Re: Fwd: Custom patterns

[bill@cambridge.apple.com (Bill St. Clair)]

At  9:32 AM 1/4/94 -0500, Mark A. Tapia wrote:
>On Mon Jan  3 13:24:47 1994, Andrew Newell Mickish writes
>in response to Karsten Poecks suggestion of 19 DEC to use
>the variant record for pattern:
>>> (defparameter *my-pattern*
>>>         (make-record :pattern
>>>         :b0 238
>>>         ...
>>>         :b7 119))
>
>> I tried this, but I got the error
>>  > Error: :B0 is not a field of record :PATTERN
>>  >        Valid fields are: (:ARRAY)
>
>> Is the technique above supposed to work?
>The short answer is it is not the MPW standard!
>
>>  It seems reasonable to want to supply the values of the fields when
>>  the record is created, rather than calling %put-byte afterwards.
>>  Does the documentation for the pattern record
>>  on p. 715 imply that this is possible?
>
>It is if you only use the old record definition (included below).

It is possible to supply the field values in MAKE-RECORD even
for the "new" pattern record definition. Note that this is
really just a notational convenience as the MAKE-RECORD macro
expands into a #_NewPtr (or #_NewHandle) call follwed by a bunch
of %PUT-BYTE's.

Note also that you usually want a pattern to be a pointer, not
the default handle. I suggest that you never rely on default
record types, but instead always specify the :storage option
to MAKE-RECORD and use PREF or HREF instead of RREF to access
record slots. Note also that the DEFPARAMETER above will not
work correctly in a saved application. macptrs need to be
reinitialized every time you start up the application. That's
what DEF-LOAD-POINTERS is for.

(defvar *my-pattern*)

(def-load-pointers initialize-*my-pattern* ()
  (setq *my-pattern*
        (make-record (:pattern :storage :pointer)
                     (array 0) 1
                     (array 1) 2
                     (array 2) 4
                     (array 3) 8
                     (array 4) 16
                     (array 5) 32
                     (array 6) 64
                     (array 7) 128)))