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[REBOL] Re: string to object - was: Ask

From: greggirwin:starband at: 28-Sep-2001 10:28

Hi Andrew, << This should do the trick and is a little safer: probe get in get to-word "system" to-word "options"
Yeah! That's what Ammon's function builds, on the fly, from a path. << Safer still is: Words-Objects: reduce [ "System Options" system/options "My unique object" make object! [m: 123] "q" :quit ] Thing: select Words-Objects ask "Please enter the name of an object?"
Very cool! I had thought about this kind of approach but the goal will be to dynamically access any object in the system. That would make this approach rather difficult, wouldn't it? I mean, I'd have to build the block initially, and then I'd have to update it periodically. I can see other places, though, where it will be very useful. For example, I did something similar when I needed to dynamically draw an arrow based on a compass direction: sign: func [value[number! money! time!]] [ if positive? value [return 1] if zero? value [return zero] if negative? value [return -1] ] compass: context [ same: 0x0 S: 0x1 N: 0x-1 E: 1x0 W: -1x0 SE: 1x1 NW: -1x-1 NE: 1x-1 SW: -1x1 ] compass-direction: func [ "Returns the compass direction, as a pair, from point a to point b." a[pair!] "The starting reference point" b[pair!] "The ending reference point" ][ to-pair compose [(sign subtract b/1 a/1) (sign subtract b/2 a/2)] ] ; Hard-coded for 3 points (simple triangles) right now fn-arw: func [color[tuple!] points /local result][ result: make block! 2 append result 'draw append/only result compose [pen (color) fill-pen (color) polygon (points/1) (points/2) (points/3)] return result ] arrows: context [ n: fn-arw black [8x0 3x16 13x16] e: fn-arw black [16x8 0x3 0x13] s: fn-arw black [8x16 3x0 13x0] w: fn-arw black [0x8 16x3 16x13] nw: fn-arw black [0x0 16x8 8x16] ne: fn-arw black [16x0 0x8 8x16] se: fn-arw black [16x16 0x8 8x0] sw: fn-arw black [0x16 8x0 16x8] ] arrow-map: reduce [ compass/same arrows/sw compass/N arrows/n compass/E arrows/e compass/S arrows/s compass/W arrows/w compass/NW arrows/nw compass/NE arrows/ne compass/SE arrows/se compass/SW arrows/sw ] ; Get an arrow definition from a compass direction ; select arrow-map direction get-arrow: func [start[pair!] end[pair!]] [ select arrow-map compass-direction start end ] There are two other blocks, similar to arrows and arrow-map that are used to get the offset for a particular arrow so the point will always fall at a target point rather than rotating around a center point. --Gregg