[REBOL] Re: R: Re: R: Re: switch and datatype
From: rgaither:triad:rr at: 17-Jul-2001 13:04
That sounds great!
I would love to have a copy as I'm sure
many folks would.
Oak Ridge, NC - USA
7/17/2001 11:41:44 AM, "Maxim Olivier-Adlhoch" <[max--ordigraphe--com]> wrote:
>I am not sure I catched this thread correctly (I havent' read the prior
>posts, sorry) but I built an object loader/saver/translator three days
>ago and it does really nice tricks.
>I convert the object into a tag-list of value and data pairs (the values
>being contained in blocks, so as to make the switch word safe to use).
>But the real kicker is that I only save out string, integer and block
>data. Any other datatype is ignored.
>I realized that "switch" does not work on datatypes! values so, I simply
>to-string type? for the switch function to work... as in:
>switch to-string type? :switch-value [
> "integer" [print "integer selected"]
> "string" [print "string selected"]
> "block" [print "block selected"]
>note that the ":" in ":switch-value" is ESSENTIAL! Otherwise, any
>function! values are EVALUATED BEFORE returning.
>My code also detects if the values are empty or null (depending on
>datatype this will be: ""  or 0) and only adds them to the tag pair IF
>they aren't empty. cause when you'll create the empty object... that's
>the value they'll get by default :-)... what's the point in using up
>memory for nothing !?
>then If I want to use any value of the tag-pair, I just do:
>value: switch tag-name
>where an example of the tag list's data (as discussed above) looks like:
> "name" ["john doe"]
> "age" 
> "skills" [["carpenter" "programmer" "writter"]]
>If anyone is interested in the actual code, (I do not have in with me
>:-( I will gladly give-it out. You could add and remove datatypes at
>will, to custom tailor it to your needs. I also plan on adding some
>refinements like /all to force it to supply all tags even if empty (but
>still of appropriate datatype).
>The neat thing is that when storing the object's data using the tag
>system above, you can COMPLETELY change the data structure, remove and
>even add new fields to an object and NOTHING WILL crash. So improving
>one's data and increasing the data in your app isnt too dangerous... as
>the objects grow, the new fields just get empty values (and if you
>ever -remove- data in an object, it STILL stays safe ;-). It will only
>set the tags it recognises in an object and get the tags which actually
>have data. transfering data between irrelevent objects is also easy,
>since you just transfer matching data from one object to another, and
>then (again), only the fields which actually have data (saves space AND
>this system makes it REALLY easy to save and load objects to-from disk.
>Maybe everything I say is common-knowledge, maybe its total alien to
>some of you... I don't know yet... as I'm not yet too sure of the level
>of the people on the list (I know some of you are far More advanced than
>me though... writing proper dialects and stuff like that! (time...
>there's never enough of it)
>I just like helping newbies, And its hard to know how much of these are
>on the list... which is why some of my posts go a little beyond the
>exact thread I reply to.
>> -----Original Message-----
>> From: [rebol-bounce--rebol--com]
>> [mailto:[rebol-bounce--rebol--com]]On Behalf Of
>> Romano Paolo Tenca
>> Sent: Monday, July 16, 2001 8:03 PM
>> To: [rebol-list--rebol--com]
>> Subject: [REBOL] R: Re: R: Re: switch and datatype
>> > Hello Romano!
>> > On 06-Lug-01, you wrote:
>> My answer is a little slow...
>> > RT> tipo: string! switch to-word mold tipo [string! [print
>> > RT> "switched"]]
>> > Is there any reason you can't use:
>> > tipo: 'string!
>> yes: because it is calculated
>> > or
>> > tipo: type?/word value-to-check
>> I did not know this refinement! Thank You. It is the same
>> answer of RT.
>> > Also, notice that:
>> > >> switch string! ["" [print "A-ha!"]]
>> > A-ha!
>> I know: it is the same with Find, Select
>> > Regards,
>> > Gabriele.
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Oak Ridge, NC - USA