Subject: Re: Help me overcome yet another bit of Java/Python brain damage
From: Erik Naggum <>
Date: Fri, 17 May 2002 01:19:37 GMT
Newsgroups: comp.lang.lisp
Message-ID: <>

* Peter Seibel
| Just out of curiosity, how common is it to really use methods that are
| specialized on more than one parameter.

  Any time you have more than one argument to a generic function.  This is
  actually _really_ common.

| I can certainly imagine some circumstances where it would be quite nice
| but it also seems (to my perhaps single-dispatch-language-damaged brain)
| that specializing on more than one argument frequently could cause a
| combinitorial explosion of methods.

  It is not what things could do that should worry you, but what you
  actually do.  Freedom is not a problem to the responsible programmer.

| Am I missing something or do folks mostly (for some value of 'mostly')
| end up using single-dispatch even though it's possible to use
| multiple-dispatch?

  The dispatch is always on all required arguments.  The only way to have
  have single dispatch is to have only one required argument.  If you think
  that specifying the type of a required argument as t means it is no
  longer part of the dispatch, you are simply in error.
  In a fight against something, the fight has value, victory has none.
  In a fight for something, the fight is a loss, victory merely relief.

  70 percent of American adults do not understand the scientific process.