Functions vs OOP

tinnews at tinnews at
Sun Sep 4 10:13:49 CEST 2011

Ian Kelly <ian.g.kelly at> wrote:
> On Sat, Sep 3, 2011 at 10:15 AM, William Gill <noreply at domain.invalid> wrote:
> > During some recent research, and re-familiarization with Python, I came
> > across documentation that suggests that programming using functions, and
> > programming using objects were somehow opposing techniques.
> >
> > It seems to me that they are complimentary.  It makes sense to create
> > objects and have some functions that take those objects as arguments. Are
> > they suggesting that any function that takes an object as an argument should
> > always be a method of that object?  Conversely I can see creating functions
> > that take raw input (e.g. strings) and return it in a format compatible with
> > an object's constructor, rather than have objects accept any conceivable
> > format for its constructor.
> >
> > Am I missing something, or am I taking things too literally?
> I think you may be confusing "functional programming" and "programming
> using functions".  These are not the same thing.
> Functional programming is about using functions in the *mathematical*
> sense.  A mathematical function maps one value (or tuple of values) to
> another value.  The mapped value never varies; if it did, it would be
> a different function.  So functional programming eschews the use of
> functions where the results depend on any internal or external state
> beyond the values of the passed-in arguments, such as the variable
> state of the object the method is being called on.
I think there may be another issue here.  If someone says "functional
programming" to me then I would generally assume that they *do* mean
"programming using functions".  While your distinction of the two may
be strictly correct I don't think it's the generally accepted meaning.

Chris Green

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