Learning Python now coming from Perl

[Roy Smith]

In article <slrngjps0o.51b.nick at irishsea.home.craig-wood.com>,
 Nick Craig-Wood <nick at craig-wood.com> wrote:
 
> My favourite mistake when I made the transition was calling methods
> without parentheses.  In perl it is common to call methods without
> parentheses - in python this does absolutely nothing!  pychecker does
> warn about it though.
> 
>   perl   -> $object->method
>   python -> object.method()

On the other hand, leaving out the parens returns the function itself, 
which you can then call later.  I've often used this to create data-driven 
logic.

For example, I'm currently working on some code that marshals objects of 
various types to a wire protocol.  I've got something like:

encoders = {
   SM_INT: write_int,
   SM_SHORT: write_short,
   SM_FLOAT: write_float,
   # and so on
}

class AnyVal:
   def __init__(self, type, value):
      self.type = type
      self.value = value

def write_anyval(any):
   encoders[any.type](any.value)

The fact that functions are objects which can be assigned and stored in 
containers makes this easy to do.