World: r4wp

I repeat, did you take that correction ?
>> blk: [greater? to-decimal do bind reduce [fact1] obj num1]

yes

It works fine with your data

copy that, it must work:

fact1: 'a/a
num1: 99.0
blk: [greater? to-decimal do bind reduce [fact1] obj num1]
objs: []
o: make object! [a: make object! [a: "100.0"]]
append objs o
o: make object! [a: make object! [a: "99.0"]]
append objs o
foreach obj objs [if equal?  do bind blk 'obj true [print obj/a]]

bloody typo again. sorry steve. yes it does work. its 430am here...

Okay

Where are you from ?

india

How have you discovered  Rebol, If I may ask ?

online! was looking for something light and fast (in dev terms)

rebol is ideal

if i do:

fact1: 'a
o: make object [a: "100.9"]
append objs o
foreach obj objs [if equal?  do bind blk 'obj true [print obj/a]]
** Script Error: Invalid argument: a: "100.0"

wtf!

typo again
>> o: make object! [a: "100.9"]
you need sleeping time

nope. i corrected that and still the same error.


i have data stored in json. i use json.r to convert to rebol objects. 
i want to create a query layer on top of this - which is why the 
expression builder...
the fact1 is an attr of the data object. these can be nested.
how best can i build the expression to retrieve the value i want?

There's no better response than: it can be done.
You just have to correct the bugs as they come.

:)

is the complete error that one ?

** Script Error: Invalid argument: a: "100.0"

** Where: to-decimal
** Near: to decimal! :value

yes

so you are trying to convert to a decimal something not convertible

add a probe, just after to-decimal

hmmm...not that i know of...just using the test data i put in here:

>> probe objs
[make object! [
        a: make object! [
            a: "100.0"
        ]
    ] make object! [
        a: make object! [
            a: "99.0"
        ]
    ] make object! [
        a: "199.0"
    ]]

you are trying to convert an object to a decimal

as long as fact1: 'a/a it works fine.
if fact1: 'a - boom!

because your objects have structures which are not always the same

how do i tackle this?

what is the name of the decimal attribute ?

a


blk: any [greater? to-decimal probe do bind reduce [fact1] obj num1 
| greater? to-decimal do bind obj/:fact1 obj num1]??

Currenlty 'a stands for either an object or a string, you can't be 
that vague.
You must choose a clear name  to identify the decimal attribute

rats!

or you must check in your code when 'a is an object!

and fact1 must be initialized accodingly.
Either with 'a either with 'a/a

question:
an object 'a always has only one property called 'a ?

yes

ok it's simpler then, let me try...

fact1: 'a
get-prop: func [o][either object? o [first next second o][o]]

blk: [greater? to-decimal get-prop do bind reduce [fact1] obj num1]objs: 
[]

another question. 

Why are you using the blk variable instead of coding directly in 
the foreach loop ?
The code would be simpler.

meaning?

This is the same thing without the need of the blk code:

foreach obj objs [
	if num1 < get-prop obj/:fact1 [print obj/a]]
]

much simpler, no need to rebind anything

small mistake, missed the to-decimal.

foreach obj objs [
	if num1 < get-prop to-decimal obj/:fact1 [print obj/a]]
]

arghhh

foreach obj objs [
	if num1 < to-decimal get-prop obj/:fact1 [print obj/a]]
]

Anyway, you see the idea

yes...

much simpler

Is it possible to change the background color of the view led? Or 
are the only states available 'true' and 'false' which are green 
and red? I want different background colors for 'true' and 'false' 
states.

view center-face layout [
	across
	l1: led
	label "State" state: field

	btn "Change led state" [
		either l1/data [
			l1/data: false
			state/text: "False"
		][
			l1/data: true
			l1/data: true
			state/text: "True"
		]
		show [l1 state]
	]
]

caelum, take a look at the style code. the colors are likely embedded 
in it:

>> get in get-style 'led 'colors
== [0.255.0 255.0.0]

Then something like this:

stylize [
	led: led with [colors: [<your colors here>]]
]

should probably be STYLIZE/MASTER, sorry.

you can also do this:

view layout [led with [colors: [<your colors here>]]]

Got it, exactly what I was looking for. Thanks.