Re: (j.|.)

[Ray Andrews <rayandrews@eastlink.ca>]

On 2023-01-31 12:19, Roman Perepelitsa wrote:
>
> Do you understand what this does?
>
>      print -r -- ${(ok)parameters[(I)pa*|PA*]}

I'm afraid I don't, never seen anything like it before this.  But I'd 
better find out.  I'm sure I've seen the pipe char. as an operator.  
Alternation, no?  But never in this sort of context. That would make 
sense: this pattern OR that pattern.  Above, obviously lower or upper 
case 'pa'.   Except that I can throw three or more patterns at the 
command so that would require another vertical bar, no? : ... pattern1 | 
pattern2 | pattern3 ... so if it only accepted two patterns I'd say 
that's it for sure, but it takes more than two.

  ... but wait ... the 'j' ... I don't know where to read up on that ... 
is it perhaps saying: 'keep on joining forever'?  Again, I've never seen 
it before, but if that's correct, then that's the answer -- join 
everything.  So then the bar in the string is in fact an operator, as I 
suspected, yes?  Then '(I)' matches anything in the alternation string 
and feeds the correct index # into the machinery there which then grabs 
the appropriate name. Sorta.  Yeah, that's gotta be it.  The tree I was 
barking up, was that somehow the aa|bb|cc ... was being directly 
converted into aa bb cc.  No, the former is a huge alternation.  Yes?  
'j' is the power in this.