Prvaluetoobject

Prvaluetoobject is an informal term used in discussions of C++ language semantics to describe the process by which a prvalue expression is used to create or initialize an object. In C++, a prvalue (pure rvalue) represents a value without an associated identity, and it must be materialized into an object when it is used to initialize a variable or to form the right-hand side of an assignment.

In practice, prvalue to object conversion occurs in contexts such as direct or copy initialization, where a prvalue expression provides the value that becomes the newly created object. For example, in int x = 5; or MyClass obj = MyClass(1, 2); the prvalue on the right-hand side participates in constructing the target object. The rules governing this transition are closely tied to the language’s value categories and to how constructors, move semantics, and temporary materialization operate.

Historically, compilers would create a temporary object to materialize a prvalue before it materialized into the target object, which could involve extra copy or move operations. Since C++17, the rules were refined to allow more direct initialization and to enable guaranteed copy elision in many cases, reducing or eliminating intermediate temporaries and making the prvalue-to-object transition more efficient in practice.

The term itself is not a formal keyword or standard term; the standard talks about prvalues, glvalues, xvalues, and the concept of temporary materialization. Nevertheless, prvaluetoobject is a common shorthand for describing how a prvalue yields a concrete object via initialization, construction, or, in modern C++, direct initialization with minimal or no intermediates. It remains a useful mental model for understanding move semantics, return value optimization, and object lifetimes in C++.