[plt-scheme] Catch an unknown method error

On Thu, Feb 21, 2008 at 1:01 PM, Matthias Felleisen
<matthias at ccs.neu.edu> wrote:
>
>  Your macro uses x here to bind the exception. The exp part however
>  comes from your macro user (you for the moment). Just imagine, cruel
>  thought, that the macro user uses the new send macro like this:
>
>   (send x print)
>
>  meaning exp = x. Can you guess what would happen in the world of CL?
>

I understand that but lots of macros I find online use syntax->datum
and stuff like that (I understand it's used for breaking hygiene when
one wants).



On Thu, Feb 21, 2008 at 1:43 PM, Ryan Culpepper <ryanc at ccs.neu.edu> wrote:
>  Catching the exception doesn't tell you whether the immediate 'send'
>  referred to a non-existing method or if the method did exist but some
>  other 'send' failed during the execution of the method.
>
>  Use 'method-in-interface?' and 'object-interface' instead to check the
>  existence of the method before doing the call. Or use
>  'object-method-arity-includes?' again if you also want to forward on
>  arity mismatch.
>
>  Revised code below.
>
>

Haven't thought about that. It's a lot better ;-)

Thanks everyone. I'll be back later ;-)


F