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Addressing the question for variable variables in python (i.e. variables with variable names), which has been posed on stackoverflow: http://stackoverflow.com/questions/1373164/how-do-i-do-variable-variables-in-python

The consensus is to use a dictionary for this. This is a good idea for most cases, however, there are many aspects arising from this:

• you'll yourself be responsible for this dictionary, including garbage collection (of in-dict variables) etc.
• there's either no locality or globality for variable variables, it depends on the globality of the dictionary
• if you want to rename a variable name, you'll have to do it manually
• however, you are much more flexible, e.g.
  • you can decide to overwrite existing variables or ...
  • ... choose to implement const variables
  • to raise an exception on overwriting for different types
  • etc.

Some Examples:

from variableVariablesManager import VariableVariablesManager

myVars = VariableVariablesManager()
myVars['test'] = 25
print(myVars['test'])

# define a const variable
myVars.defineConstVariable('myconst', 13)
try:
    myVars['myconst'] = 14 # <- this raises an error, since 'myconst' must not be changed
    print("not allowed")
except AttributeError as e:
    pass

# rename a variable
myVars.renameVariable('myconst', 'myconstOther')

# preserve locality
def testLocalVar():
    myVars = VariableVariablesManager()
    myVars['test'] = 13
    print("inside function myVars['test']:", myVars['test'])
testLocalVar()
print("outside function myVars['test']:", myVars['test'])

# define a global variable
myVars.defineGlobalVariable('globalVar', 12)
def testGlobalVar():
    myVars = VariableVariablesManager()
    print("inside function myVars['globalVar']:", myVars['globalVar'])
    myVars['globalVar'] = 13
    print("inside function myVars['globalVar'] (having been changed):", myVars['globalVar'])
testGlobalVar()
print("outside function myVars['globalVar']:", myVars['globalVar'])

If you wish to allow overwriting of variables with the same type only:

myVars = VariableVariablesManager(enforceSameTypeOnOverride = True)
myVars['test'] = 25
myVars['test'] = "Cat" # <- raises Exception (different type on overwriting)

Project Members:

• Dominik R. (admin)