Testing Ruby VALUES in C-extension.

tt_su

I have a nested ruby array of points curves. The points are coming from a getter-method-call in a Ruby-class. The @points can be of vary length.
The problem is that RARRAY(curve_rbPoints)->len always gives the same length, so the code fails..
Is it because I'm hoisting the variable ?
I just found this bug so havent tested much yet..

~~NOTE: I should mention it get's the correct length 1st time round.~~
edit: nope.

That only works with older Ruby I think, 1.8.6 or earlier. After that they changed the data structure so you should use the RARRAY_LEN macro. That macro doesn't exist on early Ruby so I conditionally define it:

#ifndef RARRAY_LEN
#define RARRAY_LEN(x) (RARRAY(x)->len)
#endif

https://bitbucket.org/thomthom/tt-library-2/src/24f6daa97b4ed67836d67ad4ac2f2c2806ca2a6e/Ruby%20C%20Extensions/Bezier/TT_Geom_Bezier.c?at=Version%202.9#cl-14

When you look up info on Ruby C Extension programming make sure you check the date of the source. And refer to a recent version of README.EXT.

I also find a lot of clues in "Ruby MRI identifier search": http://rxr.whitequark.org/mri/ident

jolran

Ahhh. A solution perhaps
I'm running Sketchup 2013 in debug mode. So it should be running Ruby 1.8.6 though ?

This has been a very annoying problem to solve. I'm clueless.

There's no error but irratic behavior with wrong values which makes it hard to track.

I was thinking it had something to do with me calling instance method from a class
sort of thing. The "curve" is an instance from a class I created and not a Sketchup curve, but I assume you got that part.

I suppose I could make the Ruby array an accessor and then use instance var get, but I rather not.

Will try your code when I get to my workstation later.

Thanks!

tt_su

I don't see anything immediately wrong. But have you checked and validated the input data?
Feels like there's some issue not located to that small snippet you have. If a complex case fails, try to reproduce in a small standalone case.

Btw, rb_intern returns ID, not VALUE. At least in Ruby 1.8 they are typedef of the same, but you cannot be sure of that and should make sure when a function use ID vs VALUE.

tt_su

Also, you're using out C++ example? Then you don't have to declare all variables in advance. That's very old C syntax. Even newer C syntax allow you to declare variables when you need them.

jolran

I am doing a C++ extension, yes.

@unknownuser said:

rb_intern returns ID, not VALUE

Well that changes things. That could be it. Will test that in various combinations and report back.

So would the syntaxrb_funcall(rb_intern("get_points")etc... be better then instead of storing it ?

@unknownuser said:

try to reproduce in a small standalone case.

I have created a smallish testcase. Although I needed some classes for that.
So the code become over 500 lines.
I run that code in Alex ruby code editor while debug. Don't know if that can affect the scope of class or anything.

And I have tested the data before sending in to c-extension, it's alright in Ruby.

The C++ code may very well have logic errors I havent found yet. So I have to scan that through again. It looks like this is the main problem though, since I'm dependent of array length for next iterations. When all the arrays(curves) have same length code is working.

@unknownuser said:

That's very old C syntax. Even newer C syntax allow you to declare variables when you need them.

I couldent tell whats proper syntax or not, yet. That does sound easier.
Does that go for loops/iterators as well?

tt_su

@jolran said:

@unknownuser said:

rb_intern returns ID, not VALUE

Well that changes things. That could be it. Will test that in various combinations and report back.

Don't think it does any harm in Ruby 1.8 and 2.0 as both happen to be typedef of unsigned long - the compiler won't know the difference. So I don't think that is your issue here.
But if the Ruby C API changes what types they map to you will get trouble.

@jolran said:

I couldent tell whats proper syntax or not, yet. That does sound easier.
Does that go for loops/iterators as well?

[/quote]
Best practices usually states to declare variables right before you need them and scope them as appropriate.
I'm not quite sure what you are asking for about loops and iterators though.

jolran

I meant hoisting variables before running loops. Speeding up the loops by not declaring them inside the loop.

Changing to rb_funcall(curve, rb_intern("get_points"), 0); made no difference, so I will try that other macro you mentioned. Otherwise there must be some hole in my logic elsewhere..

PS: I havent come to best practices part yet

Thanks for the help.

jolran

Well well. How dumb can one get seriously

Have been copying and pasting in code from Notepad++ to sketchup ruby code editor.
Totally unfocused on that part..
At some point I must have pushed ctrl v instead of ctrl c, so I not noingly had duplicate code.

Off course I wasent editing the first part that was sent in to Visual studio for step over.

Hehum, thanks for the help Thomthom. All is not lost. You have provided some good information for the rest of us and I learned some new stuff

tt_su

@jolran said:

I meant hoisting variables before running loops. Speeding up the loops by not declaring them inside the loop.

That's a Ruby world optimization - because creating Ruby objects are expensive.
Not the same in C++.

So now you're getting the correct array size?

jolran

@unknownuser said:

That's a Ruby world optimization - because creating Ruby objects are expensive.
Not the same in C++.

Ok understood. It's quite wierd comming from Ruby to C++.

