On 8/7/2025 10:47 PM, Revar Desmera via Discuss wrote:

Yeah, I thought about that, but if there's a need for a "workaround"
then we should just make it work.

I'm not sure when I'de ever actually check how many keys are in an object, except to see if no keys are in the object, in which case I'd just test for !object.
But I don't see why not to support it.

• Revar

On 8/7/2025 11:33 PM, Steve Lelievre via Discuss wrote:

First, you need to define the length of an object.  Revar's definition,
and the one that I would think of would be "the number of elements in
the object", along the same lines as len(vector). I'm not immediately
coming up with a different definition that would be more useful.  (Heck,
I'm not immediately coming up with a different definition that would be
useful at all.)

It's an error.

On 8/8/2025 12:58 AM, Revar Desmera via Discuss wrote:

I'm in pretty much the same boat there, except that it's pretty rare
that I even want to know whether there are no keys.

I created a PR.

https://github.com/openscad/openscad/pull/6080

To me an object’s key count is conceptually different to length so perhaps
instead of monkeying with the behaviour of len to get the key count, a new
built-in function that returns a vector of the keys. Then we could do
things like

echo(len(keys(myObj));

but also process them sequentially

for(i = keys(myObj)) … something …myObj[i];

Kills two birds with one stone.

Steve

On Fri, 8 Aug 2025 at 04:22, Peter Kriens via Discuss <
discuss@lists.openscad.org> wrote:

On 8/8/2025 2:25 AM, Steve Lelievre via Discuss wrote:

I don't entirely disagree, but what else would "length" mean?

Iteration already works directly; if you say "for (k = myObj)" k is set
to each key in sequence.

Your "keys()" is thus

function keys(obj) = [ for (k = obj) k ];

... but that's not really all that interesting.

That's why len( [ for (k = obj) k ] ) works.

Ah okay,

Thanks for teaching me.

Steve

On Fri, 8 Aug 2025 at 08:15, Jordan Brown openscad@jordan.maileater.net
wrote:

Steve Lelievre wrote:

Len() currently returns the number of characters in a string, and the number of top-level elements of a vector:

v = [ 1,2, [3,4] ];
echo( len( v ) ); // ECHO: 3

too easy to do

keys = [ for( o=object( this=”that” ) o ) ]

will make a vector of strings, where the strings are the names of the object’s elements in order of creation

I would like to see a built in member function:

o=object( this=”that” );
k = o.keys();
echo( k ); // ECHO: [“that“]

but then we would also want

ell = o.len()

wouldn’t we?

I would be hesitant to put predefined member functions on objects,
because that intrudes on namespace that the user owns.

(And of course we don't have a $this-like mechanism yet, so this is
premature.)