assigning values in __init__

[Ben Finney]

John Salerno <johnjsal at NOSPAMgmail.com> writes:

> Let's say I'm making a game and I have this base class:
>
> class Character(object):
>
>      def __init__(self, name, stats):
>          self.name = name
>          self.strength = stats[0]
>          self.dexterity = stats[1]
>          self.intelligence = stats[2]
>          self.luck = stats[3]
>
> Is this a good way to assign the values to the different attributes?
> Should 'stats' be a list/tuple (like this), or should I do *stats
> instead?

A tuple is fine, but assumes that there is a logical *sequence* to
these values. If that's true, it should be no problem to assign them as:

    class Character(object):
        def __init__(self, name, stats):
            self.name = name
            (self.strength, self.dexterity,
                self.intelligence, self.luck) = stats

    >>> foo = Character("Foo", (10, 11, 9, 10))
    >>> print foo.name, foo.strength, foo.intelligence
    Foo 10 9

In this case, though, I don't see any value in a specific sequence, so
a mapping looks better to me and gives the caller more flexibility in
how to set it up.

    class Character(object):
        stat_keys = ['strength', 'dexterity', 'intelligence', 'luck']
        def __init__(self, name, stats):
            self.name = name
            self.stats = {}
            for (stat_key, stat_value) in [(k, stats[k])
                    for k in self.stat_keys]:
                setattr(self, stat_key, stat_value)

    >>> foo = Character("Foo", dict(
    ...     dexterity = 11, luck = 10,
    ...     strength = 10, intelligence = 9,
    ... ))
    >>> print foo.name, foo.strength, foo.intelligence
    Foo 10 9

> I'm trying to think ahead to when I might want to add new
> attributes

In which case you almost certainly want a mapping, not a sequence.

> and I want to make sure this doesn't get crazy with individual
> parameters instead of just the one list.

This is one of the many reasons why Python's built-in composite types
are so useful. A group of semantically-related values can be passed as
a single composite value.

-- 
 \     "I hope that after I die, people will say of me: 'That guy sure |
  `\                         owed me a lot of money.'"  -- Jack Handey |
_o__)                                                                  |
Ben Finney