> How would you go to create an "enum" type in REBOL ?
I haven't needed or missed enums for a long time! :)
I you really need to you could do this:
colours: [
red 1000
green 1100
blue 1300
]
colours/green
;== 1100
But to be honest, I'm trying to think of some reason
I would need to do that. Perhaps if converting C <-> rebol.
> 3) Back on objects:
> objects seem to be pretty neat in REBOL - but I didn't find anything about
> implementing
> and using constructor/destructors ?
>
> I know I could manually add a function that serves as constructor
> each time
> I create an object, but is that the way REBOL requires it ?
Rebol by default, calls no constructor function when it
creates an object using make.
But you can write your own system if you like, really easily:
my-make: func [object spec /local new-obj][
new-obj: make object spec
if in new-obj 'init [new-obj/init] ; do constructor if exists
new-obj ; return the new object
]
Now you can do this (over-simplistic example):
obj: make object! [val: 0 init: does [val: 23]]
probe my-make obj []
> 4) In the same context:
> how do I actually 'free' memory/variables ?
In addition to setting the words to none, you can
unset them:
word: 23
unset 'word
Memory is freed automatically at some later point by the
garbage collector. You can force garbage collection
using recycle:
recycle
> 5) On the webpage about objects one passage mentioned that "sub-objects"
> don't get cloned-
> what does that mean ? Reading that I would expect that all
> objects within an
> object aren't
> available when I create an object on the basis of that object.
> But I seem to be able to use it anyway. Maybe I am getting something wrong
> here ?
My other post about the chickenfarm shows the lack
of cloning, which you probably don't want in the chicken
example. Look at this:
; make an object
measurement: make object! [arm: 23 leg: 34]
; make an object containing a reference to
; the first object
person: make object! [sizes: make measurement []]
; clone the second object
person2: make person []
; check if the "sizes" sub-object is the same in each
same? person/sizes person2/sizes
;== true
Both person and person2 share the same object, well, that means,
currently the 'sizes word points to the one and the same object.
Here's a picture:
person/sizes -----+---> make object! [arm: 23 leg: 34]
|
|
person2/sizes ----'
Let's clone the sub-object now, as well:
person3: make person [sizes: make sizes []]
Here's a picture:
person/sizes ---------> make object! [arm: 23 leg: 34]
person2/sizes --------> make object! [arm: 23 leg: 34]
> 6) in VIEW/VID: How do you open/create several windows simultaneously ?
> I am also talking of being able to refresh each window.
view/new lay: layout [button]
view/new center-face lay2: layout [field]
wait none ; wait for gui events
; (so you can close the windows, otherwise use
;unview/only lay ;, for instance, to close first window)
> 8) On image rotation: is there any simple way to overcome the 90°
> restriction -
> I am not tallking of bitshifting manually ;-)
> What's the reason for this restriction ?
I wish rotation was built in but it hasn't happened yet.
I made a rotation function but it's slow.
http://www.lexicon.net/anton/rebol/library/rotate.r
> 9) Image creation/processing
>
> I read it would be possible to create images on the fly and work
> with these
> then -
> is it possible to store an entire (view) layout within such an image ?
>
> Could you for example draw a line on a "virtual" view and save
> this then to
> an
> image file ?
> Or would you rather simply take the coordinates of the line and create the
> image with that data ?
>
>
> 10) Image processing
>
> Is it possible to create new images (in memory) by adding other images
> to the original image at certain coordinates ?
Yes, line drawing and placing images can be done using the
Rebol/View Draw dialect:
http://www.rebol.com/docs-view.html
> Having tried to overlay transparent GIFs in a VIEW layout, I noticed
> the transparency attribute doesn't seem to be preserved ?
> At least transparent areas of my GIF didn't show the image below that
> one, but rather a WHITE area.
> IF transparent GIFs are supported: what do you need to do to
> really display
> them properly ?
That is a problem of last full release of Rebol/View 1.2.1
A newer beta version will fix it. You can get View 1.2.5 beta here:
http://www.rebol.com/beta-versions.html
or View 1.2.10 beta which is what we are all using anyway:
http://www.reboltech.com/downloads/
(If on windows, download the view1210031.exe)
You can place the executable in the same directory as your
old rebol (just named differently). I have six different
version of rebol/view in the same directory for testing, so it's
safe.
> 11) VID controls
>
> If I need certain additional features for a basic control - like
> a progress
> bar or slider,
> how do I add these ? Do I need to edit the dialect ?
> For example, I want a progress bar with tic-marks as well as a
> non-continous
> filling of the bar.
> So, is there any way to "sub-class" controls easily to enhace their
> functionality/appearance without having to re-write everything
> from scratch?
Yes, there is, but it's a bit advanced, I'm afraid it takes
quite a bit of reading and practise. In the beginning I learned
from Gabriele, Brett Handley www.codeconscious.com and others.
I have also made quite a few styles, see my site
http://www.lexicon.net/anton/rebol/ (better if you go there
via the view desktop.) Go into the gui/ subdirectory and click on
all the links starting with "demo-". Some of them are really
simple, so they can help you learn the basic idea.
> 12) Is there any really thorough information available on ACTIONS
> and EVENTS
> with REBOL/VIEW ?
> They documentation on the REBOL pages seems a bit 'poor' on that matter.
> I don't know yet, how these things are really done behind the scenes.
The ultimate truth can be found in the source, and there's lots
of that. :) There are some quality docs around, not found on the
rebol technologies site.
It was a bit of a struggle to learn the order of events
at first, I admit. Ask your questions here.
> 13) I didn't see any designated function to set pixels at certain
> coordinates in a layout-
> my workaround was using the line word - with 1 width/height.
> How is this really done ?
Unfortunately, that's it. At least it works. :)
> 14) How do I catch mouse events - such as a mouseover event ?
> I read about 'over' - it seems to do exactly what I need - I want
> to display
> controls in a certain area only when the mouse cursor is in that
> said area.
> Also, that functionality could be used to add tooltip-like behaviour to
> buttons
> and menus.
Here's a start:
layout [button feel [probe self]] ; examine button's feel
view layout [
button feel [
over: func [face action event][print 'hello]
]
]
> Mike
Anton.
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