On 2024-02-04 06:43, Mark J. Reed wrote:
>
> That's not qutie what's happening. Arithmetic expressions interpret 
> /all/ variables as numbers, whether the variables are /declared/ as 
> integers or not. If a variable's value doesn't look like a number, it 
> is interpreted as the /name /of another variable, which is then looked 
> up recursively. If it gets to a variable that doesn't exist, the value 
> is taken as 0.
I get that.  $(( abc ..... )) ... abc isn't a number therefore it's the 
name of a variable.  However I did:

% var=abc
... outside any (()) and the conversion happened 'retroactively' so to 
speak.

% var=path; print -- $var
path
... 'path' is just a string, there's no implicit conversion to a 
variable.  Ergo:

%var=abc
... seems to me the same.  Later on abc becomes an integer name, and the 
string is lost
>
> ... it will be converted back to a string that just happens to be all 
> digits. What's the difference? Well, let's continue your example:
>
>     *zsh%* var=abc; let var+=2; echo $var
>     *2*
>     *zsh%* var+=2; echo $var # note: no let
>     *22*
>
Right, I get that too.  A string of digits is still a string.

Anyway it goes back to my original speculation/question that implicit 
promotions/conversions do happen thus a 'demotion' -- in the case of 
that glob expansion -- is something that might at least be contemplated 
even if in fact the idea is unsound.  As for me I think that taking a 
string and then using it as the name of an integer is a bit strange, but 
it is what it is and I won't crash into that problem again.