I am working on rewriting/generalizing a little project which builds
French cleat toolholders, and have a number of questions.  I have a
couple of variants of this using simple cubes, triangles, cylinders,
but I am trying to understand more advanced features of OpenSCAD.

For people that care about such things, French cleats normally come
with a 45 or 30-degree angle, but can be set to any desired angle. 
The choice of materials are often 3/4" plywood, 3/4" lumber (ie 1x*),
1/4" plywood...  Since the angle, thickness, width can all be defined
up front, I would like to set up some reasonable defaults, but allow
the user to override them.

Q1: is there are way to access a nested (sub)module from outside its
parent scope?

I was hoping I could find a way to do something like:

module French_Cleat() {
    module
define_solid_params(thickness=0.75,width=5.5/2,angle=45.0,chamfer=0.0625,saw_kerf=0.125,laseer_kerf=0.06)
    {fc_angle=angle; ...}
function cleat_profile () =....; // uses fc_angle
}

and then be able to call it:

French_Cleat.define_solid_params(angle=30);
cp = French_Cleat.cleat_profile();

That did not work at all...

Q2: it looks like functions are compiled when I include/use a file,
and not when used.  Is there a way around this.

Using the above code, I called:
    define_solid_params(angle=30);
    cp30 = cleat_profile();

and OpenSCAD returned a profile which used the default 45, and not the
overwritten angle=30, because it appears that any global variables are
set at compile time.  Is there a way to work around that?

Sorry for the very basic questions, but I am still learning the syntax
and semantics.

  EBo --

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

Others may have better answers, but I would have define_solid_params()
set global variables like sp_thickness, sp_width, etc.

Jon

On 3/10/2024 5:57 AM, John David via Discuss wrote:

I am working on rewriting/generalizing a little project which builds
French cleat toolholders, and have a number of questions.  I have a
couple of variants of this using simple cubes, triangles, cylinders,
but I am trying to understand more advanced features of OpenSCAD.

For people that care about such things, French cleats normally come
with a 45 or 30-degree angle, but can be set to any desired angle. 
The choice of materials are often 3/4" plywood, 3/4" lumber (ie 1x*),
1/4" plywood...  Since the angle, thickness, width can all be defined
up front, I would like to set up some reasonable defaults, but allow
the user to override them.

Q1: is there are way to access a nested (sub)module from outside its
parent scope?

I was hoping I could find a way to do something like:

module French_Cleat() {
    module
define_solid_params(thickness=0.75,width=5.5/2,angle=45.0,chamfer=0.0625,saw_kerf=0.125,laseer_kerf=0.06)
    {fc_angle=angle; ...}
function cleat_profile () =....; // uses fc_angle
}

and then be able to call it:

French_Cleat.define_solid_params(angle=30);
cp = French_Cleat.cleat_profile();

That did not work at all...

Q2: it looks like functions are compiled when I include/use a file,
and not when used.  Is there a way around this.

Using the above code, I called:
    define_solid_params(angle=30);
    cp30 = cleat_profile();

and OpenSCAD returned a profile which used the default 45, and not
the overwritten angle=30, because it appears that any global
variables are set at compile time.  Is there a way to work around that?

Sorry for the very basic questions, but I am still learning the
syntax and semantics.

  EBo --

---

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

I don't think he wants to use the customizer for these variable, since
they are all inter-related using the formulas in define_solid_params().

Jon

On 3/10/2024 8:49 AM, Raymond West via Discuss wrote:

Yes. Put the user adjustable variables at the front, comment them for
use with the customizer
https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Customizer

On 10/03/2024 12:00, jon via Discuss wrote:

Others may have better answers, but I would have
define_solid_params() set global variables like sp_thickness,
sp_width, etc.

Jon

On 3/10/2024 5:57 AM, John David via Discuss wrote:

I am working on rewriting/generalizing a little project which
builds French cleat toolholders, and have a number of questions.  I
have a couple of variants of this using simple cubes, triangles,
cylinders, but I am trying to understand more advanced features of
OpenSCAD.

For people that care about such things, French cleats normally come
with a 45 or 30-degree angle, but can be set to any desired angle. 
The choice of materials are often 3/4" plywood, 3/4" lumber (ie
1x*), 1/4" plywood...  Since the angle, thickness, width can all be
defined up front, I would like to set up some reasonable defaults,
but allow the user to override them.

Q1: is there are way to access a nested (sub)module from outside
its parent scope?

