According to http://www.lispworks.com/documentation/HyperSpec/Body/11_abab.htm section 19, you can't actually define such methods.
On Thu, Jul 7, 2016 at 1:13 PM, Diogo Franco <diogoalexfra...@gmail.com> wrote: > Hello, > > ecl does not specialize the print-object method on hash-tables: > >> > (find-method #'print-object '() '(hash-table t)) >> Debugger received error of type: SIMPLE-ERROR >> There is no method on the generic function PRINT-OBJECT that agrees on >> qualifiers NIL and specializers (HASH-TABLE T) > > > After reading the hyperspec carefully, I think this is ok, it only requires > it on standard-object and structure-object. However, i still thought that > specializing on hash-table would work, but it doesn't: > >> >> (defmethod print-object ((obj hash-table) stream) (princ "its working" >> >> stream)) >> #<standard-method PRINT-OBJECT (#<The BUILT-IN-CLASS HASH-TABLE> #<The >> BUILT-IN-CLASS T>)> >> >> (make-hash-table) >> #<hash-table 000000000493ee40> > > > Shouldn't we still dispatch the call to this method? And if not, what's the > best way in ecl to customize the printable representation of a hash-table? > > I've tried: >> >> > (set-pprint-dispatch 'hash-table (lambda (s obj) (princ "its working" >> > s))) >> NIL >> > (make-hash-table) >> its working > > > But this sometimes gives an error: >> >> Debugger received error of type: SIMPLE-ERROR >> Tried to modified a read-only pprint dispatch table: >> #<pprint-dispatch-table 0000000003375210> >> Error flushed. > > > Thanks! -- With best regards, Stas.
