Nim is a compiled, garbage-collected systems programming language which has an excellent productivity/performance ratio. Nim's design focuses on efficiency, expressiveness, elegance (in the order of priority).
<rayman22201> Nim maps exceptions to C++ exceptions when using the C++ backend, and those have proven to have acceptable overhead (They are actually very performant in modern compiler implementations). Using the C backend, they are mapped to crudely to long jumps IIRC... but I don't remember exactly. They do have worse performance in the C backend though.
<rayman22201> unwrapping is not as big of an issue because nim datatypes don't have most of the OOP garbage attached to a C++ class
<I_Right_I> rayman22201: Okay thanks for the insight!
<rayman22201> sorry I can't be more specific. It's not my area of expertise.
<rayman22201> fair enough. At least you know you have the option. another tool in the toolbox as they say :-)
I'm coming back to Nim/C binding exercise after a while, and I have never handled mapping a C array pointer type to Nim
How would I map
int *data; from C to Nim?
I looked in Nim forum but the solution there to use a
0..0 array with {.unchecked.} doesn't work on the latest devel. Ref: https://forum.nim-lang.org/t/567
The bigger picture is that I am exporting a Matlab code to C using Matlab and then trying to map that to Nim
a snippet of Matlab exported C header:
struct emxArray_int32_T
{
int *data;
int *size;
int allocatedSize;
int numDimensions;
boolean_T canFreeData;
};
typedef struct emxArray_int32_T emxArray_int32_T;
typedef struct {
emxArray_int32_T *data;
int len;
} struct0_T;
also I get warning for using pragma before generics
latest devel
ok, on devel it looks different: https://nim-lang.github.io/Nim/system.html#UncheckedArray
what does this mean? https://github.com/nim-lang/Nim/blob/devel/lib/system.nim#L294-L296
i.e. how do I use it in my code?
and in
struct emxArray_int32_T, I have pointers to two int arrays along with other "normal" types
btw
echo test2 doesn't work as $ isn't implemented for UncheckedArray
I don't know if that's intentional or an oversight
I'd have thought that that $ printed all values in the allocated space
<shashlick> well its an array of integers
but even
echo test2[] doesn't work
but this works, so good enough to proceed with my debug for now:
for i in 0 .. 3:
echo test2[i]
I got the Nim code to compile, but ending up with SIGSEGV .. Nim code: http://ix.io/1FlB
the code calls
mean_func_1 from compiled .so of Matlab exported .c
here's the mean_func_1 implementation in C: http://ix.io/1FlC
or maybe I'm reading it wrong. it doesn't quite say if the existence of a non-owning ref has that effect.
fixed Nim code: http://ix.io/1FlE
thanks for your help with UncheckedArray; that motivated me to try to solve this