How to assign value to the output of eval function in python -

i tried assign value output of eval function below:

d = {"a": 10} st1 = 'd' st2 = '["a"]' eval(st1 + st2) = 15 

i got error:

file "<stdin>", line 1 syntaxerror: can't assign function call 

i tried this:

x = eval(st1 + st2) x = 15 

but doesn't change d dictionary. tried eval whole assignment this:

eval(st1 + st2 + ' = 15') 

but got error:

traceback (most recent call last): file "<stdin>", line 1, in <module> file "<string>", line 1   d["a"] = 15          ^ syntaxerror: invalid syntax 

i have tried use ast.literal_eval() function , results same. so, idea how it??

edit 1:

for clarification @lennartregebro requested for, should have dictionaries specific key , value pairs. have text file user , of these values defined there , should change basic dictionaries values these user defined ones. have parser parses text file , each change, gives me tuple containing dictionary name, key , value; strings. wanted assignments eval function, understood can't.

edit 2:

as @lejlot suggested, used globals() , added below lines code:

import re pattern = re.compile(r'\["([a-za-z0-9_\./\\-]+)"\]') globals()[st1][pattern.findall(st2)[0]] = 15 

why don't access variables through globals() (or locals()) instead of eval?

d={'a':10} globals()['d']['a']=15 print d['a'] 

in particular case

d={'a':10} s1='d' s2='a' globals()[s1][s2]=15 print d['a']