How to run Cython examples in SageMathCell

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For what it's worth, I don't know why you're doing sys.path.append(directory_name), but you probably needn't do so. What does hello_sage.pyx have in it? You can also use %cython for directly compiling Cython code, but %runfile should effectively do the same if it's passed a path to a .pyx file.

Hi @Iguananaut thanks, I use sys.path.append() to be sure the remote python environment can find my files and libraries to be compiled in the temporary folder. Why it is not necessary?

"hello_sage.pyx" is a file containing: """ cdef extern from "hello.c": void hello_world()

def my_bridge_function(): hello_world() # This is the C function from hello.c """ as this link suggests. The path for "hello_sage.pyx", I suppose, is directory_name/Call_C_code, as indicated in "%runfile Call_C_code/hello_sage.pyx" and with the command "os.chdir(directory_name)" I'm sure my working folder is the temporary folder named "directory_name".

What is wrong? Thank you

FWIW you should be able to edit your question to add more details like the contents of the file.

I don't know what you mean by "the remote python environment". If you just want to run a single Python module it's not necessary to add its path to sys.path. sys.path only affects where modules are searched for when you use the import statement, wheres %runfile is already giving the path to a module directly.

This is like the difference in a shell when running a command by name like ls, as opposed to its full path /bin/ls. To run /bin/ls you don't need /bin on your PATH environment variable, but if you just run ls you do because the shell needs to know what paths to look in for a program called ls.

Hi @Iguananaut thank you for support, I try to describe better what I mean. I use sage only on the Internet using the free service SageMathCell. It is an online sagemath service.

Inside the zip folder "Call_C_code.zip" there are 3 files, one of them (text.txt) is a dummy text file I added for some tests, the other two files are the files of the example here. The two files for Cython test are: "hello_sage.pyx" and "hello_test.c".

Inside "hello_sage.pyx" there is the Cython code, while inside "hello_test.c" there is the C code. The content is, adapted on filenames, the same you find here.

Please can you run without problems the script in first post by using SageMathCell or not? I'm testing Cython features of the online service SageMathCell by following the simple example "How to call a C code (or a compiled library) from Sage?".

"hello_sage.pyx":

cdef extern from "Call_C_code/hello_test.c":
    void hello_world()

def my_bridge_function():
    hello_world() # This is the C function from hello_test.c

"hello_test.c":

#include <stdio.h>

void hello_world(){
    printf("Hello World\n");
}

Thanks