The current definition in 1.2.2 of what Map(o) does is a harmful dead end. The
current behavior is:
- If o is already a Map then leave it alone.
- Otherwise enumerate the visible properties of o and construct a Map out of
those.
This is harmful because it's guaranteed to cause current and future
incompatibilities. There are many other map-like things for which this is the
wrong default and we'll be unable to fix them for compatibility reasons. Here
are just a few:
- If you construct a Map out of a Vector, you want the mapping of indices to
the elements, with nothing else. The default behavior brings in extraneous
miscellaneous housekeeping properties (length, maybe fixed, perhaps more in the
future).
- Folks will write libraries that define MultiMap and Set classes. We'll want
to later allow natural conversion of these to a Map, but the default will get
in the way.
For these reasons the current definition of Map(o) is broken and should not be
adopted. The fix is to take out the auto-enumerating behavior. If it's
needed, it should be done by a static function.
Waldemar
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