feat: recompute values only when dirty

Author: wesleytodd

index.js

@@ -23,6 +23,10 @@ module.exports = function (opts = {}) {
   let cliInput = null
   let promptInput = {}
 
+  // Only recompute values when changed
+  let isDirty = true
+  let currentState = {}
+
   // Process options
   for (const key of optionKeys) {
     let d = options[key]
@@ -60,10 +64,12 @@ module.exports = function (opts = {}) {
     prompt,
     overrides: (_overrides) => {
       overrides = Object.assign({}, overrides, _overrides)
+      isDirty = true
       return instance
     },
     defaults: (_defaults) => {
       defaults = Object.assign({}, defaults, _defaults)
+      isDirty = true
       return instance
     },
     values
@@ -126,6 +132,7 @@ module.exports = function (opts = {}) {
 
     return (argv) => {
       cliInput = cli.parse(argv)
+      isDirty = true
       return instance
     }
   }
@@ -234,12 +241,20 @@ module.exports = function (opts = {}) {
 
     return async () => {
       promptInput = Object.assign(promptInput, await promptor(prompts))
+      isDirty = true
       return instance
     }
   }
 
   function values (_overrides) {
-    return Object.assign({}, defaults, cliInput, promptInput, overrides, _overrides)
+    if (isDirty) {
+      currentState = Object.assign({}, defaults, cliInput, promptInput, overrides)
+      isDirty = false
+    }
+    if (_overrides) {
+      return Object.assign({}, currentState, _overrides)
+    }
+    return currentState
   }
 
   return instance

test/index.js

@@ -249,4 +249,41 @@ suite(pkg.name, () => {
 
     await opts.prompt(['FooBar'])()
   })
+
+  test('recompute only on dirty state', async () => {
+    const opts = opta({
+      options: {
+        foo: true,
+        bar: true
+      },
+      promptModule: () => {
+        return async (prompts) => {
+          return {
+            bar: 'bar'
+          }
+        }
+      }
+    })
+    const obj1 = opts.values()
+    opts.cli()(['--foo=foo'])
+    const obj2 = opts.values()
+    await opts.prompt()()
+    const obj3 = opts.values()
+    opts.overrides({ baz: 'baz' })
+    const obj4 = opts.values()
+    const obj5 = opts.values()
+
+    assert(obj1 !== obj2)
+    assert(obj2 !== obj3)
+    assert(obj3 !== obj4)
+    assert(obj4 === obj5)
+    assert.deepStrictEqual(obj5, {
+      // yargs adds these top two
+      $0: process.argv[1],
+      _: [],
+      foo: 'foo',
+      bar: 'bar',
+      baz: 'baz'
+    })
+  })
 })