The Cross-Platform Cython/Python Compiler
We all know the beauties of Cython:
Writing C extensions is just as easy as Python
Almost any valid Python is valid Cython, as Cython is a super-set of Python
It has the readability of Python, but the speed of C
Minimal effort has to be taken in order to speed up some programs by two to four orders of magnitude
However, compiling is not always easy. There are a few places that disutils’ setup.py can get tripped up.
vcvarsall.bat not found error
gcc: undefined reference to…
Other errors basically referring to compiler not found
Cython may be almost as easy to write as Python, but sometimes nowhere near the level of easiness that it takes to run Python. This is where Cyther comes into play. Cyther is an attempt at a cross platform compiler that wields both the standard Cython compiler and gcc to make sure that these errors don’t happen.
How to use:
Cyther is extremely easy to use. One can call cytherize from the command line, or import cyther and call cyther.core from the module level.
from cyther import core core('example_file.pyx')
same can be done with:
$ cytherize example_file.pyx
And as expected, one can call $ cytherize -h for all the argument help they need. See below.
A few nifty examples:
Compile a Python file. This is the simplest usage of Cyther
Compile a Cython file while building the C files in-place (-l), and compiling only if the source file has been updated (-s)
core('example_file.pyx -s -l')
Run an infinite loop, watching the given file(s) for changes, and automatically compile them (-w) when detected
And don’t forget, this can also be done from the terminal!
$ cytherize example_file.py $ cytherize example_file.pyx -s -l $ cytherize example_file.pyx -w
The command line interface of the -w option
$ cytherize example_file.pyx -w cython -a -p -o X:\Cyther\__cythercache__\example_file.c X:\Cyther\example_file.pyx gcc -fPIC -shared -w -O3 -ID:\Python35\include -LD:\Python35\libs -o X:\Cyther\example_file.pyd X:\Cyther\__cythercache__\example_file.c -lpython35 Compiled the file ...<iterations:1, compiles:1, errors:0, polls:12>... Compiled the file ...<iterations:2, compiles:2, errors:0, polls:19>... Error compiling Cython file: ------------------------------------------------------------ ... def inverse_triangular(n): x = (sqrt(8 * n + 1) - 1) / 2 n = int(x) if x - n > 0: return Flse ^ ------------------------------------------------------------ example_file.pyx:15:19: undeclared name not builtin: Flse Cyther will wait for you to fix this error before it tries to compile again... ...<iterations:3, compiles:2, errors:1, polls:31>... Compiled the file ...<iterations:4, compiles:3, errors:1, polls:51>...
Compile these two files and pass in the Cython argument -l (_l) to the Cython compiler before using gcc
$ cytherize example_file.pyx another_file.py -l -w -cython _l
You can also write something like this to execute tests directly after the build procedure
# example_file.pyx from math import sqrt cdef int triangular(int n): cdef: double q int r q = (n * (n + 1)) / 2 r = int(q) return r def inverse_triangular(n): x = (sqrt(8 * n + 1) - 1) / 2 n = int(x) if x - n > 0: return False return int(x) ''' @Cyther a = ''.join([str(x) for x in range(10)]) print(a) '''
The @Cyther line tells Cyther that it should extract the code after it in the single quoted multi-line string and execute it if the build passed. One can also tell Cyther to time the @Cyther code, returning an IPython-esque timing message. Here are a few examples of how to use these features.
The wonderful -x option, and its output to stdout
$ cytherize example_file.pyx -x 0123456789
The -t option is also super helpful
$ cytherize example_file.pyx -t 10000 loops, best of 3: (2.94e-06) sec per loop
The help text of cytherize:
$ cytherize -h usage: cytherize.py [-h] [-c] [-p PRESET] [-s] [-o OUTPUT_NAME] [-i INCLUDE] [-l] [-w] [-e] [-x | -t] [-X | -T] [-cython CYTHON_ARGS [CYTHON_ARGS ...]] [-gcc GCC_ARGS [GCC_ARGS ...]] filenames [filenames ...] Auto compile and build .pyx or .py files in place. positional arguments: filenames The Cython source files optional arguments: -h, --help show this help message and exit -c, --concise Get cyther to NOT print what it is thinking. Only use if you like to live on the edge -p PRESET, --preset PRESET The preset options for using cython and gcc (ninja, beast, minimal, swift) -s, --timestamp If this flag is provided, cyther will not compile files that have a modifiedtime before that of your compiled .pyd or .so files -o OUTPUT_NAME, --output_name OUTPUT_NAME Change the name of the output file, default is basename plus .pyd -i INCLUDE, --include INCLUDE The names of the python modules that have an include library that needs to be passed to gcc -l, --local When not flagged, builds in __cythercache__, when flagged, it builds locally in the same directory -w, --watch When given, cyther will watch the directory with the 't' option implied and compile,when necessary, the files given -e, --error Raise a CytherError exception instead of printing out stderr when -w is not specified -x, --execute Run the @Cyther code in multi-line single quoted strings, and comments -t, --timeit Time the @Cyther code in multi-line single quoted strings, and comments -X A 'super flag' that implies these flags: '-x', '-s', '-p swift' -T A 'super flag' that implies these flags: '-t', '-s', '-p swift' -cython CYTHON_ARGS [CYTHON_ARGS ...] Arguments to pass to Cython -gcc GCC_ARGS [GCC_ARGS ...] Arguments to pass to gcc System: Python (D:\Python35\python.EXE): Version: 3.5 Operating System: Windows-10-10.0.10586-SP0 OS is Windows: True Default Output Extension: .pyd Installation Directory: D:\Python35 Cython (D:\Python35\Scripts\cython.EXE): Nothing Here Yet GCC (D:\MinGW\bin\gcc.EXE): Nothing Here Yet (Use '_' or '__' instead of '-' or '--' when passing args to gcc or Cython) (The '-x' and '-b' Boolean flags are mutually exclusive)
Assumptions Cyther makes about your system:
Cyther isn’t quite perfect yet, so all the incompatibilities and assumptions that Cyther makes are listed below. We strongly recommend that you look them over before even considering usage. In the near future I hope to make Cyther as polished as possible, and bring the list of assumptions listed below to zero.
Cython and gcc are both installed, and accessible from the terminal
Your Python version supports shutil.which
Your environment path variable is able to be found by shutil.which
‘distutils’ is able to find the Python runtime static library (usually libpythonXY.a or libpythonXY.so)
Windows will support gcc compiled C code
Hey you! Yes you. If you notice any bugs or peculiarities, please report them to our bug tracker, it will help us out a lot!
If you have any questions or concerns, or even any suggestions, don’t hesitate to email me at:
Happy compiling! - Nick
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