@unknownuser said:

So now you're getting the correct array size?

Yes. And the code work's as I wanted to So far anyway. Really fast.
I included your MACRO just to be safe. The code worked compiled in SU8.

I imagine I could even make it faster refactoring it. But.. Most importantly I want it to be proper, so I try to follow your advice and read up on best practices before I move on.

On another different subject while we are at it. Probably should start a new topic, but it doesent fell improper to ask here as well.

Can we use Windows forms or WXwidgets(not WX-rubyversion) or other GUI toolkit with c++ in Sketchup ?
I've seen discussion about it, but it was long time ago and relevant to only Ruby.

I've seen examples where they hook up MFC as resource to win32 projects. Also read here somewhere it can be problematic to hook that up to Sketchup window, since windialogs are under the desktop(?)
Anyway, not an substitute for webdialogs, just could be handy for some simpler dialogs using visual studio dialog editor.

tt_su

I can't speak for WXwidgets, not familiar with it. Though I seem to recall some issues where they changed the order the window hierarchy - but maybe that was just the Ruby wrapper, I don't know.

But in general you can use whatever C/C++ lib you want. Native dialogs, knock yourself out. I haven't done so myself yet, but I wanted to try out a simple hello world window once.
I have done some code that calls the system folder picking dialogs though. Works very well.

jolran

@unknownuser said:

I can't speak for WXwidgets, not familiar with it. Though I seem to recall some issues where they changed the order the window hierarchy - but maybe that was just the Ruby wrapper, I don't know.

I think it was the Ruby wrapper that was causing problems.
The posts touching the subjects are very old, as mentioned..

@unknownuser said:

But in general you can use whatever C/C++ lib you want. Native dialogs, knock yourself out. I haven't done so myself yet, but I wanted to try out a simple hello world window once.
I have done some code that calls the system folder picking dialogs though. Works very well.

I thought it was a no go on that! I'll peek around a little then.
Report back if I find something exiting.

Thanks

Garry K

I've just read all of this - very helpful and interesting.

Years ago I had a project that had to work with 3 compilers, CE, Visual C++ and C++Builder and I had a single code base.

I ended up learning new optimization procedures which when used right from the start created no extra work. For CE and risc processors you must design data structures that are memory aligned. This not only runs fine on cisc - it is automatically optimized. The key bit here is that if a 4 byte int crosses a memory boundary then cisc does 2 fetches and stitches it together, risc simply crashes.

I created a tList object that works with all 3 compilers. You can treat a tList as an array or a hash or a set. You can pass in objects and perform binary tree searches on any member of the object by simply passing it a function pointer to your own custom compare function. This is useful when you want many sort combinations on a single collection. This is a quicksort implementation.

How the tList works is it is essentially an array of pointers. The array is in contiguous memory. The array grows in a very specific way and is moved if you run out of free contiguous memory. When the tList object is first created you can provide an initial number of elements that you want thus avoiding repeated calls to malloc and avoiding moving memory. When sorting just the list of pointers sort - the collected objects stay where they are.

Here is a compare function that sorts on 2 fields. If first field is a tie then sort on second field
The void pointer is cast as the type of object that you collect in the tList.
fIndex is 1 or -1 which changes the sort from ascending to descending


int __fastcall CompareCabsCabinet( void * Item1, void * Item2 )
{
	int res;

	tCab *v1 = ( tCab *) Item1;
	tCab *v2 = ( tCab *) Item2;

	res = strcmp( v1->Description.c_str(), v2->Description.c_str() );

	if ( res == 0 )
		res = v1->CabNumber - v2->CabNumber;

	return fIndex * res;
}
//---------------------------------------------------------------------------

When I wrote a GIS rendering engine I used a tList for all the points. I added a quad tree for static map data and an rtree for dynamic gps points.

I ended up with virtually instant renderings with a million points.

tt_su

Came across this article today: http://silverhammermba.github.io/emberb/c/#exceptions

Nice little overview over the Ruby C API.

Garry K

good article - it has already answered some of my questions.

tt_su

It explains the important parts better than the Ruby C API readme:
https://github.com/ruby/ruby/blob/trunk/README.EXT

jiminy-billy-bob

I just came accross an issue you guys should know about (if you don't already) : We can't pass more than 15 arguments in a single function from ruby to C++.

Garry K

It looks like I'll have to use the visual studio compiler for c extensions in sketchup.
There is an MS specific config file and no other counterparts for borland etc.

ThirdParty\include\ruby\2.0\win32\i386-mswin32_100\ruby\config.h

tt_su

@jiminy-billy-bob said:

I just came accross an issue you guys should know about (if you don't already) : We can't pass more than 15 arguments in a single function from ruby to C++.

You actually hit that limit?

tt_su

@garry k said:

It looks like I'll have to use the visual studio compiler for c extensions in sketchup.
There is an MS specific config file and no other counterparts for borland etc.

ThirdParty\include\ruby\2.0\win32\i386-mswin32_100\ruby\config.h

For the examples we provided projects only for Visual Studio on Windows and Xcode on OSX. If you want to compile with another compiler you are free to do so - but we don't provide examples for all compilers.