eval SyntaxError: invalid syntax in python

For dynamic execution of statements use the exec function:

>>> exec('y = 3')
>>> y
3

eval usage: eval(expression).

The expression argument is parsed and evaluated as a Python expression.

e.g.:

>>> s = 3
>>> eval('s == 3')
True
>>> eval('s + 1')
4
>>> eval('s')
3
>>> eval('str(s) + "test"')
'3test'

eval() only allows for expressions. Assignment is not an expression but a statement; you'd have to use exec instead.

Even then you could use the globals() dictionary to add names to the global namespace and you'd not need to use any arbitrary expression execution.

You really don't want to do this, you need to keep data out of your variable names and use a list or dictionary instead:

x = ['123'] * 10

would give you a list you can address as x[0], x[1], etc. without having to execute arbitrary expressions.