solvespace VS cl-ppcre

Can second this!

However, I would recommend https://solvespace.com! It hits a sweet spot between features vs complexity/learning effort.

We use rebase on solvespace, along with sensible squashing so most commits along master are pretty self contained. You can see the clean history here:

https://github.com/solvespace/solvespace/commits/master/

I changed a behavior to the "more standard" one because it felt obviously right. This was a 3 line change. But the was enough backlash right there in the pull request. So I spent a couple hours remembering how to add a configuration option to keep the old way for those guys:

https://github.com/solvespace/solvespace/pull/1425

> If you like Linkage, you might also like Solvespace.

No, I mean Brent Curry's Linkage[1] bicycle design software, not David Rector's Linkage Mechanism Designer and Simulator[2].

You should read Wikipedia article.[0]

N.B. About SolveSpace, as I'm its experienced user[youtube,patreon], I may say next: yes, it could be used for bike mockup, as any other CAD, but it still has a lot of limitations and even does not export correct STEP files yet[3], and in FreeCAD such STEP could fixed only partially.[video]

So, for serious 3D CAD work I highly recommend use FreeCAD (and LibreCAD for 2D CAD work) instead of SolveSpace, and use SolveSpace only as a helper tool like a calc or as a notepad for noting ideas.

About Linkage Mechanism Designer and Simulator, it is only useful for planar (2D) kinematics analyze, and if You are looking an alternative for it take a look on Pyslvs[4], that is in part based on SolveSpace's solver.

[0] https://en.wikipedia.org/wiki/rattleCAD#History

[1] https://bikechecker.com/

[2] https://blog.rectorsquid.com/linkage-mechanism-designer-and-...

[3] https://github.com/solvespace/solvespace/issues/206

[4] https://github.com/KmolYuan/Pyslvs-UI

[video] https://www.youtube.com/watch?v=F3LJMeqUDrU

[youtube] https://www.youtube.com/@appsoft

[patreon] https://patreon.com/app4soft

C++ this file covers all the math for working with NURBS curves and surfaces:

https://github.com/solvespace/solvespace/blob/master/src/srf...

There is a lot more in other files - triangulation, booleans, creation - but the core math functions are there in very readable form.

>> Maybe somebody has statistical survey of how much of the existing deployed CPU core count is typically used?

My guess is very few cores are used on average. I did some testing with Solvespace to see which build options contributed most to performance:

https://github.com/solvespace/solvespace/issues/972

Obviously using OpenMP for multi-core was the big win. But what's not shown is that in typical usage (not the test I ran) if you're dragging some geometry around it will use all cores (in my case 4 cores / 8 threads) at about 50 percent utilization. That percentage probably drops as more cores are thrown at it due to Amdahl's Law. In other words, throwing double the cores at it will give a good boost to a lot of code that is already taking less than half the time (wall clock time, not CPU time).

We added OpenMP to a number of functions for significant performance gains. And in fact, any remining single-thread operation that gets the parallel treatment is likely to have a significant impact on overall performance since that is where most of the time is spent now. At this point we're more focused on features and bugs.

Algorithmic improvements are possible and I'd like to do those in the future, but they are much harder to do than sprinkling some #pragmas around critical loops. That will improve the scalability though, where multithreading really did not.

I've never used cl-ppcre myself, but its docs[1] claim that it provides compile-time regexes:

> CL-PPCRE uses compiler macros to pre-compile scanners at load time if possible. This happens if the compiler can determine that the regular expression (no matter if it's a string or an S-expression) is constant at compile time and is intended to save the time for creating scanners at execution time (probably creating the same scanner over and over in a loop).

[1]: https://edicl.github.io/cl-ppcre/

A few weeks back Xach recommended cl-ppcre which i found educational.

For simple string processing, there are some functions in the language, that you can find listed here (for string-specific functions) and here (for more generic sequence-handling functions). For anything involving regular expressions, cl-ppcre is the way, in particular the split and register-groups-bind functions.

I must have a serious bug in my writing about this, because this was never about regex engines -- it's about literals and domain-specific sublanguages in general. Composing DSL programs by string concatenation is such a famous source of security bugs you see it in top-10 lists. I linked to the very similar example of a PEG parsing DSL.

But any regex engine that can work with a parse tree shows the same principle, e.g. https://edicl.github.io/cl-ppcre/#create-scanner2

Take a look at - https://github.com/edicl/cl-ppcre

And here's what I believe represents the reality of the situation... Stas was indeed tired of ASDF's changes. Now the nature of what changes to make is a matter of judgement of course, but in this case (I'm thinking of SBCL's bug report request to update ASDF: https://bugs.launchpad.net/sbcl/+bug/1826074), it would be a different matter altogether if the discussion was centered on how best to make the new ASDF work with SBCL, but the thread reads to me like a man who had to put up with too much breakage for the upteenth time. Now, if (for the sake of argument :D) the change was of the necessary kind -- think hardware changes or security issues -- I can still see myself feeling wronged, it's human to do so. Because I don't trust ASDF anymore or I feel as if they (or other people at each step of the process) have not shared enough of the burden. But from the discussions I have read (https://github.com/edicl/cl-ppcre/pull/30) what the ASDF maintainers want to change does not seem unreasonable and they are willing to share the burden. But let us say it's truly a 50/50 deadlock. Well then Linus is right, show us the code, who dares wins. And Stas certainly has enough on his plate. But that's why we must cooperate. You don't have to be a diplomat to know the difference when two people want to work together and when one party wants out. And this setting makes more sense when you read (https://bugs.launchpad.net/sbcl/+bug/1823442) where Stas honestly states he wants nothing more to do with ASDF. I don't think it's unreasonable to surmise there's a bit more going on here than plainly technical issues.

Could you just direct me to some existing discussions, in order to save time? I already read this one.

I plan to use the regular expressions with a cl-ppcre wrapper, also emulating various clojure regular expression operations. Similar to re21, which doesn't quite support the operations in the way I'd like (or match the clojure operations), and whose regular expression literal syntax is "#//".