On Thu, 13 Sep 2012 10:23:22 +0200, Peter Otten wrote:
> MRAB wrote:
>
>> On 12/09/2012 19:04, Alister wrote:
>>> On Wed, 12 Sep 2012 18:56:46 +0200, Jabba Laci wrote:
>>>
>>>>> For example:
>>>>>
>>>>> def install_java():
>>>>> pass
>>>>>
>>>>> def install_tomcat():
>>>>> pass
>>>>
>>>> Thanks for the answers. I decided to use numbers in the name of the
>>>> functions to facilitate function calls. Now if you have this menu
>>>> option for instance:
>>>>
>>>> (5) install mc
>>>>
>>>> You can type just "5" as user input and step_5() is called
>>>> automatically. If I use descriptive names like install_java() then
>>>> selecting a menu point would be more difficult. And I don't want
>>>> users to type "java", I want to stick to simple numbers.
>>>>
>>>> Laszlo
>>>
>>> No No NO!
>>> you cant just pass user input to system calls without validating it
>>> first (google sql injection for examples of the damage unsanitised
>>> input can cause, it is not just as SQL problem)
>>>
>>> it is just as easy so select a reasonably named function as a bad one
>>>
>>> option=raw_input('select your option :')
>>>
>>> if option =="1": install_java()
>>> if option =="2": install_other()
>>>
>>> alternatively you cold add your functions into a dictionary an call
>>> them from that
>>>
>>> opts={'1':install java,'2':install_other}
>>>
>>> option=raw_input('select your option :')
>>> opts[option]
>>>
>>> Poorly named functions are a major example of poor programming style.
>>>
>>> one of the fundamental pillars for python is readability!
>>>
>> Or you could do this:
>>
>>
>> def install_java():
>> "Install Java"
>> print "Installing Java"
>>
>> def install_tomcat():
>> "Install Tomcat"
>> print "Installing Tomcat"
>>
>> menu = [install_java, install_tomcat]
>>
>> for index, func in enumerate(menu, start=1):
>> print "{0}) {1}".format(index, func.__doc__)
>>
>> option = raw_input("Select your option : ")
>>
>> try:
>> opt = int(option)
>> except ValueError:
>> print "Not a valid option"
>> else:
>> if 1 <= opt < len(menu):
>> menu[opt - 1]()
>> else:
>> print "Not a valid option"
>
> I'd still argue that a function index is the wrong approach. You can use
> tab completion to make entering descriptive names more convenient:
>
> import cmd
>
> class Cmd(cmd.Cmd):
> prompt = "Enter a command (? for help): "
>
> def do_EOF(self, args):
> return True
> def do_quit(self, args):
> return True
>
> @classmethod def install_command(class_, f):
> def wrapped(self, arg):
> if arg:
> print "Discarding argument {!r}".format(arg)
> return f()
>
> wrapped.__doc__ = f.__doc__
> wrapped.__name__ = f.__name__ class_._add_method("do_" +
> f.__name__, wrapped)
> return f
>
> @classmethod def _add_method(class_, methodname, method):
> if hasattr(class_, methodname):
> raise ValueError("Duplicate command
> {!r}".format(methodname))
> setattr(class_, methodname, method)
>
> command = Cmd.install_command
>
> @command def install_java():
> "Install Java"
> print "Installing Java"
>
> @command def install_tomcat():
> "Install Tomcat"
> print "Installing Tomcat"
>
> if __name__ == "__main__":
> Cmd().cmdloop()
To be honest I prefer the "if X do Y" approach for readability but a
dictionary can be undated dynamically & used to automatically create the
menu so it can have its place
--
I'll see you... on the dark side of the moon...
-- Pink Floyd
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