Re: [Dr. Geo] DrGWrappedPoint versus Point

[address@hidden]

I was not aware of the hide and show messages, I'll first test that.

So I was not asking to change anything ... but I was just surprised to see that 
the points are actually instances of a class named DrGWrappedPoint 

(this makes sense of course, as it is a layer of DrGeo on top of the basic 
Smalltalk or Cuis Point class).

I'll first test some other examples ...

Regards,
David Stes

----- Op 21 apr 2024 om 12:34 schreef Hilaire Fernandes hfern@free.fr:

> Hi David,
> 
> As you have observed, when creating a segment with the message
> #segment:to:, the argument can be both a Smalltalk point object (5@4) or
> a DrGeo Point instance you will have created with the #point: message
> (figure point: 5@4).
> 
> In the first case, underneath the argument (5@4) is used to create a
> DrGeo point, but because the user did not create the point through
> DrGeo, it is kept hidden. The DrGeo point is implicitly created because
> it's needed in the DrGeo model to create the subsequent segment. Hidding
> the implicit point is a trade-off I did so you can create a lof lines
> without having the implicit point visible, it avoids noise in the sketch
> 
> If you want to make visible an implicit point, you can do it afterward.
> Observe:
> 
> sketch  segment:  0@0  to:  5@5.
> (sktech  point:  5@5)show
> 
> In DrGeo, there is a factory of objects, so when you ask for a new
> object (here point), the factory first check if the object already
> exist. That's why you don't have duplicate point at 5@5 in the example
> above. At the second line, the existing DrGeo point 5@5 is returned,
> then it can be revealed to the user with the #show message.
> 
> This behavior of the implicit point is implemented there:
> 
> DrGeoSketch>>wrappedPoint:  aPointOrWrappedPointItem
> "ensure a wrapped point"
>     ^  aPointOrWrappedPointItem  isPoint
>         ifTrue:  [(self  point:  aPointOrWrappedPointItem)hide]
>         ifFalse:    [aPointOrWrappedPointItem]
> 
> It explains that whenever your a pass a Smalltalk point as argument,
> even it already exists, it will be hidden.
> 
> So if you need to reveal one specific point you can write something like
> that:
> 
> sketch  segment:  0@0  to:  ((sketch  point:  5@5)name:  'A')
> 
> I could add an option to the DrGeoSketch to let this behavior adjusted
> by the user. For example:
> 
> sketch  showImplicitPoint.
> sketch  segment:  0@0  to:  5@5.0
> 
> both implicit points will be visible.
> 
> If you are interested by such a feature, open a ticket.
> 
> Hilaire
> 
> Le 20/04/2024 à 20:33, stes@telenet.be a écrit :
>> AB _ sketch segment: A to: B.
>>
>> to
>>
>>
>> AB _ sketch segment: a to: b.
>>
>> and use Point instances as arguments for the segment:to: message,
>> the labels (names) of the points disappear for me.
>>
>> So is it recommended to always use DrGWrappedPoint instances instead of Point
>> instances ?
> 
> --
> GNU Dr. Geo
> http://gnu.org/s/dr-geo/
> http://gnu-drgeo.blogspot.com/