John, I want to go back to the beginning of our discussion that led to a new atmos.cxx and altimeter.cxx. My reason for wanting this code to read the baro setting from the property tree and return to the tree the baro offset is to make sure it is clear that these are different than the altimeter setting and kollsman shift and can/should be different in two types of pilot error. Not being clear in terminology and semantics was one of your original complaints about the existing code.
On Sun, 2007-02-11 at 00:22 -0500, John Denker wrote: > While we're in the vicinity: > > Both the Weather Conditions popup and the atis.cxx code rely > on the "pressure-sea-level-inhg" property and use it in ways > that the altimeter setting should be used. > > This is at least a misnomer, and probably a misconception. > The altimeter setting is not the same thing as the sea-level > pressure. The altimeter setting is something else; it is > properly called the altimeter setting. It is also properly > called the QNH, although private pilots who fly only in > the US may be unfamiliar with the QNH terminology. You convinced me of this. They are different. > > This property needs to be expunged and replaced with > something else, something with a correct name and with > correct semantics. > Why does this argument apply to the above 2 of the three variable I point out as my rational for adding 5 lines of c++ to your altimeter.cxx, but not to the third. The "setting" refers to what is entered in the kollsman window and the baro setting refers to what is entered in the kap140. Even with a separate instantiation referred to as an encoder, not having these 5 lines of code forces the user to have save the baro setting variable to the autopilot baro setting location as well as the encoder "setting" location. This is exactly the type confusing and incorrect semantics you set out to eliminate. Then you suggest that the autopilot nasal should fetch the indicated altitude from the encoder and the pressure altitude from the encoder and subtract to get the baro setting offset. Again adding to the possibility of future confusion and just plane hard to read code. With the 5 additional lines, all using non ambiguous names we avoid what you set out to avoid. I had proposed this subtraction method to Roy off list and he did not want to use a value that was unavailable in real life to the kap140. Regards, -- Dave Perry ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
