[REBOL] Re: percent! - new datatype request
From: carl:cybercraft at: 11-Jun-2002 20:12
On 11-Jun-02, Joel Neely wrote:
Hi Joel,
Good to have you back.
And see below...
> Carl Read wrote:
>> I think we need it, but not so much because it'd be easier
>> (perhaps) for programming, but because it's more descriptive. For
>> instance, we know what this means...
>> prompt-payment-discount: $5.25
>> but does this...
>> prompt-payment-discount: 5.25
>> mean money or percent?
>> If it was this though...
>> prompt-payment-discount: 5.25%
>> we would know.
> That's what comments (or descriptive names) are for.
> prompt-payment-discount-percent: 5.25
> prompt-payment-discount-factor: 1.0 - (5.25 * 0.01)
> or
> prompt-payment-discount: 0.0525 ;; 5 1/4 percent
Okay, not a good example, so you missed my point. (:
Instead, compare this...
[1.05 12.75 1.15 19.22]
with this...
[%1.05 $12.75 1.15 19.22%]
The datatypes make the data descriptive, both to people and REBOL.
VID's a good example of making use of this, where a number is treated
as width, a pair as width and height, a string as text and so on.
And because they're individual datatypes we don't have to remember a
specific order they need to be in. This doesn't of course work for
all cases as you're often going to need more than one of each
datatype, but it's a very useful feature to have. So instead of
something like this...
button label "A button" width 100 depth 50 color 255.0.0
we can have this...
button "A button" 100x50 255.0.0
I don't think new datatypes should be added willy-nilly, but percent
is definately one that should be there. They wouldn't give it a
button on nearly every calculator if it wasn't in very common use now,
would they?
--
Carl Read
