[ALLY] Re: Making dynamic button layouts in VIEW
From: jeff:rebol at: 29-Jan-2001 19:11
Your example is elightening, Bo. I'm usually a little too
lazy of a VID programmer to redo the work that layout does for
me, though, so I generally take a different approach to those
kinds of layouts. Here's an alternative way to do the same:
view layout [
text "Enter names for some buttons divided by spaces"
f: field 200 (go: [
buttons: copy [space 0 style bt button [request/ok face/text]]
foreach item parse f/text none [repend buttons ['bt item]]
view/new layout/origin buttons 0x0
])
button "Show me!" go
]
The above approach can be called "Meta-programming VID" which
means we use REBOL to generate the VID code that we send off
to LAYOUT. You see this meta-programming when we use FOREACH
to add a BT style to the layout we're constructing for each
text peice. In the end we don't have to worry about where
anything's placed or how big the window is because that's what
layout does for us.
Not all VIEW programming problems are amenable to
meta-programming, though. Especially in situations where you
have a layout that you are not going to be re-laying out or
you have moving and changing faces in a layout-- then directly
modifying faces and sizes, offsets and other face facets
becomes very necessary. But if you're just going to create a
single layout out of some random stuff, why not use
metaprogramming?
One other notable difference is instead of reconstructing each
button and directly setting its action function separately, we
just created a STYLE, BT, which takes care of the same action
for all other instances of that style. That's the kind of
thing styles are good at taking care of.
-jeff
