Re: [Pan-users] Making Pan behave like OE/Windows Mail

[Steven D'Aprano]

On 28/01/13 08:55, Joe Zeff wrote:
> On 01/27/2013 01:00 PM, David WE Roberts wrote:
> > I still don't understand why the latest threads want to snuggle up next to
> > the negative scores instead of the positive scores.
>
> Sorting on several fields can be quite tricky. I remember, once, many
>  many years ago, changing a very slow bubble sort of a list of customers
>  to a shell sort that took 5% of the time. The data entry person
> complained because the sort wasn't "stable." That is, if there were
>  multiple customers with the same last name (what I was asked to sort
>  on) the new list didn't keep the customer numbers in correct order,
>  something I'd not been asked to do.[1]


If you're not asked for a stable sort, you can't exactly be criticised for not 
providing a stable sort. Much.

In practice, "sorting should be stable" should be one of those no-brainers for 
user-facing applications. A bit like, "what do you mean, you wanted the Save command to 
actually write the data to disk? Nobody specified that in the spec!"

(Aside: or an oven that can actually heat up food. My oven has *three* off 
settings. There's OFF, and then there's LIGHT, and then there's FAN. To 
actually turn the heating element on, you need to set it to FAN ASSIST. I can't 
tell you how many times I've turned the oven on and wondered why it wasn't 
warming up because I had it on FAN instead of FAN ASSIST.)


> [1]She'd asked for this because with the old routine she could have
> printed out the list on index cards and hand sorted them faster. I
> never said it, but I couldn't help thinking that some people are never
> satisfied, even if they get exactly what they asked for.

What they ask for is not necessarily what they were expecting, because they 
thought that it went without saying. Or they didn't realise they needed it 
until it was gone. This is why all specs should always go through at least two 
iterations.

The correct answer to "But this is what you asked for" is often "Yes, and now that 
you've delivered it, I realise that it's not what I need".



--
Steven