How to reference variable dynamically in Python?

Question

I have the following code:

PROJECT_ID = 'test'
BQ_TABLE_NAME_CATEGORIES = 'categories'
BQ_TABLE_NAME_MANUFACTURERS = 'manufacturers'
list = [BQ_TABLE_NAME_CATEGORIES, BQ_TABLE_NAME_MANUFACTURERS]
table_categories = PROJECT_ID + '.' + BQ_TABLE_NAME_CATEGORIES
table_manufacturers = PROJECT_ID + '.' + BQ_TABLE_NAME_MANUFACTURERS
for table in list:
 ....
 source_objects=['table_{0}'.format(table)] #reference to the correct var
 ....

This however puts string inside source_objects. I want it to reference the variables (whatever is saved in the variables) meaning what I actually want is equivalent of this:

When table = BQ_TABLE_NAME_CATEGORIES

source_objects = [ table_categories ] 

When table = BQ_TABLE_NAME_MANUFACTURERS

source_objects = [ table_manufacturers ] 

• saud: Are you trying to get the contents on table_categories inside a list? Or do you just want to reference it's string value?
• saud: Also, it is bad practice to override the built-in list object.
• Luis: @RottenCandy I want the refrence... source_objects should contain whatever table_categories contains.. Just like I would do : source_objects = [ table_categories ]

Answer 1

you can use the eval() function to turn strings into variable: read on eval

PROJECT_ID = 'test'
BQ_TABLE_NAME_CATEGORIES = 'categories'
BQ_TABLE_NAME_MANUFACTURERS = 'manufacturers'
mylist = [BQ_TABLE_NAME_CATEGORIES, BQ_TABLE_NAME_MANUFACTURERS]
table_categories = PROJECT_ID + '.' + BQ_TABLE_NAME_CATEGORIES
table_manufacturers = PROJECT_ID + '.' + BQ_TABLE_NAME_MANUFACTURERS
for table in mylist:
 source_objects=eval('table_{0}'.format(table)) #reference to the correct var
 print source_objects

output:

test.categories
test.manufacturers

also as noted in comments, you really shouldn't override list, and use mylist or whatever instead

Answer 2

If I understand your question correctly, what you are trying to do is store the values of table_categories and table_manufacturers inside a list called source_objects. Assuming the table_... variables are global,

suffixes = [BQ_TABLE_NAME_CATEGORIES, BQ_TABLE_NAME_MANUFACTURERS]
source_objects = []
for s in suffixes:
 source_objects.append(globals['table_{0}'.append(s)])
 ...

This would get you:

>>> source_objects
['test.categories', 'test.manufacturers']

And if the table_... variables are not global, use locals(). See https://docs.python.org/3/library/functions.html#globals