Mapping, with sequence as key, wildcard and subsequence matching
tjreedy at udel.edu
Thu Jul 16 07:27:36 CEST 2015
On 7/15/2015 9:51 PM, Ben Finney wrote:
> Howdy all,
> What well-defined data type exists with the following properties:
> * Mapping, key → value.
> * Each key is a sequence (e.g. `tuple`) of items such as text strings.
> * Items in a key may be the sentinel `ANY` value, which will match any
> value at that position.
> * A key may specify that it will match *only* sequences of the same
> * A key may specify that it will match sequences with arbitrarily many
> additional unspecified items.
Every key should signal which of the last two alterntives holds. One can
be a default. The signal can be 'in-band', in the tuple key itself, or
'out-of-band', not in the tuple key. An in-band signal must be a
special value, like 'ANY', that is not otherwise used in keys. ...
might be a good choice. For out-of-band, you could try a tuple subclass
with a __new__ method that sets an attribute. Or wrap a tuple, say with
a list, to signal the non-default alternative. Something like
tail = False
if type(key) is list:
tail = True
key = key.pop()
Terry Jan Reedy
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