Please, note that Cxx.jl only works (out of the box) currently with Julia 1.1.x to 1.3.x, i.e. with no currently supported Julia, while those versions can still be downloaded at Julialang.org. For support of newer Julia versions see CxxWrap.jl.
The Julia C++ Foreign Function Interface (FFI) and REPL.
Now, this package provides an out-of-box installation experience on 64-bit Linux, macOS and Windows.
pkg> add Cxx
Note that Windows support is still in its early stage, so feel free to submit feedback in the issue tracker.
If you're working on macOS Sonoma, you might need to fix this manually.
In addition to the system requirements to build julia itself, the following are required:
- Debian/Ubuntu:
libedit-dev,libncurses5-dev - RedHat/CentOS:
libedit-devel
Launch Julia (version 1.0 or later), and in the terminal type
pkg> build CxxThe main interface provided by Cxx.jl is the @cxx macro. It supports two main usages:
- Static function call @cxx mynamespace::func(args...)
- Membercall (where m is a CppPtr, CppRef or CppValue) @cxx m->foo(args...)
To embed C++ functions in Julia, there are two main approaches:
# Using @cxx (e.g.):
cxx""" void cppfunction(args){ . . .} """ => @cxx cppfunction(args)
# Using icxx (e.g.):
julia_function (args) icxx""" *code here* """ endThis package contains an experimental C++ REPL feature. Using the package
will automatically add a new pane to your REPL that is accessible by pressing the
< key.
# include headers
julia> using Cxx
julia> cxx""" #include<iostream> """
# Declare the function
julia> cxx"""
void mycppfunction() {
int z = 0;
int y = 5;
int x = 10;
z = x*y + 2;
std::cout << "The number is " << z << std::endl;
}
"""
# Convert C++ to Julia function
julia> julia_function() = @cxx mycppfunction()
julia_function (generic function with 1 method)
# Run the function
julia> julia_function()
The number is 52julia> jnum = 10
10
julia> cxx"""
void printme(int x) {
std::cout << x << std::endl;
}
"""
julia> @cxx printme(jnum)
10julia> cxx"""
void printme(const char *name) {
// const char* => std::string
std::string sname = name;
// print it out
std::cout << sname << std::endl;
}
"""
julia> @cxx printme(pointer("John"))
Johnjulia> cxx"""
void testJuliaPrint() {
$:(println("\nTo end this test, press any key")::Nothing);
}
"""
julia> @cxx testJuliaPrint()
To end this test, press any keyfunction playing()
for i = 1:5
icxx"""
int tellme;
std::cout<< "Please enter a number: " << std::endl;
std::cin >> tellme;
std::cout<< "\nYour number is "<< tellme << "\n" <<std::endl;
"""
end
end
playing();julia> cxx"""
class Klassy {
public:
enum Foo { Bar, Baz };
static Foo exec(Foo x) { return x; }
};
"""
# Access enum
julia> @cxx Klassy::Bar
CppEnum{Symbol("Klassy::Foo")}(0)
# Pass enum as an argument
julia> @cxx Klassy::exec(@cxx(Klassy::Baz))
CppEnum{Symbol("Klassy::Foo")}(1)julia> using Cxx
julia> cxx"""#include <iostream>
class Hello
{
public:
void hello_world(const char *now){
std::string snow = now;
std::cout << "Hello World! Now is " << snow << std::endl;
}
};"""
julia> hello_class = @cxxnew Hello()
julia> tstamp = string(Dates.now())
julia> @cxx hello_class -> hello_world(pointer(tstamp))
Hello World! Now is 2015-06-19T11:20:31
ArrayMaker.h
#ifndef ARRAYMAKER_H
#define ARRAYMAKER_H
class ArrayMaker
{
private:
int iNumber;
float fNumber;
float* fArr;
public:
ArrayMaker(int, float);
float* fillArr();
};
#endifArrayMaker.cpp
#include "ArrayMaker.h"
#include <iostream>
using namespace std;
ArrayMaker::ArrayMaker(int iNum, float fNum) {
cout << "Got arguments: " << iNum << ", and " << fNum << endl;
iNumber = iNum;
fNumber = fNum;
fArr = new float[iNumber];
}
float* ArrayMaker::fillArr() {
cout << "Filling the array" << endl;
for (int i=0; i < iNumber; i++) {
fArr[i] = fNumber;
fNumber *= 2;
}
return fArr;
}Compiling into shared library
>> g++ -shared -fPIC ArrayMaker.cpp -o libArrayMaker.so
Using in Julia
julia> using Cxx
julia> using Libdl
# Importing shared library and header file
julia> const path_to_lib = pwd()
julia> addHeaderDir(path_to_lib, kind=C_System)
julia> Libdl.dlopen(path_to_lib * "/libArrayMaker.so", Libdl.RTLD_GLOBAL)
Ptr{Cvoid} @0x000000000728e6d0
julia> cxxinclude("ArrayMaker.h")
# Creating class object
julia> maker = @cxxnew ArrayMaker(5, 2.0)
Got arguments: 5, and 2
Cxx.CppPtr{Cxx.CppValue{Cxx.CppBaseType{:ArrayMaker},(false,false,false)},(false,false,false)}(Ptr{Cvoid} @0x00000000060ab570)
julia> arr = @cxx maker->fillArr()
Filling the array
julia> unsafe_wrap(Array, arr, 5)
5-element Array{Float32,1}:
2.0
4.0
8.0
16.0
32.0As of now Cxx.jl does not allow redefinition of a function. In order to allow defining the same function multiple times the current compiler instance can be replaced by typing
__current_compiler__ = Cxx.new_clang_instance()