[Edu-sig] Python for Fun

[Kirby Urner]

Just for fun:  tweaking logic.py Connector class with 2.1 idioms:

    def connect (self, inputs) :
        if type(inputs) != type([]) : inputs = [inputs]
        self.connects += inputs  # <-- here

    def set (self, value) :
        if self.value == value : return      # Ignore if no change
        self.value = value
        if self.activates : self.owner.evaluate()
        if self.monitor :
            print "Connector %s-%s set to %s" % \
                  (self.owner.name,self.name,self.value)
        [con.set(value) for con in self.connects]  # <-- and here

Could also go:

   self.connects.extend(inputs)  (is that 1.5 or later?)

I find it interesting that you can define lists simply for 
their side-effects, with the list itself saved nowhere.  Indeed,
you can stick [1,2,3] (no assignment to a variable) anywhere 
a method and nothing happens -- __repr__ isn't triggered 
except at the command line.

I did have

  map(lambda con: con.set(value), self.connects)

which makes use of nested scopes (value in lambda is getting a 
pointer from the surrounding method), but list comprehension 
doesn't see this as a case of scope nesting i.e. variables 
within the brackets are locally scoped already.

Seems to me that list comprehension was already providing a 
way to work around some of little lambda's awkwardness, even
without the from __future__ import nested_scopes option.

Kirby