how to use variable to substitute class's variable?

[Benjamin Kaplan]

On Thu, Mar 17, 2011 at 3:31 AM, Hans <hansyin at gmail.com> wrote:
> I have things like:
> file1:
> class aaa:
>    def __init__(self):
>        self.variable1='a1'
>        self.variable2='a2'
>        self.varable3='a3'
>
>
> in main proc:
> import file1
> b=file1.aaa()
> c={'variable1':'value1','variable2':'value2','variable3':'value3'}
> for key in c:
>    b.key=c[key]  >>>>>>>>>>>Problem is here!!!
>
> I hope put value1 to b.variable1, value2 to b.variable2 and value3 to
> b.variable3. it does not work.  How can I do it?
>

b.key gets the "key" attribute of b, not the attribute that has the
same name as the variable called key. Otherwise, you'd have to
reference it as b."key" normally. If you want to dynamically set the
variable, you'll have to use the setattr function

setattr(b, key, c[key])

>
> By the way, I know dictionary can bind two variable together, like a 2-
> dimension array.  but, if I need group 3 or more variables together,
> (each group has 3 or more variables)like a 3-dimension(or higher)
> array, Is there an easy way besides "class"?
>

A dictionary does not bind two variables together. A dictionary is a
hash map- it maps keys to values. Each key will map to exactly one
value. If you want to store a list of associated values, use a tuple.
A tuple is an immutable collection of objects (the tuple itself is
immutable, not necessarily the objects in it). It can be indexed just
like a list.
>>> l = [(0,0), (0,1,2,3,4,5,6,7), (0,1,'foo', 5 ,6)]
>>> l[0]
(0, 0)
>>> l[2]
(0, 1, 'foo', 5, 6)
>>> l[2][1]