Lazy Construction and Conversions

| Lazy Construction and Conversions |

## Lazy C++ Casts

The set of lazy C++ cast template classes and functions provide a way of lazily casting certain type to another during parsing. The lazy C++ templates are (syntactically) used very much like the well known C++ casts:

`

        A *a = static_cast_<A *>(_a_lambda_expression_);

`

These casts parallel the ones in the C++ language. Take note however that the lazy versions have a trailing underscore.

- static_cast_<T>(lambda_expression)
- dynamic_cast_<T>(lambda_expression)
- const_cast_<T>(lambda_expression)
- reinterpret_cast_<T>(lambda_expression)

Acknowledgement: Hartmut Kaiser implemented the lazy casts and constructors based on his original work on Spirit SE "semantic expressions" (the precursor of Phoenix).

## Lazy object construction

A set of lazy constructor template classes and functions provide a way of lazily constructing an object of a type from an arbitrary set of lazy arguments in the form of lambda expressions. The construct_ templates are (syntactically) used very much like the well known C++ casts:

`

        A a = construct_<A>(lambda_arg1, lambda_arg2, ..., lambda_argN);

`

where the given parameters are become the parameters to the contructor of the object of type A. (This implies, that type A is expected to have a constructor with a corresponsing set of parameter types.)

The ultimate maximum number of actual parameters is limited by the preprocessor constant PHOENIX_CONSTRUCT_LIMIT. Note though, that this limit should not be greater than PHOENIX_LIMIT.

Copyright © 2001-2002 Joel de Guzman
Use, modification and distribution is subject to the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)