python - Storing logical conditions in a dictionary and passing them to if statements -

i have dictionary of logical conditions, i.e. == 1, need use in if statement evaluation. may not possible, wanted find out sure. sample code:

z = {'var1':['a == 1'],      'var2':['b == 3']     } = 6 b = 20  #if use dictionary value in if statement this:  if z['var1']:     print 'true' else:     print 'false'  #it evaluate true.  want statement #translate following form:  if == 1:     print 'true' else:     print 'false' 

i have been searching various permutations on if statements, list comprehensions , string manipulation, haven't found results matching problem. if not possible, i'd know. if there better approach, i'd know well. in advance answers.

you trying store expression, possible use built-in eval() function (you can use exec if want play around statements).

>>> = 6 >>> b = 3  >>> z = {         'var1':eval('a == 1'),         'var2':eval('b == 3'),     }  >>> if z['var1']:         print "true!"     else:         print "false!" false!  >>> if z['var2']:         print "true!"     else:         print "false!" true! 

note need assign variables before create expressions inside dictionary, expression evaluated @ run-time, nameerror exception raised if variable doesn't exist in memory.

>>> eval(foo) nameerror: name 'foo' not defined 

also wary eval() can dangerous if allow users input arbitrary strings argument. more here.

to explain why original code returning true, boolean expression if statement evaluating list containing 1 string. python evaluates non-empty sequences true, satisfy condition , string true printed.

>>> z['var1'] ['a == 1']  >>> bool(z['var1']) true