Hi List, I'm writing to describe an optional feature which I added to master, and an optional and very small dependency I added which supports it. There was some minor controversy on irc whether I should have mailed the list before doing this -- I think in this case it is small enough and unimportant enough that it's okay but I have figured that I should mail the list about it anyways.
Earlier last week I tried to create a "lua interpreter console" dialog where you can interactively send commands to the in-game lua. I did this because I felt we were missing something like the "gamestate inspector" to help inspect the lua state as a debugging aid, and I am anticipating that I will develop more lua-based stuff in the near future. It is mostly working and so a few days ago I called it finished after adding some bells and whistles. One of the features which I added was a command history. I looked around at what most programming language interpreters do and it turns out that the majority of them use GNU Readline for many reasons. Besides those written in C, Readline is also available as a popular python module. Readline is GPL v2 and apparently is good enough that some projects have switched to a GPL license to take advantage of it: http://en.wikipedia.org/wiki/GNU_Readline#Implications_of_GNU_Readline.27s_GPL_license In fact readline is also an optional dependency of lua -- if we compiled the lua folder in current master with appropriate symbol definitions, we could create a stand-alone lua interpreter backed up by readline. GNU history is the small subset of readline which is related to command line history. Besides search and recall, it supports automatically saving and recalling the history session to a file, and bash-style history expansions in strings. I decided that it would probably be easier and more interesting to use GNU history rather than reimplement something like this based on std::vector<std::string> or whatever, surely a pretty menial task if you don't care about the persistence or "expansions". It took me about an hour or two read about it and implement it to my satisfaction this way. It took me about another hour or two to successfully cross-compile GNU history with mingw32 at gfgtdf's request. Thanks also to gfgtdf for finding a bug in my implementation also. Having done all this though, I'm not really about to argue or litigate to add this as an official dependency -- frankly I don't really care. Only a tiny fraction of users would actually use the lua console anyways, only if they are developers or advanced UMC makers. Fewer still would even notice or particularly care about a command line history feature. And I'm certainly not willing to spend more time arguing about the feature than I did implementing it, so I'm already pretty nearly tapped out in that regard. Why put this on master then. Well, the fact is that this library is widely available, it's a dependency of bash, so for instance most of our linux users already have it installed. I have set up scons to search for the lib by default, but if it fails then proceed without it. So it works like the optional dbus-1 dependency. It didn't occur to me at the time that anyone would think this course of action would be unreasonable, or would want to argue about it -- it adds some minor convenience for some users without inconveniencing anyone else. In a way this is a pretty awkward email, because I'm not really interested in starting a discussion, and I'm also not interested in rewriting or revisiting the feature for really any reason. Rather I just don't want anyone to jump to conclusions, feel miffed and say I inconvenienced them by adding a stealth dependency. If everyone wants it to be removed, fine, I don't intend to post in the topic again, I will just use the feature privately myself. If everyone would much rather have a version of the feature without the dependency, you are of course quite welcome to take advantage of the space between #else and #endif. For what it's worth if any of you need to write an interpreter for a programming language in some other context, I would recommend the use of readline, it seems quite good. Best Regards, Chris Beck P.S. For anyone interested, here is a link to my cross-compiled version of GNU history v 6.2.0, tested to work with my mingw32-compiled wesnoth. http://goo.gl/lFz44P?gdriveurl
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