Add basic promise examples (#179)

examples/promises/deferred.php

@@ -0,0 +1,48 @@
+#!/usr/bin/env php
+<?php
+
+use Amp\Deferred;
+use Amp\Loop;
+
+require_once __DIR__ . "/../../vendor/autoload.php";
+
+/**
+ * @return \Amp\Promise<string>
+ */
+function jobSuccess() {
+    $deferred = new Deferred();
+
+    // We delay Promise resolve for 1 sec to simulate some async job
+    Loop::delay(1 * 1000, function () use ($deferred) {
+        $deferred->resolve("value");
+    });
+
+    return $deferred->promise();
+}
+
+/**
+ * @return \Amp\Promise<string>
+ */
+function jobFail() {
+    $deferred = new Deferred();
+
+    // We delay Promise fail for 2 sec to simulate some async job
+    Loop::delay(2 * 1000, function () use ($deferred) {
+        $deferred->fail(new Exception("force fail"));
+    });
+
+    return $deferred->promise();
+}
+
+Loop::run(function () {
+    try {
+        $asyncOperation1 = yield jobSuccess();
+        echo "asyncOperation1 result -> " . $asyncOperation1 . PHP_EOL;
+
+        // jobFail() will start only after jobSuccess() is finished, all this will be executed asynchronous
+        $asyncOperation2 = yield jobFail();
+        echo "asyncOperation2 result -> " . $asyncOperation2 . PHP_EOL; //this statment will not run
+    } catch (Throwable $exception) {
+        echo "asyncOperation catch -> " . $exception->getMessage() . PHP_EOL;
+    }
+});

examples/promises/onresolve.php

@@ -0,0 +1,56 @@
+#!/usr/bin/env php
+<?php
+
+use Amp\Deferred;
+use Amp\Loop;
+
+require_once __DIR__ . "/../../vendor/autoload.php";
+
+/**
+ * @return \Amp\Promise<string>
+ */
+function jobSuccess() {
+    $deferred = new Deferred();
+
+    // We delay Promise resolve for 1 sec to simulate some async job.
+    Loop::delay(1 * 1000, function () use ($deferred) {
+        $deferred->resolve("value");
+    });
+
+    return $deferred->promise();
+}
+
+/**
+ * @return \Amp\Promise<string>
+ */
+function jobFail() {
+    $deferred = new Deferred();
+
+    // We delay Promise fail for 2 sec to simulate some async job.
+    Loop::delay(2 * 1000, function () use ($deferred) {
+        $deferred->fail(new Exception("force fail"));
+    });
+
+    return $deferred->promise();
+}
+
+// onResolve() shouldn't be used directly in 99% of all cases.
+// Check https://github.com/amphp/amp/issues/178#issuecomment-342460585
+// Check deferred.php for a cleaner code syntax.
+Loop::run(function () {
+    jobSuccess()->onResolve(function (Throwable $error = null, $result = null) {
+        if ($error) {
+            echo "asyncOperation1 fail -> " . $error->getMessage() . PHP_EOL;
+        } else {
+            echo "asyncOperation1 result -> " . $result . PHP_EOL;
+        }
+
+        jobFail()->onResolve(function (Throwable $error = null, $result = null) {
+            if ($error) {
+                echo "asyncOperation2 fail -> " . $error->getMessage() . PHP_EOL;
+            } else {
+                echo "asyncOperation2 result -> " . $result . PHP_EOL;
+            }
+        });
+    });
+});