bug#72952: 30.0.90; Want way to break out of Eshell for loop

bug#72952: 30.0.90; Want way to break out of Eshell for loop

[Sean Whitton]

X-debbugs-cc: jporterbugs@gmail.com

I am trying to run a series of tests like this:

    % for test in tests/tests/tagupl* { tests/using-intree $test }

I want the command to give up as soon as one of the tests fails.  But I
don't think there is any way to break out of the loop?  In POSIX sh, you
could use 'break'.

Thanks.

-- 
Sean Whitton

bug#72952: 30.0.90; Want way to break out of Eshell for loop

[Jim Porter]

On 9/2/2024 1:26 AM, Sean Whitton wrote:
> X-debbugs-cc: jporterbugs@gmail.com
> 
> I am trying to run a series of tests like this:
> 
>      % for test in tests/tests/tagupl* { tests/using-intree $test }
> 
> I want the command to give up as soon as one of the tests fails.  But I
> don't think there is any way to break out of the loop?  In POSIX sh, you
> could use 'break'.

I actually have a patch sitting in my pile of branches that does this, 
but it needs a fair bit more work to get right. The main thing it needs 
is to keep 'break' from bubbling up too far (e.g. if you run an Eshell 
script from inside a loop, 'break' at the top level of the script 
shouldn't break out of the parent loop).

Another way to do something like this would be to embrace the Lispy-ness 
of Eshell and add a command-form for 'throw' and 'catch'. Something like:

   catch my-tag {
     for i in *.el {
      do-stuff
      if something-or-other { throw my-tag }
     }
   }

Or even support both 'throw'/'catch' *and* 'break'...

bug#72952: 30.0.90; Want way to break out of Eshell for loop

[Sean Whitton]

Hello,

On Sun 08 Sep 2024 at 05:59pm -07, Jim Porter wrote:

> On 9/2/2024 1:26 AM, Sean Whitton wrote:
>> X-debbugs-cc: jporterbugs@gmail.com
>> I am trying to run a series of tests like this:
>>      % for test in tests/tests/tagupl* { tests/using-intree $test }
>> I want the command to give up as soon as one of the tests fails.  But I
>> don't think there is any way to break out of the loop?  In POSIX sh, you
>> could use 'break'.
>
> I actually have a patch sitting in my pile of branches that does this, but it
> needs a fair bit more work to get right. The main thing it needs is to keep
> 'break' from bubbling up too far (e.g. if you run an Eshell script from inside
> a loop, 'break' at the top level of the script shouldn't break out of the
> parent loop).
>
> Another way to do something like this would be to embrace the Lispy-ness of
> Eshell and add a command-form for 'throw' and 'catch'. Something like:
>
>   catch my-tag {
>     for i in *.el {
>      do-stuff
>      if something-or-other { throw my-tag }
>     }
>   }
>
> Or even support both 'throw'/'catch' *and* 'break'...

Heh.  throw/catch seems like overkill to me but supporting both would be
cool!

-- 
Sean Whitton