(j.|.)

[Ray Andrews <rayandrews@eastlink.ca>]

Bart:

Your clipped comments and code:

# ${(j.|.)var} means to join an array with vertical bars; here the var 
is @ for the positional parameters.

# ${~something} means the value of something can be treated as a 
pattern, so the |-joined positional parameters form a pattern.

# "set --" replaces the original positional parameters with this array 
of parameter names.

set -- ${(ok)parameters[(I)${_v_case}${~${(j.|.)@}}]}

... I understand everything but the '(j.|.)' -- it seems ok like this:

     set -- ${(ok)parameters[(I)${_v_case}${~${@}}]}

... I see no vertical bars either before or after.  The PP's print as a 
spaced array either way.  But  you didn't but that in for no reason.  
Besides, the idea of joining the array seems backwards.