Implement std::any

Implementing type-erased storage with small-object optimization

This hard C++ coding problem tests whether you can build a type-safe, memory-efficient container that holds objects of arbitrary type. It is representative of systems-level interviews at quantitative trading firms, where understanding memory layout, allocation strategy, and C++ metaprogramming all matter.

The core challenge is to balance two competing concerns: storing small types (like integers) directly on the stack to avoid allocation overhead, while delegating larger types to the heap. You must also implement runtime type checking so that retrieving a value as the wrong type triggers an exception, and ensure cleanup happens automatically when the container is destroyed. The strict size budget forces you to think carefully about your data-structure representation.

• Type erasure and runtime type information
• Small-object optimization (SOO) trade-offs
• Memory layout and alignment in C++
• RAII and resource cleanup
• Function pointers or virtual dispatch for type-agnostic operations