On Sat, Jun 16, 2018 at 12:46 AM Stephan Beal <sgb...@googlemail.com> wrote:
> i will write a longer response when i'm back on the PC, but short version: > > - refactoring to a lib is a huge effort. > ... > More details upcoming about that first point in the morning. > So... http://fossil.wanderinghorse.net/r/libfossil that's now effectively defunct, though, as i've been on medical leave for RSI most of the past 3.5 years and am currently on track to be forced into early retirement within the next couple of months. Several aspects of fossil make it very tedious (but not difficult, per se) to port to a library: 1) it uses a great deal of global state. That's simple enough to factor into a Context object, but... 2) it relies on a fail-fast-and-fail-loud allocator. Any allocation error will immediately (intentionally) crash the app. While that saves literally half (sometimes more) of code/error checking any place where memory is allocated (that's a lot of places), that pattern is unusable for libraries. Granted, allocation errors are rare, but every single C call which allocates has to check for failure or risk Undefined Behaviour. To simplify the vast majority of the implementation, Fossil does this checking in a single place and abort()s the app if an allocation fails. 3) Fossil effectively uses exit() to handle just about any type of non-allocation error. i.e. there's little library-friendly error handling in fossil. 4) Last but not least: Fossil implements a great many intricate algorithms which, if not ported 100% perfectly, could lead to all sorts of Grief, some of it difficult to track down. Such ports typically require 2x as much code, sometimes more, because of the addition of error checking and handling (as opposed to using abort() and exit()). libfossil had essentially all of the core-most functionality running (documented, too) when RSI knocked me out, and was mainly missing network-related functionality. It took, according to the timeline, about 16 months to get it to that point (noting that i also worked on other projects at the time, so that's not "16 months of effort"). My plan was to pick it back up when my RSI problems passed, but whether they will is now an open question. In the mean time, the SHA-related changes have made libfossil incompatible with fossil, meaning that it would be much more difficult to get it back up and running. i would be thrilled to see someone implement a library for fossil, but anyone doing so needs to understand, in advance, that it's a large undertaking. -- ----- stephan beal http://wanderinghorse.net/home/stephan/ "Freedom is sloppy. But since tyranny's the only guaranteed byproduct of those who insist on a perfect world, freedom will have to do." -- Bigby Wolf
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