> Marc>   (parameterize ((write-shared #t)
> Marc>                  (write-radix 16)
> Marc>                  (write-prettily #t))
> Marc>     (write X))
>
> Except your old code doesn't know anything about the presence of all
> these flags.  In fact, every new feature controlled via these
> parameters might break the old code.

Could you explain why?  I explicitly said: "But this will not happen
if you code your calls to write in this style: ...", meaning that only
"write" is in the scope of the parameterize.  There is no old code
affected by the parameterize!

Marc