BLI: add scoped-defer utility to add RAII-like behavior to C types

This utility is useful when using C types that own some resource in
a C++ file. It mainly helps in functions that have multiple return
statements, but also simplifies code by moving construction and
destruction closer together.

Differential Revision: https://developer.blender.org/D14215

1 files changed, 25 insertions, 0 deletions

diff --git a/source/blender/blenlib/tests/BLI_memory_utils_test.cc b/source/blender/blenlib/tests/BLI_memory_utils_test.cc
index 993434ddeba..ab716e5d011 100644
--- a/source/blender/blenlib/tests/BLI_memory_utils_test.cc
+++ b/source/blender/blenlib/tests/BLI_memory_utils_test.cc
@@ -176,4 +176,29 @@ static_assert(!is_same_any_v<int, float, bool>);
 static_assert(!is_same_any_v<int, float>);
 static_assert(!is_same_any_v<int>);
 
+TEST(memory_utils, ScopedDefer1)
+{
+  int a = 0;
+  {
+    BLI_SCOPED_DEFER([&]() { a -= 5; });
+    {
+      BLI_SCOPED_DEFER([&]() { a *= 10; });
+      a = 5;
+    }
+  }
+  EXPECT_EQ(a, 45);
+}
+
+TEST(memory_utils, ScopedDefer2)
+{
+  std::string s;
+  {
+    BLI_SCOPED_DEFER([&]() { s += "A"; });
+    BLI_SCOPED_DEFER([&]() { s += "B"; });
+    BLI_SCOPED_DEFER([&]() { s += "C"; });
+    BLI_SCOPED_DEFER([&]() { s += "D"; });
+  }
+  EXPECT_EQ(s, "DCBA");
+}
+
 }  // namespace blender::tests