Shoutbox

Original Subject: "dodgy bug in scripting"

With the current version (4.10.250), MsgPlus.Version returns 4.099999904632568, which is not equal to 4.10. I was wondering why this code didn't work as i expected

code:

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if (MsgPlus.Version < 4.10) {
    Debug.Trace("You have an old version of Plus");
}

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and I was surprised when I did "Debug.Trace(MsgPlus.Version);" and i showed 4.099999904632568.

confirmed, i got 4.09999990463257

Always use epsilon comparison (or something like that) when comparing floating-point numbers.

Well, at least that's what I do when I code in C/C++...

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But I think this can be fixed though...causing confusion for basic scripters.

quote:

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Originally posted by Mnjul
Always use epsilon comparison (or something like that) when comparing floating-point numbers.

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if in my code, that number (4.0999...etc) is not equal to 4.10, that means that 4.10 - 4.0999... is bigger than epsilon, so even if i've used epsilon, the comparision would have been different.

quote:

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Originally posted by Mnjul
But I think this can be fixed though...causing confusion for basic scripters.

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yes, of course; and not only for basic developers. For me its a pain to calculate, for each new version of plus, which is the value returned by msgplus.version... and not to mention that that value seem to be diferent depending on ... on what? NiteMare's Plus returns a value diferent from mine.

Fixed... nothing annoys me more than the stupid floating point data types of C++...

quote:

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Originally posted by Plus' changelog
Scripts MsgPlus.Version returns a more usable floating point value (see update in documentation).

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Well, in fact MsgPlus.Version returns a more usable value... for me it returns now 4.101010322570801, which in my code it works ok, but it still may fail, if you compare with ">" instead with "<" (because 4.101010322570801 is not the same as 4.10).

ok, ok... i'm being picky ... if I had to choose, i'd choose 4.101010322570801 (like it's now) instead of 4.099999904632568 (like before).

but maybe MsgPlus.Version could return an integer..., couldn't it? What about returning 4100 or 4010? That would make no confusion. I know, that changing the type (and value) of the returned number will cause backwards incompatibilities, but IMO, returning an integer would be the best option.

on the other hand, in the changelog, Patchou, you talk about a new documentation... where can we download it from? ... i know i should have read it before posting, maybe in the documentation there's something I haven't noticed

while playing with it (and reading up on som IEEE docs) I found:
http://babbage.cs.qc.edu/IEEE-754/Decimal.html

dunno how representative or usefull this is. Seems like single precision doesn't yield the accurate result, double precision does.

The documentation will be updated with an indication that the equal operator should not be used, instead, use "more than" or "less than". The change is that you'Re now guarenteed that the value returned will always be slighly above the exact version number, I can't do any better than that.

If you want a fixed integer, you already have it: the build number .

quote:

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Originally posted by CookieRevised
Seems like single precision doesn't yield the accurate result, double precision does.

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4.1 is a periodic number in base 2, it doesn't matter if you choose single or double precission

quote:

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Originally posted by Patchou

The documentation will be updated with an indication that the equal operator should not be used, instead, use "more than" or "less than". The change is that you'Re now guarenteed that the value returned will always be slighly above the exact version number, I can't do any better than that.

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it's ok with that

quote:

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Originally posted by Patchou
If you want a fixed integer, you already have it: the build number

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<picky mode>
i can't use the build number:

quote:

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Originally posted by scripts documentation
For safety reasons, the build number should always be paired with the major/minor version number of Messenger Plus!. Build numbers are not guaranteed to stay sequential between two new major versions of Messenger Plus!.

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just being picky
</picky mode>

Just check if its version 4 or 5 and you'll be ok with the build number