Functions vs OOP

[MRAB]

On 03/09/2011 17:15, William Gill 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.

I think you mean "complementary". :-)

> 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 that it's all about "state".

In functional programming, there's no state; a function's result
depends solely on its arguments, so it will always return the same
result for the same given arguments.

In OOP, on the other hand, an object often has a state; a method may
return a different result each time it's called, even for the same
given arguments.