I was hoping I could find a way to do something like:

module French_Cleat() {
    module
define_solid_params(thickness=0.75,width=5.5/2,angle=45.0,chamfer=0.0625,saw_kerf=0.125,laseer_kerf=0.06)
    {fc_angle=angle; ...}
function cleat_profile () =....; // uses fc_angle
}

and then be able to call it:

French_Cleat.define_solid_params(angle=30);
cp = French_Cleat.cleat_profile();

That did not work at all...

Q2: it looks like functions are compiled when I include/use a file,
and not when used.  Is there a way around this.

Using the above code, I called:
    define_solid_params(angle=30);
    cp30 = cleat_profile();

and OpenSCAD returned a profile which used the default 45, and not
the overwritten angle=30, because it appears that any global
variables are set at compile time.  Is there a way to work around
that?

Sorry for the very basic questions, but I am still learning the
syntax and semantics.

  EBo --

---

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

---

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

Q1: is there are way to access a nested (sub)module from outside its
parent scope?

I was hoping I could find a way to do something like:

module French_Cleat() {
    module
define_solid_params(thickness=0.75,width=5.5/2,angle=45.0,chamfer=0.0625,saw_kerf=0.125,laseer_kerf=0.06)
    {fc_angle=angle; ...}
function cleat_profile () =....; // uses fc_angle
}

Q2: it looks like functions are compiled when I include/use a file,
and not when used.  Is there a way around this.

On 3/10/2024 1:57 AM, John David via Discuss wrote:

Q1: is there are way to access a nested (sub)module from outside its
parent scope?

No.  OpenSCAD modules are black holes.  No information comes out of them.

Also, OpenSCAD variables ... don't vary.  Once set, they cannot be
changed.  (You can create a new instance of a variable in a block, but
that's a new variable and the outer one is unchanged.)

I was hoping I could find a way to do something like:

module French_Cleat() {
module
define_solid_params(thickness=0.75,width=5.5/2,angle=45.0,chamfer=0.0625,saw_kerf=0.125,laseer_kerf=0.06)
{fc_angle=angle; ...}
function cleat_profile () =....; // uses fc_angle
}

Nope.  Can't do anything like that, because there is absolutely no way for
a module to set a global variable.

Q2: it looks like functions are compiled when I include/use a file, and
not when used.  Is there a way around this.

No.  (Though given the scoping rules, it doesn't matter when the file is
"compiled", or that it's compiled at all.)

Advice:

For a simple model where the user wants to set values, put the values
together at the top of the file, so that the user can set them using the
Customizer.  See
https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Customizer for
information on how to add comments to control the labels and other user
interface aspects.

For a subassembly where a program is going to set the values and control
them, the usual strategy is to have your subassembly's module take
parameters, and have the parameters have defaults.

Combining those two concepts:

cube1_size = 10;
cube2_size = 15;
ratio = 2;

twoCubes();
translate([30,0,0]) twoCubes(cube1_size, cube2_size);
translate([60,0,0]) twoCubes(cube1_size * ratio, cube2_size * ratio);

module twoCubes(c1=5, c2=7) {
cube(c1, center=true);
cube(c2);
}

Note that the file has default values (that the user can change with the
customizer) that control the middle pair of cubes, and the module has its
own defaults that control the first pair.

The usual variable scoping is lexical:  you can look at the layout of the
program to see what variables are visible at any given point.  Just walk up
the enclosing blocks until you get to the first variable with that name.

You can use $ variables to pass information into modules or functions.
They are still immutable, but are dynamically scoped.  They are passed down
through calls, no matter how the program is laid out.  Walk up the call
stack until you find the first variable with that name.

$ variables don't lend themselves to module-level defaults, though you can
do it using is_undef().

You can write a variation on the example above as:

$cube1_size = 10;
$cube2_size = 15;

twoCubes();
translate([30,0,0]) {
$cube1_size = 20;
$cube2_size = 30;
twoCubes();
}

module twoCubes() {
cube($cube1_size, center=true);
cube($cube2_size);
}

... but mostly I wouldn't recommend it.

Related notes:

- In any given block, all assignments are processed before all module
invocations.  Don't expect to be able to call a module, then set a $
variable, then call it again.  Both calls will get the value from the
assignment.
- With respect to the model, it almost doesn't matter what order
modules get called in.  (Exceptions:  echo(), rands(), and some cases
involving transparency and coloring that are probably best viewed as
weaknesses in the previewer.)
- The customizer will suck up all constant assignments, until it hits
the first module definition.  If you want to have a global variable that
the user *shouldn't* customize, put in a dummy "module stop();" after the
customizable variables.