Re: Avoiding side effects

["(see below)" <yaldnif.w@blueyonder.co.uk>]

On 08/10/2008 06:16, in article u1vyrbra1.fsf@no.email.thanks.invalid,
"Anders Wirzenius" <anders@no.email.thanks.invalid> wrote:

> "(see below)" <yaldnif.w@blueyonder.co.uk> writes:
> 
>> On 07/10/2008 15:47, in article uprmc4g3i.fsf@no.email.thanks.invalid,
>> "Anders Wirzenius" <anders@no.email.thanks.invalid> wrote:
>> 
>>> "(see below)" <yaldnif.w@blueyonder.co.uk> writes:
>>> 
>>>> On 07/10/2008 12:08, in article wvbrfxn8hdc7.fsf@sun.com, "Ole-Hjalmar
>>>> Kristensen" <ole-hjalmar.kristensen@substitute_employer_here.com> wrote:
>>>> 
>>>>> Yes, I think any program which use a read/write interface to a file
>>>>> will have side effects in that sense. The only way I can think of for
>>>>> avoiding this would be to mmap the whole file, then it will appear as
>>>>> an array of bytes.
>>>> 
>>>> Why would stepping through an array not be thought a "side" effect?
>>> 
>>> A function that returns the row of that array and only that
>>> would perhaps be a function without side effects. The information
>>> in that row can be fetched when needed.
>> 
>> A function that always returns the same row of an array would be of little
>> use, I should think.
> 
> I have a feeling that the function can be programmed so that it returns
> different row (numbers, or pointers in that array) depending on
> the content of the rows in that array ;-)
> 
> function Row_Number (Row_Number_In_Other_Array : in
>                      Row_Number_Type)  return Row_Number_Type is
>    --  Return a row number one higher than the row number of the row
>    --  identical to the row in the other array.
> 

I think this beautifully illustrates the silliness that slavish adherence to
dogma inevitably produces, in programming as in finance and politics.

-- 
Bill Findlay
<surname><forename> chez blueyonder.co.uk