Info Catalog cl: Variable Bindings cl: Control Structure cl: Blocks and Exits

cl: Conditionals

 
 4.4 Conditionals
 ================
 
 These conditional forms augment Emacs Lisp’s simple ‘if’, ‘and’, ‘or’,
 and ‘cond’ forms.
 
  -- Macro: cl-case keyform clause...
      This macro evaluates KEYFORM, then compares it with the key values
      listed in the various CLAUSEs.  Whichever clause matches the key is
      executed; comparison is done by ‘eql’.  If no clause matches, the
      ‘cl-case’ form returns ‘nil’.  The clauses are of the form
 
           (KEYLIST BODY-FORMS...)
 
      where KEYLIST is a list of key values.  If there is exactly one
      value, and it is not a cons cell or the symbol ‘nil’ or ‘t’, then
      it can be used by itself as a KEYLIST without being enclosed in a
      list.  All key values in the ‘cl-case’ form must be distinct.  The
      final clauses may use ‘t’ in place of a KEYLIST to indicate a
      default clause that should be taken if none of the other clauses
      match.  (The symbol ‘otherwise’ is also recognized in place of ‘t’.
      To make a clause that matches the actual symbol ‘t’, ‘nil’, or
      ‘otherwise’, enclose the symbol in a list.)
 
      For example, this expression reads a keystroke, then does one of
      four things depending on whether it is an ‘a’, a ‘b’, a <RET> or
      ‘C-j’, or anything else.
 
           (cl-case (read-char)
             (?a (do-a-thing))
             (?b (do-b-thing))
             ((?\r ?\n) (do-ret-thing))
             (t (do-other-thing)))
 
  -- Macro: cl-ecase keyform clause...
      This macro is just like ‘cl-case’, except that if the key does not
      match any of the clauses, an error is signaled rather than simply
      returning ‘nil’.
 
  -- Macro: cl-typecase keyform clause...
      This macro is a version of ‘cl-case’ that checks for types rather
      than values.  Each CLAUSE is of the form ‘(TYPE BODY...)’.  
      Type Predicates, for a description of type specifiers.  For
      example,
 
           (cl-typecase x
             (integer (munch-integer x))
             (float (munch-float x))
             (string (munch-integer (string-to-int x)))
             (t (munch-anything x)))
 
      The type specifier ‘t’ matches any type of object; the word
      ‘otherwise’ is also allowed.  To make one clause match any of
      several types, use an ‘(or ...)’ type specifier.
 
  -- Macro: cl-etypecase keyform clause...
      This macro is just like ‘cl-typecase’, except that if the key does
      not match any of the clauses, an error is signaled rather than
      simply returning ‘nil’.
 

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