SYNOPSIS
        mapping m_allocate(int size, int width)

DESCRIPTION
        Reserve memory for a mapping.

        size is the number of entries (i.e. keys) to reserve, width is
        the number of data items per entry. If the optional width is
        omitted, 1 is used as default.

        This is useful only when you are going to construct a mapping
        whose approximate size you know beforehand, to save on malloc
        overhead. If you don't fill in data for all the allocated
        elements, any leftovers will be freed after the current
        function execution ended. It is also useful if you want the
        mapping to have a certain width even if you don't provide
        all the data items for the keys yet.

        If the goal is just to create an empty mapping with a certain
        width, the following notations can be used:

        ([ ]) : creates an empty mapping of width 1.

        ([:width ]) : creates an empty mapping the given <width>, where
            <width> can be any expression yielding an integer result. In
            fact this notation is compiled as 'm_allocate(0, width)' .

EXAMPLES
        m_allocate(3, 7) -> mapping with 7 values per key, and with space
           for 3 entries.

        ([:2*3 ]) -> same as m_allocate(0, 6)

HISTORY
        Renamed from 'allocate_mapping' in LDMud 3.2.6.
        The ([:width ]) notation introduced in LDMud 3.2.9.

SEE ALSO
        mappings(LPC), walk_mapping(E), get_type_info(E), m_reallocate(E)