Introduce a problem poser trait

Elements and regulators use this common interface to write their data
into the constraint problem.

app-proto/src/assembly.rs

@@ -31,6 +31,10 @@ pub type ElementColor = [f32; 3];
 // each assembly has a key that identifies it within the sesssion
 static NEXT_ELEMENT_SERIAL: AtomicU64 = AtomicU64::new(0);
 
+pub trait ProblemPoser {
+    fn pose(&self, problem: &mut ConstraintProblem, elts: &Slab<Element>);
+}
+
 #[derive(Clone, PartialEq)]
 pub struct Element {
     pub id: String,
@@ -123,8 +127,10 @@ impl Element {
             None
         }
     }
-    
+}
-    fn write_to_problem(&self, problem: &mut ConstraintProblem) {
+
+impl ProblemPoser for Element {
+    fn pose(&self, problem: &mut ConstraintProblem, _elts: &Slab<Element>) {
         if let Some(index) = self.column_index {
             problem.gram.push_sym(index, index, 1.0);
             problem.guess.set_column(index, &self.representation.get_clone_untracked());
@@ -134,14 +140,10 @@ impl Element {
     }
 }
 
-pub trait Regulator: OutlineItem {
+pub trait Regulator: ProblemPoser + OutlineItem {
-    // get information
     fn subjects(&self) -> Vec<ElementKey>;
     fn measurement(&self) -> ReadSignal<f64>;
     fn set_point(&self) -> Signal<SpecifiedValue>;
-    
-    // write problem data
-    fn write_to_problem(&self, problem: &mut ConstraintProblem, elts: &Slab<Element>);
 }
 
 pub struct ProductRegulator {
@@ -162,8 +164,10 @@ impl Regulator for ProductRegulator {
     fn set_point(&self) -> Signal<SpecifiedValue> {
         self.set_point
     }
-    
+}
-    fn write_to_problem(&self, problem: &mut ConstraintProblem, elts: &Slab<Element>) {
+
+impl ProblemPoser for ProductRegulator {
+    fn pose(&self, problem: &mut ConstraintProblem, elts: &Slab<Element>) {
         self.set_point.with_untracked(|set_pt| {
             if let Some(val) = set_pt.value {
                 let subject_column_indices = self.subjects.map(
@@ -197,8 +201,10 @@ impl Regulator for HalfCurvatureRegulator {
     fn set_point(&self) -> Signal<SpecifiedValue> {
         self.set_point
     }
-    
+}
-    fn write_to_problem(&self, problem: &mut ConstraintProblem, elts: &Slab<Element>) {
+
+impl ProblemPoser for HalfCurvatureRegulator {
+    fn pose(&self, problem: &mut ConstraintProblem, elts: &Slab<Element>) {
         self.set_point.with_untracked(|set_pt| {
             if let Some(val) = set_pt.value {
                 if let Some(col) = elts[self.subject].column_index {
@@ -441,11 +447,11 @@ impl Assembly {
         let problem = self.elements.with_untracked(|elts| {
             let mut problem_to_be = ConstraintProblem::new(elts.len());
             for (_, elt) in elts {
-                elt.write_to_problem(&mut problem_to_be);
+                elt.pose(&mut problem_to_be, elts);
             }
             self.regulators.with_untracked(|regs| {
                 for (_, reg) in regs {
-                    reg.write_to_problem(&mut problem_to_be, elts);
+                    reg.pose(&mut problem_to_be, elts);
                 }
             });
             problem_to_be
@@ -621,7 +627,7 @@ mod tests {
                 "Sphere".to_string(),
                 [1.0_f32, 1.0_f32, 1.0_f32],
                 engine::sphere(0.0, 0.0, 0.0, 1.0)
-            ).write_to_problem(&mut ConstraintProblem::new(1));
+            ).pose(&mut ConstraintProblem::new(1), &Slab::new());
         });
     }
     
@@ -645,7 +651,7 @@ mod tests {
                 subjects: subjects,
                 measurement: create_memo(|| 0.0),
                 set_point: create_signal(SpecifiedValue::try_from("0.0".to_string()).unwrap())
-            }.write_to_problem(&mut ConstraintProblem::new(2), &elts);
+            }.pose(&mut ConstraintProblem::new(2), &elts);
         });
     }
 }