properties vs. eval()

[Bob Rogers]

Given this class:

class C(object):
    def set_x(self, x):
        self._x = x

    def get_x(self):
        return self._x

    x = property(get_x, set_x)


This use of compile() and eval() works as I expected it to:

    c = C()
    c.x = 5000
    n = '\'five thousand\''
    code = compile('c.x = ' + n, '<input>', 'exec')
    print 'before ', c.x
    eval(code)
    print 'after  ', c.x

But this, using eval() without compile(), does not:

    c = C()
    c.x = 5000
    n = '\'five thousand\''
    print 'before ', c.x
    eval('c.x = ' + n)
    print 'after  ', c.x

It gives:

    before  5000
    Traceback (most recent call last):
      File "./r.py", line 16, in ?
        eval('c.x = ' + n)
      File "<string>", line 1
        c.x = 'five thousand'
            ^
    SyntaxError: invalid syntax

Could someone please explain just what is going on here, and whether it
is possible to dispense with the compile step and use eval() alone
while setting a property?

Thanks.