Yes, that's pretty close. attr is an object with properties, and one
of those, attr.edges, is a nested object with its own nested sub-
objects. All these properties and objects are constructed by evalJson
() and then put in a $H() in a manner very similar to what you just
described. I've copied a sample of the structure below.
I was assuming that putting this whole thing within $A() would make
the individual members (properties and objects) iterable, but perhaps
I'm misunderstanding and instead every property and sub-object must be
iterable (that is, understand the [] operator and have a length()
method).
Unfortunately, when the sub-object "edges" is empty, then running each
() on the hash that contains it fails.
arr.each(function(edgeProperty){
// fails if "arr" is an empty Hash. works if "arr" is an empty
Array. fails if "arr" is a filled Array.
Notice that the first "edges" is empty and the second one has one
member: "Brainwriting".
from json:
{
"nodes": {
"Brain Writing ": {
"label": "BRAIN\\nWRITING ",
"height": "0.50",
"width": "0.83",
"fontsize": "10.00",
"fontcolor": "white",
"pos": [
570,
213
],
"id": "1695",
"onmousedown": "startdrag('1695')",
"length": 1,
"edges": [
]
},
"A Perfect Brainstorm ": {
"label": "A PERFECT\\nBRAINSTORM\\n",
"height": "0.50",
"width": "1.11",
"fontsize": "10.00",
"fontcolor": "white",
"pos": [
326,
167
],
"class": "node",
"onmousedown": "startdrag('1701')",
"length": 1,
"edges": {
"Brainwriting ": {
"color": "black",
"penwidth": "0.5",
"fontname": "Arial",
"URL": "javascript:void(predwin(2179))",
"label": "• ",
}
Ron
blog.ideatree.us
On Jul 14, 4:47 pm, Matt Foster <[email protected]> wrote:
> Oh I get it now,
>
> attr.edges isn't an array of edge objects, its just an object with a
> series of properties that define an edge to your shape?
>
> If that is the case and you wish to iterate over the properties and
> execute set on them explicitly, you could do something like...
>
> var arr = $H(attr.edges).keys();
>
> arr.each(function(edgeProperty){
>
> this[edgeProperty].set(...);
>
> }, attr.edges);
>
> On Jul 14, 3:09 pm, ronman <[email protected]> wrote:
>
> > Here's what I'm doing now:
> > $A(attr.edges).each(function(edge) {
> > edge.set(id, new GraphEdge(cv, id, edge));
>
> > }, this);
>
> > Same result. The iterator.length shows zero and the inside of the
> > loop never executes. But the iterator is (correctly, I think) 'Object
> > Brainwriting =Object'
>
> > Just casting around, I also tried taking off the binding to 'this' at
> > the end, doesn't help.
>
> > As before, I'm not getting why anything whatsoever that's in an array
> > shouldn't automatically return length > 0.
>
> > On Jul 14, 1:47 pm, Matt Foster <[email protected]> wrote:
>
> > > > $A(attr.edges).each(function(edge) {
> > > > this.edge.set(id, new GraphEdge(cv, id, edge));
> > > > }, this);
>
> > > edge is your variable, why bother trying to set function ownership?
> > > The function is sent the parameter it needs to act upon. Just remove
> > > "this" from your "this.edge..." line and you should be good.
>
> > > --
>
> > >http://positionabsolute.net
>
> > > On Jul 14, 2:28 pm, ronman <[email protected]> wrote:
>
> > > > This is a newbie question, but I learn a lot every time I ask.
>
> > > > Why do some objects return a zero length?
>
> > > > I'm doing Array.each. In the array at this particular time is a
> > > > single object. Firebug describes that object as
>
> > > > Object Brainwriting color=black penwidth=0.5 fontname=Arial
>
> > > > and I iterate through the array this way:
> > > > $A(attr.edges).each(function(edge) {
> > > > this.edge.set(id, new GraphEdge(cv, id, edge));
> > > > }, this);
>
> > > > But in Prototype's each method the 'edge' iterator (the Brainwriting
> > > > Object), returns zero length:
> > > > function $A(iterable) {
> > > > if (!iterable) return [];
> > > > if (iterable.toArray) return iterable.toArray();
> > > > var length = iterable.length || 0, results = new Array(length);
> > > > // LENGTH NOW IS ZERO
> > > > while (length--) results[length] = iterable[length];
> > > > return results;
>
> > > > }
>
> > > > Maybe the Brainwriting Object is not iterable, but I would expect $A
> > > > (attr.edges) to have made it so before my call to each().
>
> > > > Surely I'm not expected to assign a length attribute to objects myself
> > > > - just lilke 'penwidth' and 'color' were assigned - in order to make
> > > > Array.each() work on objects. Why doesn't the Object.length return
> > > > non-zero when any kind of Object is instantiated?
>
> > > > I'm using Firefox 3.0.10.
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