Revise composite success flag handling (#41)

Most of the composite methods return a boolean result indicating whether
or not all of the child handlers successfully performed the operation.
If any of the children fails, the composite result is false.

We were previously using a mix of coding styles:

1. $success = $success && func()
2. $success &= func()
3. if (!func()) { $success = false; }

(1) works fine but results in more (re)writes to $success than are
needed.

(2) is logically equivalent but promotes the value to an integer, which
results in the composite function returning an integer instead of a
boolean. (#40)

(3) is nice because it leaves the $success flag alone until there's a
reason to change it to a failure.

This change updates all of the code to consistently use (3).

Author: jparise

Log/composite.php

@@ -59,7 +59,9 @@ public function open(): bool
         /* Attempt to open each of our children. */
         $this->opened = true;
         foreach ($this->children as $child) {
-            $this->opened = $this->opened && $child->open();
+            if (!$child->open()) {
+                $this->opened = false;
+            }
         }
 
         /* If all children were opened, return success. */
@@ -82,8 +84,8 @@ public function close(): bool
         /* Attempt to close each of our children. */
         $closed = true;
         foreach ($this->children as $child) {
-            if ($child->opened) {
-                $closed = $closed && $child->close();
+            if ($child->opened && !$child->close()) {
+                $closed = false;
             }
         }
 
@@ -107,7 +109,9 @@ public function flush(): bool
         /* Attempt to flush each of our children. */
         $flushed = true;
         foreach ($this->children as $child) {
-            $flushed &= $child->flush();
+            if (!$child->flush()) {
+                $flushed = false;
+            }
         }
 
         /* If all children were flushed, return success. */
@@ -169,7 +173,9 @@ public function log($message, ?int $priority = null): bool
 
             /* If this child has yet to be opened, attempt to do so now. */
             if (!$child->opened) {
-                $success &= $child->open();
+                if (!$child->open()) {
+                    $success = false;
+                }
 
                 /*
                  * If we've successfully opened our first handler, the
@@ -181,8 +187,8 @@ public function log($message, ?int $priority = null): bool
             }
 
             /* Finally, attempt to log the message to the child handler. */
-            if ($child->opened) {
-                $success = $success && $child->log($message, $priority);
+            if ($child->opened && !$child->log($message, $priority)) {
+                $success = false;
             }
         }