[Tutor] Using a string to get at a Variable

[hcohen2]

Isr Gish wrote:

>I'm trying to get the data from a variable using a string.
>For example I have three variables named apples, grapes, pears. Then I have a list with these 3 names as strings.
>Now I would like to do a loop on the list and getsthe data from each name.
>
>Any help would be greatly appreciated.
>
>Thanks in Advance
>
>---------------
>Isr Gish
>
>
>_______________________________________________
>Tutor maillist  -  Tutor at python.org
>http://mail.python.org/mailman/listinfo/tutor
>
>  
>
Ist,

You are not very explicit on either on what you on working with nor the 
sort of object that contains the data you are seeking to extract, hence, 
I will just outline an example of my own design.

Let's say you get you set of variables as a tuple: (var_1, var_2, ..., 
var_n) - I am going to assume these variables are names of lists.  So I 
see no real need to convert them to strings.  If that is indeed 
necessary, skip the entire discussion.

#Intermediate result
names_tuple = (var_1, var_2, ..., var_n)
len_tuple = len(names_tuple)
for j in range(len_tuple):
        try:
                len_obj = len(var_j)
                for i in range(len_obj):
                        value_of_obj(i) = var_i[i]
                         try:
                                print 'Show me the value of %s' %   
names_tuple[j],
                                print var_i[i]
                                # Or do whatever you have in mind, e.g. 
storing in a dictionary, etc.
                         except ValueError, TypeError, diag:      # 
regarding the errors I am guessing
                               print str(diag)
       except TypeError, RangeError, diag:
                 print str(diag)

I am not sure how useful you will find this nor how close it is to 
solving the problem you are attacking - just recognize I am new at 
python.  Moreover, I may miss the clues to the type of problem, since my 
specialty is databases and much of the discussion here leaves me a bit 
puzzled as to where they are being applied.

In any case, I hope it helps a bit.
Herschel