[REBOL] Re: Help
From: emekamicro:gmai:l at: 13-Sep-2010 20:28
Tim,
Thanks so much!
Regards,
Emeka
On Mon, Sep 13, 2010 at 8:06 PM, Tim Johnson <tim-johnsons-web.com> wrote:
> Emeka, I noticed that I introduced some errors into the
> console session that I copied below, so I have removed
> those errors because I am afraid that I may confuse you.
> I.E. disregard my previou email and concentrate on this
> one.
> cheers
> tim
> * Emeka <emekamicro-gmail.com> [100910 02:43]:
> > Tim,
> >
> > Thanks so much!
> >
> > If you won't mind could you throw more light on this:
> > "Also, I recommend that you familiarize yourself with
> > the rebol function interface dialect."
> >
> >
> > I would like to see examples.
> Here's a start:
> Go to http://www.rebol.com/rebolsteps.html
> Do a search on "dialect"
> You should see the following statement:
> """
> You have already seen some simple dialects. For instance, the list
> of arguments to a function is a dialect that can contain many
> variations other than those which have been shown here
> """
> Now go here:
> http://www.rebol.com/docs/core23/rebolcore-9.html
> Look for the link Titled:
> "3.1 Interface Specifications"
> To further edify yourself, write some functions for yourself
> Example:
> >> test: func[a[integer! decimal!]][?? a]
> >> test 1
> a: 1
> == 1
> >> test 2.3
> a: 2.3
> == 2.3
> >> test "abc"
> ** Script Error: test expected a argument of type: integer decimal
> ** Near: test "abc"
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> Now here is the tricky part, but *I* think that it is *very*
> important that you understand this part
> ============================================================
> In rebol a subroutine: of which there are several *and* you can
> "roll your own" - are not compiled into the rebol binary but are
> themselves written in rebol.
> Your can do the follow right from the rebol command line
> ============================================================
> >> source function
> function: func [
> "Defines a user function with local words."
> spec [block!] {Optional help info followed by arg words (and optional
> type and string)}
> vars [block!] "List of words that are local to the function"
> body [block!] "The body block of the function"
> ][
> make function! head insert insert tail copy spec /local vars body
> ]
> >> source func
> func: func [
> "Defines a user function with given spec and body."
> [catch]
> spec [block!] {Help string (opt) followed by arg words (and opt type and
> string)}
> body [block!] "The body block of the function"
> ][
> throw-on-error [make function! spec body]
> ]
> >> source has
> has: func [
> {A shortcut to define a function that has local variables but no
> arguments.}
> locals [block!]
> body [block!]
> ][function [] locals body]
> >> source does
> does: func [
> {A shortcut to define a function that has no arguments or locals.}
> [catch]
> body [block!] "The body block of the function"
> ][
> throw-on-error [make function! [] body]
> ]
> >>
> ============================================================
> In fact, I have written my own rebol subroutine call 'def, which
> like a python def construct, automatically generates local
> variables, and I just about always use 'def for global subroutines.
> HTH
> regards
> tim
>
> >
> > Regards,
> > Emeka
> >
> > On Thu, Sep 9, 2010 at 8:28 PM, Tim Johnson <tim-johnsons-web.com>
> wrote:
> >
> > >
> > > * Emeka <emekamicro-gmail.com> [100909 09:59]:
> > > > Hello All,
> > > >
> > > > I have the below solution, but I want something better.
> > > >
> > > >
> > > > Ismember?: func[my-list start-n n t-element][
> > > > first-element: first at my-list start-n
> > > > if t-element = first-element [return true]
> > > > if start-n = n [return false]
> > > > Ismember? my-list ADD start-n 1 n t-element
> > > > ]
> > > The last line:
> > > > Ismember? my-list ADD start-n 1 n t-element
> > >
> > > would be better coded:
> > > Ismember? my-list (ADD start-n 1) n t-element
> > > for readability, precedence and disclosure of intent.
> > >
> > > Also, I recommend that you familiarize yourself with
> > > the rebol function interface dialect.
> > >
> > > IOWS, you can control the data sent to the function
> > > by specifying the datatypes of the arguments
> > >
> > > Example:
> > > Ismember?: func[my-list[block!] start-n[integer!] n[integer!]
> > > t-element[any-type!]][
> > > ;; .... code here
> > > ]
> > > This approach has at least two advantages:
> > > 1)Clarifies the intent of the function
> > > 2)Generates error messages at the function call rather than
> > > somewhere down the road where some side effect kicks in as
> > > a result of an unintended argument type.
> > >
> > > I hope this helps. If I have confused the issue more, :) I can
> > > elaborate.
> > > tim
> > >
> > > > On Thu, Sep 9, 2010 at 6:38 PM, Emeka <emekamicro-gmail.com> wrote:
> > > >
> > > > >
> > > > > Hello All,
> > > > >
> > > > > Which word would I use for something like this? I have a block [ A
> B C
> > > D] ,
> > > > > I would like to do
> > > > > Ismember? [A B C D] D comes true because D is in the block already
> ,
> > > but
> > > > > Ismember?{A B C D] F comes false.
> > > > >
> > > > >
> > > > > Regards,
> > > > > Emeka
> > > > >
> > > > > --
> > > > > *Satajanus Nig. Ltd
> > > > >
> > > > >
> > > > > *
> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > > *Satajanus Nig. Ltd
> > > >
> > > >
> > > > *
> > > >
> > > >
> > > > --
> > > > To unsubscribe from the list, just send an email to
> > > > lists at rebol.com with unsubscribe as the subject.
> > > >
> > >
> > > --
> > > Tim
> > > tim at johnsons-web.com or akwebsoft.com
> > > http://www.akwebsoft.com
> > > --
> > > To unsubscribe from the list, just send an email to
> > > lists at rebol.com with unsubscribe as the subject.
> > >
> > >
> >
> >
> > --
> > *Satajanus Nig. Ltd
> >
> >
> > *
> >
> >
> > --
> > To unsubscribe from the list, just send an email to
> > lists at rebol.com with unsubscribe as the subject.
> >
>
> --
> Tim
> tim at johnsons-web.com or akwebsoft.com
> http://www.akwebsoft.com
> --
> To unsubscribe from the list, just send an email to
> lists at rebol.com with unsubscribe as the subject.
>
--
*Satajanus Nig. Ltd
*
