A friendlier, sugarier lambda -- a proposal for Ruby-like blocks in python

Kay Schluehr kay.schluehr at gmx.net
Sun Oct 15 10:17:13 CEST 2006


Paul Boddie wrote:
> Kay Schluehr wrote:
> >
> > Spreading tiny function definitions all over the code
> > may be finally not such a good idea compared with a few generic methods
> > that get just called? OO might run out of fashion these days but Python
> > is not Java and Pythons OO is pretty lightweight.
>
> I think you've successfully identified a recent trend in Python
> development: the abandonment of fairly transparent object-oriented
> techniques in favour of more opaque but supposedly more convenient
> hybrid techniques. Unlike Java, Python's first class functions and
> methods are already highly useful for callback-based systems - such
> systems in Java suffer from interface proliferation and needless
> one-off class definitions - but it seems to me that the subsequent
> language evolution in favour of anonymous blocks brings fewer benefits
> and can, as you say, diminish readability.

I was actually more concerned about extensibility than readability.
Talking about classes being lightweight I mentioned classes to be
"first-class" objects and intended constructions like this:

class fetchPage_event(fetchPage('http://python.org')):
    def _showResponse(self, response)
        print "fancy formatting: %s" % response.text

where all the registration and framework magics happens when the
fetchPage_event class is created. Adding "callbacks" just happen when
you add a method to the class. Here you have your "block" with no
additional syntax. You can pass the fetchPage_event class around and
add and overwrite methods in subclasses in the same fashion. A subclass
can be created within any statement on the fly etc. Here you have an OO
solution that is both short and has a clean design.




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