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Variadic Field Validation with Fold Expressions

Medium · template_metaprogramming · Quant Developer interview question · fold-expressions, variadic-templates, c++17, template-metaprogramming, parameter-pack, order-validation

Order validation in a trading system often needs to check multiple numeric fields simultaneously — price, quantity, side multiplier, and risk limits must all satisfy constraints before an order hits the wire. Writing separate checks for each field is brittle and verbose. C++17 fold expressions let you collapse a variadic parameter pack with any binary operator in a single expression: (... && expr) for AND-reduction, (... + expr) for summation, (... expr) for product — all without recursion, hel