Document escaping from within code.

[Joel de Guzman]

John:

Just another data point: escaping to BoostBook from within code doesn't work unless the escape is inside a macro:

template <class T> struct function_traits {

static const std::size_t arity = below; typedef below result_type; typedef below arg<replaceable>N</replaceable>_type;

};

Does *not* process the escape, whereas:

[def argN arg<replaceable>N</replaceable>_type] template <class T> struct function_traits {

static const std::size_t arity = below; typedef below result_type; typedef below argN;

};

Does process the escape. Took me a while to figure this out

[Daniel James]

From the ​original email with the formatting corrected:

John:

Just another data point: escaping to BoostBook from within code doesn't work unless the escape is inside a macro:

template <class T>
struct function_traits
{
  static const std::size_t arity = __below;
  typedef __below result_type;
  typedef __below '''arg<replaceable>N</replaceable>_type''';
};

Does not process the escape, whereas:

[def __argN '''arg<replaceable>N</replaceable>_type''']
template <class T>
struct function_traits
{
  static const std::size_t arity = __below;
  typedef __below result_type;
  typedef __below __argN;
};

Does process the escape. Took me a while to figure this out :-(