feat: Allow reconfiguration of an existing picomath instance

Keeps track of which operations depend on the configuration and
  invalidates them for lazy reconfiguration when the config changes.

complex/add.js

@@ -13,6 +13,7 @@ export default function create(pmath) {
            }
            if (resolve && Math.abs(sum.im/sum.re) < 1e-10) return sum.re
            return sum
-       }])
+       }],
+    create, pmath) // register ourselves for invalidation and reconfiguration
 }
                          

picomathInstance.js

@@ -12,12 +12,32 @@ export default function picomathInstance (instName, config) {
       } else {
          fn[name] = poortf(name, imps, author, data)
       }
+      /* For PoC, just assume only reason to provide author info
+       * is to be invalidated when config changes
+       */
+      if (author) {
+         if (!fn.configUsers.has(author)) {
+            fn.configUsers.set(author, new Set())
+         }
+         fn.configUsers.get(author).add(name)
+      }
       return fn[name]
    }
 
    Object.defineProperty(fn, 'name', {value: instName})
+   // There is an issue below of possible collision between the following
+   // property names and operation names. Since it would not be too hard to
+   // solve, we won't worry about it in this PoC.
    fn.config = config || { resolveComplex: false } // primitive default for POC
-
+   fn.configUsers = new Map()
+   fn.reconfigure = config => {
+      for (const [author, names] of fn.configUsers.entries()) {
+         for (const name of names) {
+            fn[name].invalidate(author)
+         }
+      }
+      fn.config = config
+   }
    return fn
 }
 

test/custom.js

@@ -46,4 +46,10 @@ describe('Custom instances', () => {
       assert.deepStrictEqual(math.add(math.complex(2,3), math.complex(2,-3)),
          math.complex(4,0))
    })
+
+   it("can be reconfigured", () => {
+      res.reconfigure({resolveComplex: false})
+      assert.deepStrictEqual(math.add(math.complex(2,3), math.complex(2,-3)),
+         math.complex(4,0))
+   })
 })