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## Function make_expr

boost::proto::make_expr — Construct an expression of the requested tag type with a domain and with the specified arguments as children.

## Synopsis

    // In header: <boost/proto/make_expr.hpp>

    template<typename Tag, typename... A>
      typename proto::result_of::make_expr<Tag, A const...>::type const
      make_expr(A const &... a);
    template<typename Tag, typename Domain, typename... A>
      typename proto::result_of::make_expr<Tag, Domain, A const...>::type const
      make_expr(A const &... a);

## Description

This function template may be invoked either with or without specifying a `Domain` template parameter. If no domain is specified, the domain is deduced by examining domains of the given arguments. See ``proto::deduce_domain`` for a full description of the procedure used.

Let ``WRAP`(x)` be defined such that:

- If `x` is a `boost::reference_wrapper<>`, ``WRAP`(x)` is equivalent to ``proto::as_child`<Domain>(x.get())`.

- Otherwise, ``WRAP`(x)` is equivalent to ``proto::as_expr`<Domain>(x)`.

If ``proto::wants_basic_expr`<typename Domain::proto_generator>::value` is true, then let ``E`` be ``proto::basic_expr``; otherwise, let ``E`` be ``proto::expr``.

Let ``MAKE`(Tag, b...)` be defined as ``E`<Tag, `proto::listN`<decltype(b)...> >::make(b...)`.

If `Tag` is ``proto::tag::terminal``, then return ``WRAP`(a0)`.

Otherwise, return `Domain()(`MAKE`(Tag, `WRAP`(a)...))`.