stddefaultdeleteT

stddefaultdeleteT is not a term defined in the C++ standard library. It appears to be a misnomer or a shorthand that conflates std::default_delete<T>, the default deleter used by smart pointers, with the idea of an alias such as std::default_delete_t<T> found in some codebases or proposals. The standard library’s own naming is std::default_delete<T> (and a specialized form for arrays, std::default_delete<T[]>).

std::default_delete<T> is a function object used as the default deleter for smart pointers such as std::unique_ptr. It provides an operator() that destroys the owned object by calling delete on the raw pointer. A specialization std::default_delete<T[]> handles deletion of array types using delete[]. This design allows smart pointers to automatically manage resource lifetime without requiring explicit deleter types in common cases.

Some libraries or discussions introduce a type alias named std::default_delete_t<T> to simplify template parameters by equating it with std::default_delete<T>. However, such an alias is not universally guaranteed across all standard library implementations, and portable code should rely on std::default_delete<T> (and its array specialization) rather than assuming a formal std::default_delete_t alias exists in the standard.

In practice, the default deleter is used implicitly by std::unique_ptr unless a custom deleter is supplied. Users may also specify a custom deleter type for specialized destruction needs, enabling custom memory management policies while preserving the overall ownership semantics. See also std::default_delete and std::unique_ptr for related concepts.

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