Re: why is eval needed?

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

On 2022-11-20 00:55, Stephane Chazelas wrote:


It's the caller's role to pass tree, -L and 1 as separate

> arguments.
Yeah I get it.  The first time I 'got it' was when discussing 'aptitude' 
and the various quotings needed.  Again one is creating an invisible 
level of organization imposed on a string of characters.  Where it got 
confusing was when zsh imposed it's own ideas of grouping, making '-L 2' 
into a single entity.  Dunno if it's really a thing to be desired but 
naively one might like some way of assembling a command string as if it 
was at CLI, that is *just* a string of characters -- which is how I was 
looking at it.
> tree parses its options. It looks like it does not use the
> standard getopt() API or the GNU getopt_long() API for that:
>
> $ nm -D =tree | grep -i getopt
> $ ltrace -e '*opt*@*' tree > /dev/null
> +++ exited (status 0) +++
What are you doing there?  I have no 'nm' command here.  No such command 
in Debian repository.
> So it must be doing it by hand.
Yeah, so much in the GNU/Linux world is ad hoc.  Everybody did their own 
thing.  No rules.
> In any case zsh (or perl) has no saying on how tree may parse
> its options. You have to invoke it the way its meant to be
> invoked and in the case of tree, the option arguments must be
> passed as separate arguments.
Sure.  The main thing is to just understand that.  Not too difficult 
when you do, something might need splitting or joining but it won't take 
long to figure out.  But why does calling 'eval' fix it?  It seems as if 
eval 'flattens' everything -- one is back to a command line string of 
characters with no imposed grouping.
> For most other commands, you would be able to pass them either
> as one -L1 argument or two -L and 1 arguments and also be able
> to combine more than one option in a single argument as in
> -xyL1 (assuming -x and -y are options that don't take
> arguments, are flags/boolean).
Yeah, as I was saying, it does seem that 'tree' is very crabby. Why 
don't the GNU people iron these things out?