@verb #12:"add_feature" this none this rxdo #55
@program #12:"add_feature" this none this
"Add a feature to this player's features list.  Caller must be this or have suitable permissions (this or wizardly)."
"If this is a nonprogrammer, then ask feature if it is feature_ok (that is, if it has a verb :feature_ok which returns a true value, or a property .feature_ok which is true)."
"After adding feature, call feature:feature_add(this)."
"Returns true if successful, E_INVARG if not a valid object, and E_PERM if !feature_ok or if caller doesn't have permission."
if (caller == this || $perm_utils:controls(caller_perms(), this))
  feature = args[1]
  if (typeof(feature) != OBJ || !$recycler:valid(feature))
    return player:tell("That does not even appear to be a valid object.")
  endif
  if (`$code_utils:verb_or_property(feature, "feature_ok", this) ! $failed_match')
    "The object is willing to be a feature."
    if (typeof(this.features) == $LIST)
      "If list, we can simply setadd the feature."
      if (length(args) > 1 && args[2])
        this.features = $list_utils:remove_duplicates({feature, @this.features})
      else
        this.features = setadd(this.features, feature)
      endif
    else
      "If not, we erase the old value and create a new list."
      this.features = {feature}
    endif
    "Tell the feature it's just been added."
    `feature:feature_add(this) ! E_VERBNF => 0'
    return 1
    "We're done."
  else
    return player:tell("You are not permitted to add that feature.")
  endif
else
  raise(E_PERM)
endif
"Last modified by Dax (#789) on Tue May  3 13:45:01 2005 MDT."
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