Add parameter to argumentTo()

Author: tomphp

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+### 0.1.6 (2016-01-14)
+
+  * Added: Argument list for `argumentTo($callable, $arguments)`
+
 ### 0.1.5 (2016-01-14)
 
   * Added: `Builder` for prettier object/array traversal.

README.md

@@ -172,7 +172,7 @@ function ($value) {
 
 ### Generic Transformations
 
-#### T\argumentTo(callable $callable)
+#### T\argumentTo(callable $callable, array $argments = [__])
 
 ```php
 T\argumentTo('strtolower');
@@ -184,9 +184,17 @@ function ($value) {
 }
 ```
 
-`$callable` can be any of the following:
+You can also provide a list of arguments using `__` as the placeholder for where
+you want the value inserted:
 
-* `'functionName'`
-* `function ($value) { /* ... */ }`
-* `[$object, 'methodName']`
-* `['ClassName', 'staticMethodName']`
+```php
+use const TomPHP\Transform\__;
+
+T\argumentTo('strpos', ['Tom: My name is Tom', __, 4]);
+
+// Is equivalent to:
+
+function ($value) {
+    return strpos('Tom: My name is Tom', $value, 4);
+}
+```

src/transform.php

@@ -4,6 +4,11 @@
 
 use TomPHP\Transform\Exception\InvalidArgumentException;
 
+/**
+ * Represents a placeholder in an argument list.
+ */
+const __ = 'Super Unique Placeholder String - 6f74f07a-bc60-494a-93e0-eefedb69849b';
+
 /**
  * Chains a number of arity 1 functions together, passing the output of
  * each to the next.
@@ -113,15 +118,23 @@ function getProperty($name)
  * Returns a transformer calls the given callable with its value as the
  * argument and returns the result.
  *
- * @param string|string[] $name Providing an array will walk multiple levels
- *                              into the array.
+ * @param callable $name      Providing an array will walk multiple levels into
+ *                            the array.
+ * @param mixed[]  $arguments Use __ to indicate where the value should be
+ *                            placed in the argument list.
  *
  * @return \Closure
  */
-function argumentTo($callable)
+function argumentTo(callable $callable, array $arguments = [__])
 {
-    return function ($value) use ($callable) {
-        return $callable($value);
+    return function ($value) use ($callable, $arguments) {
+        $arguments = array_map(
+            function ($arg) use ($value) {
+                return $arg === __ ? $value : $arg;
+            },
+            $arguments
+        );
+        return $callable(...$arguments);
     };
 }
 

tests/ArgumentToTest.php

@@ -4,6 +4,7 @@
 
 use PHPUnit_Framework_TestCase;
 use TomPHP\Transform as T;
+use const TomPHP\Transform\__;
 
 final class ArgumentToTest extends PHPUnit_Framework_TestCase
 {
@@ -41,6 +42,14 @@ public function it_calls_a_static_method_with_the_value_as_an_argument_and_retur
         $this->assertSame(3, $fn(4));
     }
 
+    /** @test */
+    public function it_calls_a_function_with_a_positional_argument()
+    {
+        $fn = T\argumentTo('strpos', ['Tom: My name is Tom', __, 4]);
+
+        $this->assertSame(16, $fn('Tom'));
+    }
+
     /**
      * @param int $value
      *