[racket] returning self as sync result with struct prop:evt and wrap-evt

Matthew Flatt wrote at 06/27/2012 09:31 PM:
>              just read       sync then read
>   direct       45 (gc: 0)      325  (gc: 19)
>   letrec       51 (gc: 0)      834  (gc: 12)
>   self         51 (gc: 0)      1297  (gc: 17)
>    

Thanks for analyzing this, Matthew.  I ended up going with the "letrec" 
approach.

(I'm generally interested in I/O performance, and am fond of "sync" and 
its variants.  My immediate need was to make the "charterm" object in my 
character terminal library a synchronizable event, so that my new 
Rackonsole library could do a "sync" on both the terminal and on the log 
receiver.  I'm happy to report that Racket's very rich events system 
worked great.)

Neil V.