Gentoo Archives: gentoo-dev

From: Ciaran McCreesh <ciaran.mccreesh@××××××××××.com>
To: gentoo-dev@l.g.o
Subject: Re: [gentoo-dev] Happy 10th birthday (in advance)
Date: Sat, 31 Mar 2012 16:05:20
Message-Id: 20120331170212.15001004@googlemail.com
In Reply to: Re: [gentoo-dev] Happy 10th birthday (in advance) by Alex Alexander
1 On Sat, 31 Mar 2012 18:39:21 +0300
2 Alex Alexander <alex.alexander@×××××.com> wrote:
3 > On Mar 31, 2012 5:57 PM, "Ciaran McCreesh"
4 > <ciaran.mccreesh@××××××××××.com> wrote:
5 > > On Sat, 31 Mar 2012 15:08:29 +0300
6 > > Alex Alexander <alex.alexander@×××××.com> wrote:
7 > > > No. I didn't say I think it works, I said I have proof it works.
8 > >
9 > > Well that's interesting, because there are plenty of examples where
10 > > it doesn't work, and all that it takes to disprove a theory is a
11 > > single counterexample. So I think you're misunderstanding what
12 > > constitutes proof here -- "some evidence" certainly isn't it.
13 >
14 > Boring. You conveniently ignored the other part of my message.
15
16 I was hoping you'd understand how your claim of proof was utterly
17 unfounded. What you have is limited evidence of a very specific
18 situation, which is a whole other thing.
19
20 > I'll repeat it: no matter how much you argue, it'll still work fine
21 > for me.
22
23 And I'll spell it out. On the scale of "it works", you have a series of
24 levels:
25
26 1. It compiles.
27
28 2. I tried it and I didn't see any breakages.
29
30 3. I tried it, and I checked carefully that nothing was broken.
31
32 4. I tried it on a wide range of valid inputs, and I checked carefully
33 that nothing was broken.
34
35 5. I tried it on a wide range of valid inputs, including inputs designed
36 to test edge cases, and I checked carefully that nothing was broken.
37
38 6. I tried it on a wide range of valid and invalid inputs, and I
39 checked carefully that nothing was broken, and that the invalid inputs
40 were handled correctly.
41
42 7. I carefully considered all the equivalence classes of inputs, and
43 tested each.
44
45 8. I carefully considered all the equivalence classes of inputs, and
46 can explain why each is handled correctly.
47
48 9. I can prove that it works.
49
50 You're offering evidence of number 2, or possibly 3. Gentoo is a large
51 system containing many interacting components, that is expected to keep
52 working for long periods in many different unpleasant situations. We
53 need to be at at least number 7 here, and ideally number 8. For preserve
54 libs, the feature fails at number 4.
55
56 --
57 Ciaran McCreesh

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