Is this pythonic?

[Tim Chase]

On 2016-11-23 22:15, Steve D'Aprano wrote:
> On Wed, 23 Nov 2016 08:10 pm, Frank Millman wrote:
> > The class has a getval() method to return the current value.
> > 
> > Usually the value is stored in the instance, and can be returned
> > immediately, but sometimes it has to be computed, incurring
> > further database lookups.  
> 
> This is called memoisation, or caching, and is a perfectly standard
> programming technique. It's not without its traps though: there's a
> famous quote that says there are only two hard problems in
> computing, naming things and cache invalidation.

Fortunately, you can offload some odd edge-cases to the standard
library, no?

  from functools import lru_cache
  # ...
  @lru_cache(maxsize=1)
  def getval(...):
    return long_computation()

It doesn't cache across multiple instances of the same class, but
does cache multiple calls to the same instance's function:

  >>> from functools import lru_cache
  >>> class Foo:
  ...   def __init__(self, name):
  ...     self.name = name
  ...   @lru_cache(maxsize=1)
  ...   def getval(self):
  ...     print("Long process")
  ...     return self.name
  ... 
  >>> f1 = Foo("f1")
  >>> f2 = Foo("f2")
  >>> f1.getval()
  Long process
  'f1'
  >>> f1.getval()
  'f1'
  >>> f2.getval()
  Long process
  'f2'
  >>> f2.getval()
  'f2'

-tkc