Re: OO versus RDB

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sun, 09 Jul 2006 16:54:42 GMT
Message-ID: <mxasg.8295$pu3.185742@ursa-nb00s0.nbnet.nb.ca>

Marshall wrote:

> Adrian Hey wrote:
>

>>Marshall wrote:
>>
>>>What I said is true: a function that doesn't read any
>>>external variables but does write to them will have its
>>>return value entirely determined by its parameters.
>>
>>What's wrong about this statement is that such things are not functions.
>>If you want to substitute another word (like "procedure") that would be
>>fine.

>
> You seem quite concerned about words. Do you have anything
> of substance to contribute, or are you just all about the dictionary?
>
>
>

>>>This is just arguing about what the definition of the term "pure" ought
>>>to be. Not very interesting.
>>
>>Perhaps you'd find it a little more interesting if it was your job to
>>write an optimising compiler that doesn't break programs.

>
> What my job is has no bearing on whether arguments about
> which definition of a term is right are interesting or not. Such
> arguments are always uninteresting. It is the semantics behind
> them that are interesting. I keep focusing on the semantics
> and you keep arguing about the defintions. So far you have
> not said anything of interest. Although you have amply
> demonstrated my earlier point, which is that people get
> unbalanced when you point out that return values are not
> affected by writing to global variabes.

Observable effect, on the other hand, is affected. Thus, such a function is not a pure function according to the definitions I have seen. Now, if the variable were a static variable not observable outside the function, then it would be pure. Received on Sun Jul 09 2006 - 11:54:42 CDT