sk_at_scope_end

include/private/SkTemplates.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkTemplates_DEFINED
@@ skipping 471 matching lines @@
     /**
      * Returns void* because this object does not initialize the
      * memory. Use placement new for types that require a cons.
      */
     void* get() { return fStorage.get(); }
     const void* get() const { return fStorage.get(); }
 private:
     SkAlignedSStorage<sizeof(T)*N> fStorage;
 };
 
+/**
+ * sk_at_scope_end(stmt) evaluates stmt when the current scope ends.
+ *
+ * E.g.
+ *
+ * int x = 5;
+ * {
+ *    sk_at_scope_end(x--);
+ *    SkASSERT(x == 5);
+ * }
+ * SkASSERT(x == 4);
+ */
+
+template <typename Fn>
+class SkScoped {

[bungeman-skia, 2016/08/24 21:39:49]

As far as naming goes, the current proposal (p0052) seems to lean toward
scope_exit / make_scope_exit. I think the original ScopeGuard class used
AT_SCOPE_EXIT as the name of the define.

+public:
+    SkScoped(Fn&& fn) : fFn(std::move(fn)) {}
+    ~SkScoped() { fFn(); }
+
+private:
+    // It makes no sense to copy SkScoped.
+    SkScoped           (const SkScoped&) = delete;
+    SkScoped& operator=(const SkScoped&) = delete;
+
+    // We could potentially make moving SkScoped work.
+    SkScoped           (SkScoped&&) = delete;
+    SkScoped& operator=(SkScoped&&) = delete;
+
+    Fn fFn;
+};
+
+template <typename Fn>
+static inline SkScoped<Fn> sk_make_scoped(Fn&& fn) { return { std::move(fn) }; }
+
+#define SCOPED_NAMEx(n) scoped_ ## n
+#define SCOPED_NAME(n) SCOPED_NAMEx(n)

[bungeman-skia, 2016/08/24 21:39:49]

These names seem a bit generic for something that will end up in other peoples
translation units. Seems they should be SK_ prefixed, or use
SK_MACRO_APPEND_LINE (or the like) instead.

+
+#define sk_at_scope_end(stmt) \

[bungeman-skia, 2016/08/24 21:39:49]

You evil person making this define look like a function call.

+    SK_UNUSED auto&& SCOPED_NAME(__COUNTER__) = sk_make_scoped([&] { stmt; })

[bungeman-skia, 2016/08/24 21:39:49]

Looks like we've been using SK_MACRO_APPEND_LINE for this sort of thing.
__COUNTER__ is of course cooler than __LINE__, but I don't think there's any
reason SK_MACRO_APPEND_LINE shouldn't use __COUNTER__.

+
 #endif