---
name: "__gnu_pbds::detail::maybe_null_type"
section: "3"
platform: "linux"
package: "gcc"
version: "16.2.1+r23+gd564253eb6c8-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/__gnu_pbds::detail::maybe_null_type"
---

# \_\_gnu\_pbds::detail::maybe\_null\_type(3)

Base class for conditionally defining a static data member.

## NAME

\_\_gnu\_pbds::detail::maybe\_null\_type\< Key, Mapped, \_Alloc, Store\_Hash \> - Base class for conditionally defining a static data member.

## SYNOPSIS

\#include \<types\_traits.hpp\>

Inherited by **\_\_gnu\_pbds::detail::types\_traits\< Key, Mapped, \_Alloc, false \>**, **\_\_gnu\_pbds::detail::types\_traits\< Key, Data, \_Alloc, false \>**, **\_\_gnu\_pbds::detail::value\_type\< Key, Mapped, \_Alloc, false \>**, and **\_\_gnu\_pbds::detail::types\_traits\< Key, Mapped, \_Alloc, Store\_Hash \>**.

## Detailed Description

### template\<typename Key, typename Mapped, typename \_Alloc, bool Store\_Hash\>

struct \_\_gnu\_pbds::detail::maybe\_null\_type\< Key, Mapped, \_Alloc, Store\_Hash \>"Base class for conditionally defining a static data member.

## Author

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