As a reference: In other EDA tools they can load newer files on older versions of the software. They just open a warning window with everything which is not readed/processed, and tell you everything not readed will be lost at next save.
Sent from my Android phone using TouchDown (www.nitrodesk.com) -----Original Message----- From: Wayne Stambaugh [stambau...@gmail.com] Received: Wednesday, 14 Jan 2015, 7:12PM To: Tomasz Wlostowski [tomasz.wlostow...@cern.ch]; kicad-developers@lists.launchpad.net Subject: Re: [Kicad-developers] file version compatibility (optional tokens in s-expression files) On 1/14/2015 11:27 AM, Tomasz Wlostowski wrote: > On 13.01.2015 20:11, Wayne Stambaugh wrote: >> This is a tricky issue that has been discussed before. The general >> consensus in the past has been not to support forward compatibility. It >> increases maintenance and complexity of the file parser for a minimal >> net gain to the user. My preference is to force users that want to >> bleed on the edge to use nightly builds rather than try to maintain any >> forward file compatibility. > > Hi Wayne, > > The only argument I see for limited forward compatibility is when > someone uses a bleeding edge build to benefit from the latest features > (or just adds them them as needed), but must be able to share the design > (read only is OK) with other people who are forced to stick to the > stable version (think of corporate/university users where software is > centrally managed by some IT department). > >> I also don't like idea of creating special tokens just for version >> compatibility. I would like to keep the file format as readable as >> possible. My guess is that any version compatibility tokens will have >> to reference the other objects in the file making the file less readable >> which is something that I will be reluctant to support. > > I didn't consider impact on file readability. I'm not the type who edits > graphics with a text editor (and a PCB, after all is mostly a graphical > design), so as long as the file structure is easy to figure out, I'm OK > with it. I understand your point though and I'm not going to argue here > (especially given the fact that you've put quite a lot of effort to make > the format readable). > >> >> How do you plan to prevent data loss when editing newer files with older >> versions of pcbnew? > > > >> One solution might be to ignore any unsupported tokens and warn the user >> that there may (will?) be data loss if the board is modified and saved. >> Even this solution I think has a lot of potential pitfalls. Make newer >> files read only is also a possibility. >> >> The only way I would support forward file compatibility is if there is: >> >> a) no loss of file readability >> b) no loss of user data >> d) no unnecessary increase in the complexity of the file parser code. >> c) no hoard of angry users who want to edit a new file version with and >> older version of pcbnew. > > OK, how about this: > - No extra version tokens (fits point A) > - Warning instead of error on unrecognized tokens (point C - no big > changes needed in the parser) > - If the opened file is produced by a newer version of Kicad, issue a > big warning when the user attempts to save it, that certain features > will be lost (points B and D - if somebody complains we can always tell > him he was warned). AFAIK this is what most commercial software does. This seems plausible but a bit risky. How would you handle new file objects that an older version of pcbnew knows nothing about? These objects would not be rendered and the user might get a false sense of security that a complete file load was performed. A warning may work or it may not. I guess you get to pick who you want to scream at you. The user who can't open a new file version or the user who just lost valuable file information. Pick your poison. I'm more comfortable telling people to upgrade rather than saying "Sorry, you were warned". > > Cheers, > Tom > > _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : kicad-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
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