, I think we will need the long overdue major changes
to the parameter code. That's because I don't think the nested
expansion code handles anything other than scalars and arrays for the
nested parameters.

Oliver