Dethe Elza:
Thanks a lot for mentioning that.

rcriii:
That looks cool. Thanks for posting your version.

self.operations = {'+':lambda o1, o2:o1+o2,
                              '-':lambda o1, o2:o1-o2,
                              '*':lambda o1, o2:o1*o2,
                              '/':lambda o1, o2:o1/o2,
                              '^':lambda o1, o2:o1**o2}

The isOperator becomes:
def isOperator(self, char):
                """Checks whether the last item entered in the stack is an operator or not"""
                if char in self.operations.keys():
                        return True
                else:
                        return False

and Operate() becomes:

def operate(self, operator):
                """"Perform the stated operation on the last two elements in the stack"""
                operand1 = float(self.stack[-1])
                operand2 = float(self.stack[-2])

                self.stack.pop()
                self.stack.pop()

                    self.stack.append(self.operations[operator](operand1, operand2))

And adding operators becomes quite easy.

>>> int(’012345′)
12345

but

>>> int(’012345′, 8)
5349

“Explicit is better than implicit” strikes again

Everyone Else
Thanks for answering my question.

Oc tal octaaaaaaaaaaaallllllll!

A couple of suggestions for the Python code: the de facto standard indentation, also blessed by the official style guide (PEP 8) is 4 spaces per level, not 8.

You can express the operator check more concisely as
return char in ['+', '-', '*', '/']

Also, ‘char’ is not a particularly good name since it may well be a multi-character string containing a floating point number.

list.pop() defaults to popping the last item, so passing -1 is redundant.

You’ve already converted both operands to floats when you extracted them from the stack (personally, I’d convert them when inserting into the stack, but whatever), so there’s no need for a repeated conversion where you’re implementing division. On the other hand, this may be a place where explicit is better than implicit.

Machine.__init__ ignores the stack argument. Also beware of using mutable types such as lists for default argument values, you can easily end up sharing objects without intending to do so.

I’d also use ‘return’ in place of ‘raise SystemExit’.

That would be octal. From http://java.sun.com/docs/books/tutorial/java/nutsandbolts/datatypes.html:

“”"
The prefix 0 indicates octal, whereas 0x indicates hexadecimal.

…
int octVal = 032; // The number 26, in octal
“”"