1.0.0 added check.then

README.md

@@ -1,4 +1,4 @@
-# check-more-types v0.9.9
+# check-more-types v1.0.0
 
 > Additional type checks for [check-types.js](https://github.com/philbooth/check-types.js)
 
@@ -80,6 +80,8 @@ for advice and examples.
   * [protects optional arguments](#protects-optional-arguments)
   * [check.defend with messages](#checkdefend-with-messages)
   * [check.defend in module pattern](#checkdefend-in-module-pattern)
+* [Safe callback execution](#safe-callback-execution)
+  * [check.then](#checkthen)
 
 
 #### check.defined
@@ -506,6 +508,29 @@ This works great when combined with JavaScript module pattern as in this example
 
 ---
 
+### Safe callback execution
+
+Sometimes we want to execute a function depending on the condition, but without throwing an
+exception. For these cases, there is `check.then`
+
+#### check.then
+
+    function isSum10(a, b) {
+      return a + b === 10;
+    }
+
+    function sum(a, b) {
+      return a + b;
+    }
+    var onlyAddTo10 = check.then(isSum10, sum);
+    // isSum10 returns true for these arguments
+    // then sum is executed
+    onlyAddTo10(3, 7); // 10
+    onlyAddTo10(1, 2); // undefined
+    // sum is never called because isSum10 condition is false
+
+----
+
 ### Small print
 
 Author: Kensho © 2014

bower.json

@@ -1,7 +1,7 @@
 {
   "name": "check-more-types",
   "main": "check-more-types.js",
-  "version": "0.9.9",
+  "version": "1.0.0",
   "homepage": "https://github.com/kensho/check-more-types",
   "license": "MIT",
   "ignore": [

check-more-types.js

@@ -355,7 +355,9 @@
     */
     check.then = function then(condition, fn) {
       return function () {
-        if (condition) {
+        var ok = typeof condition === 'function' ?
+          condition.apply(null, arguments) : condition;
+        if (ok) {
           return fn.apply(null, arguments);
         }
       };

docs/use.md

@@ -420,4 +420,27 @@ This works great when combined with JavaScript module pattern as in this example
     }
     check.raises(callAddWithNonNumbers); // true
 
----
+---
+
+## Safe callback execution
+
+Sometimes we want to execute a function depending on the condition, but without throwing an
+exception. For these cases, there is `check.then`
+
+### check.then
+
+    function isSum10(a, b) {
+      return a + b === 10;
+    }
+
+    function sum(a, b) {
+      return a + b;
+    }
+    var onlyAddTo10 = check.then(isSum10, sum);
+    // isSum10 returns true for these arguments
+    // then sum is executed
+    onlyAddTo10(3, 7); // 10
+    onlyAddTo10(1, 2); // undefined
+    // sum is never called because isSum10 condition is false
+
+----

package.json

@@ -1,7 +1,7 @@
 {
   "name": "check-more-types",
   "description": "Additional type checks for https://github.com/philbooth/check-types.js",
-  "version": "0.9.9",
+  "version": "1.0.0",
   "author": "Gleb Bahmutov <gleb.bahmutov@gmail.com>",
   "bugs": {
     "url": "https://github.com/kensho/check-more-types/issues"

test/unit-tests.js

@@ -18,7 +18,6 @@ describe('check-more-types', function () {
     function doIt() { done = true; }
 
     beforeEach(function () {
-      console.log('done = false');
       done = false;
     });
 
@@ -38,7 +37,51 @@ describe('check-more-types', function () {
     });
 
     it('can evaluate predicate function', function () {
+      function isTrue() { return true; }
+      var safeDo = check.then(isTrue, doIt);
+      safeDo();
+      la(done);
+    });
+
+    it('can evaluate predicate function (returns false)', function () {
+      function isFalse() { return false; }
+      var safeDo = check.then(isFalse, doIt);
+      safeDo();
+      la(!done);
+    });
+
+    it('can evaluate condition based on arguments', function () {
+      function is3(a) {
+        return a === 3;
+      }
+      var safeDo = check.then(is3, doIt);
+      safeDo();
+      la(!done, 'argument was not 3');
+
+      safeDo(3);
+      la(done, 'argument was 3');
+    });
+
+    it('handles multiple arguments', function () {
+      function sumIs10(a, b) { return a + b === 10; }
+      var safeDo = check.then(sumIs10, doIt);
+      safeDo(4, 6);
+      la(done, 'executed');
+      done = false;
+      safeDo(4, 4);
+      la(!done, 'sum was not 10');
+    });
+
+    it('check.then', function () {
+      function isSum10(a, b) { return a + b === 10; }
+      function sum(a, b) { return a + b; }
+      var onlyAddTo10 = check.then(isSum10, sum);
+      // isSum10 returns true for these arguments
+      // then sum is executed
+      la(onlyAddTo10(3, 7) === 10);
 
+      la(onlyAddTo10(1, 2) === undefined);
+      // sum is never called because isSum10 condition is false
     });
   });