Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for an old version of Boost. Click here to view this page for the latest version.
Front Page / Tutorial: Metafunctions and Higher-Order Metaprogramming / Lambda Details / Placeholder Expression Definition

Placeholder Expression Definition

Now that you know just what placeholder means, we can define placeholder expression:


A placeholder expression is either:

  • a placeholder


  • a template specialization with at least one argument that is a placeholder expression.

In other words, a placeholder expression always involves a placeholder.