[melbourne-pug] Coding idiom

[Bill Birch]

On Fri, 5 May 2006 10:57 am, Maurice Ling wrote:

>
> I am hoping that Bill's type system is able to strike a middle ground on
> this, allowing developers to define their own coding conventions which
> is mappable to a standard type system as metaknowledge, or something
> like that.
>
Hi,

A type system would help reason about the code. There's been various proposals 
to add "interfaces" a la Java to Python. These have merit to solve this 
issue. The technique is to first define an interface or interfaces, then the 
implementation class methods or attributes that are not in in the interfaces 
are effectively private. By declaring interfaces you are publically 
committing to honour some methods, but caveat user on the others.  Because 
the interface is separated you don't have the issues with underscores in  
names. The type system just allows you to capture the method signatures and 
have code to introspect them at runtime.

Zope has an interface package which you can use right now. I have not used it 
(yet). Has anyone? It looks clunky. 
http://svn.zope.org/Zope3/trunk/src/zope/interface/README.txt?view=markup

You -could- use a decorator to scare people away:

def private(x) : return x
def protected(x) : return x
def public(x) : return x

class Ubeaut(object):

	@private
	def hairyDetailedFunctionNoOneShouldUse(self): pass

	@public
	def goForIt(self): pass

Not very original. But is blindingly obvious what you mean. If you stick with 
this system one day you could code up something more snazzy than the identity 
function. 

Personally I am against using underscores to  give subtle meanings, and I am 
glad we have decorators. Perhaps one day the magic underscore behaviour of 
import will be replaced with a decorator. 


-- 
http://billbirch.wordpress.com/