On Sun, 18 Jan 2009 11:11:45 +1000, elhombre wrote: > Hello, below is my first fragment of working python code. As you can see > it is very java like as that is all I know. Is this the right approach > to be taking?
You might find it very useful to read: http://dirtsimple.org/2004/12/python-is-not-java.html http://dirtsimple.org/2004/12/java-is-not-python-either.html > Should I be taking a different approach? Thanks in advance. This is obviously a very minimal program, so I won't criticise you for failing to do any error checking :-) However, I will make some broad points: * No getters and setters. Python takes a very permissive approach to class attributes, taking the philosophy "we're all adults here". It's easy to change a public attribute to a private attribute with a getter/ setter if you need to, so there's nothing to be gained by writing getters for straight attribute access. It just makes things slow. * Don't return error values, raise an exception. Setting up a try...except block is really fast in Python, almost as fast as a pass statement (according to my tests). Catching the exception itself is slow, but most of the time you won't care about that. Let me re-write your code in a more Pythonic way. This is not the only way to do this, and it probably isn't the best way, but it may give you a flavour for the way Python is usually written. import sys import operator class Calculator(): dispatch = { # dispatch table mapping symbol to function '+': operator.add, '-': operator.sub, '*': operator.mul, '/': operator.truediv, } def __init__(self): self.operator = sys.argv[1] self.arg1 = int(sys.argv[2]) self.arg2 = int(sys.argv[3]) def calculate(self): func = self.dispatch[self.operator] return func(self.arg1, self.arg2) if __name__ == '__main__': # run this block only when running as a script, not # when the module is being imported (say, for testing). x = Calculator('+', 23, 42) try: y = x.calculate() except KeyError: print "Unrecognised operator '%s'" % x.operator else: print y -- Steven -- http://mail.python.org/mailman/listinfo/python-list
