A java hobbyist programmer learning python

[elhombre]

"Steven D'Aprano" <steve at REMOVE-THIS-cybersource.com.au> wrote in message 
news:0182896d$0$8693$c3e8da3 at news.astraweb.com...
> 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

Excellent links. Thanks Steven !