Re: [Chicken-hackers] catching compiling exceptions in setup-api

[Felix]

From: Jim Ursetto <address@hidden>
Subject: Re: [Chicken-hackers] catching compiling exceptions in setup-api
Date: Tue, 10 Aug 2010 11:15:12 -0500

> On Tue, Aug 10, 2010 at 02:15, Felix
> <address@hidden> wrote:
>> You can override the ##sys#reset-handler (for example using
>> `parameterize'), which is just a thunk and by default invokes
>> `exit'.
> 
> I thought you might say that.  Is it possible to document that this is
> the official way to catch compilation errors?

It is not the official way, but documenting this might be a good idea.

>  Why does it call
> (reset) instead of (error)?

I can't remember.

>  (execute) calls its arguments in a
> for-each loop, is it safe to escape out of this loop via call/cc from
> the reset handler?

I think it is. That's what continuations are there for, or not?

>  Do I need to worry about the stack?

Which stack?

>  Do I need to
> worry the reset handler might be called due to a real exception?

Yes, since you have overridden it.

> 
> This seems to work to convert the call to reset into an exception,
> does it make sense?
> 
>  (let ((old-reset (##sys#reset-handler)))
>    (parameterize ((##sys#reset-handler
>                    (lambda ()
>                      (parameterize ((##sys#reset-handler old-reset))
>                        (error 'execute "compilation error")))))
>      (compile file.scm)))
> 

Yes. `reset' is there to provide an alternative way of aborting and
throwing into the REPL, if one is active, without printing an
error message. I agree that its use probably doesn't make sense in
`setup-api' and will try to change that.


cheers,
felix