https://www.pistack.xyz/tags/variant/ Recent content in Variant on Pi Stack Hugo en-us Fri, 26 Jun 2026 00:00:00 +0000 https://www.pistack.xyz/posts/2026-06-26-cpp-variant-sum-type-libraries-mpark-tl-expected-boost-variant2/ Fri, 26 Jun 2026 00:00:00 +0000 https://www.pistack.xyz/posts/2026-06-26-cpp-variant-sum-type-libraries-mpark-tl-expected-boost-variant2/ <h2 id="introduction">Introduction</h2> <p>Before <code>std::variant</code> arrived in C++17, representing a value that could be one of several types required either a tagged union (error-prone, no type safety) or inheritance-based polymorphism (heap allocation, virtual dispatch overhead). Even with <code>std::variant</code> available, there are important use cases that the standard library doesn&rsquo;t fully address: backporting to older C++ standards, never-valueless guarantees, and monadic error handling for function return types.</p>