sane-project-website/old-archive/1999-08/0299.html

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<title>sane-devel: Re: SANE V2</title>
<h1>Re: SANE V2</h1>
<b>Oliver Rauch</b> (<a href="mailto:oliver.rauch@Wolfsburg.DE"><i>oliver.rauch@Wolfsburg.DE</i></a>)<br>
<i>Wed, 25 Aug 1999 19:23:58 +0200</i>
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Nick Lamb wrote:<br>
<p>
<i>&gt; Some time after SANE_FRAME_BLAH is established we discover that the</i><br>
<i>&gt; existing backends and frontends have co-incidentally implemented</i><br>
<i>&gt; the same wrong behaviour. We could then re-write all the software,</i><br>
<i>&gt; and require users to upgrade immediately, or we could just do this:</i><br>
<i>&gt;</i><br>
<i>&gt; SANE_FRAME_BROKEN_BLAH = old value of SANE_FRAME_BLAH</i><br>
<i>&gt; SANE_FRAME_BLAH = newly issued frame type number</i><br>
<i>&gt;</i><br>
<i>&gt; Which makes it possible to auto-detect broken frames from the old</i><br>
<i>&gt; broken backends in a new frontend, and correct for it (if possible)</i><br>
<i>&gt; or at least avoid nasty surprises.</i><br>
<i>&gt;</i><br>
<p>
Hi Nick,<br>
if we use identifiers that do not say anyting we of course can change<br>
the meaning of this identifier without any probelms.<br>
<p>
But I think the advantages of identifiers who say something about the<br>
thing they identify is much more better than numbers.<br>
<p>
The second thing is that if we use a string as identifier we do not have<br>
to change sane.h all the time when we add a new format.<br>
That can make much problems, here only one example:<br>
( We will not distribute all frontends and the backends together in the future,<br>
this is the reason why xsane is not included into the sane package. )<br>
You can not find out with precompiler test (#ifdef ...) if there is a member<br>
in the enum or not. So if you try to compile a frontend that tries to uses<br>
a new frame format (SANE_FRAME_NEW_XYZ) but that one is<br>
not defined in the enum you get much problems that are not easy to<br>
solve.<br>
<p>
Bye<br>
Oliver<br>
<p>
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EMAIL: <a href="mailto:Oliver.Rauch@Wolfsburg.DE">Oliver.Rauch@Wolfsburg.DE</a>
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<li> <b>Next message:</b> <a href="0300.html">Oliver Rauch: "Re: SANE V2"</a>
<li> <b>Previous message:</b> <a href="0298.html">Harald Finster: "Re: microtek X6 advance and TMA"</a>
<li> <b>Maybe in reply to:</b> <a href="0296.html">Nick Lamb: "SANE V2"</a>
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<li> <b>Next in thread:</b> <a href="0300.html">Oliver Rauch: "Re: SANE V2"</a>
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