Near Final PEP 247 - API for Cryptographic Hash Functions

[Tim Peters]

[Andrew Kuchling, on
    http://python.sourceforge.net/peps/pep-0247.html
]


    Hash function modules define one function:

    new([string])
    new([key] , [string])

        Create a new hashing object and return it.  You can now feed
        arbitrary strings into the object using its update() method,
        and can ask for the hash value at any time by calling its
        digest() method.

It's unclear whether all modules conforming to this spec must support both
flavors of "new".  The syntax of the second flavor of new() is also unclear;
perhaps

    new(key[, string])

was intended?  I expect I'd like it better if the string argument always
came first, and that hash methods requiring a key require a keyword "key="
argument.

        The 'string' parameter, if supplied, will be immediately
        hashed into the object's starting state; an empty string or
        None.

What about "an empty string or None"?  That clause is dangling there without
apparent purpose.

It would be good to make explicit that

    hasher = module.new(string)

is equivalent to

    hasher = module.new()
    hasher.update(string)

When you flesh out the "an empty string or None" clause, it would also be
good to make explicit that

    hasher = module.new()

is equivalent to

    hasher = module.new("")

and to

    hasher = module.new(None)

Other than that stuff at the start, looks peachy!

hope-it's-ok-to-export-crytographic-pep-discussions-ly y'rs  - tim