CYTHON(1)

✨ CYTHON(1) ✨

okay bestie, sit DOWN, because this is the manual page for cython from User Commands and it's literally the moment your .pyx files get their glow-up 💅

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🌸 NAME 🌸

cython — compile Cython code (.pyx) into C so you can build a Python extension 🐍➡️🇨

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🦋 DESCRIPTION 🦋

okay so, here's the vibe. The usage line goes like this, exactly:

cython [-h] [-V] [-l] [-I INCLUDE_PATH] [-o OUTPUT_FILE] [-t]
       [-f] [-v]

       [-p] [--cleanup GENERATE_CLEANUP_CODE] [--cache] [-w
       WORKING_PATH] [--gdb] [--gdb-outdir GDB_OUTDIR] [-D] [-a]
       [--annotate-fullc] [--annotate-coverage ANNOTATE_COVERAGE_XML]
       [--line-directives] [-+] [--embed] [-2] [-3] [--3str] [--lenient]
       [--capi-reexport-cincludes] [--fast-fail] [-Werror] [-Wextra] [-X
       NAME=VALUE,...] [-E NAME=VALUE,...]  [--module-name MODULE_NAME]
       [-M] [--generate-shared SHARED_C_FILE_PATH] [--shared
       SHARED_UTILITY_QUALIFIED_NAME] [sources ...]

So what even IS this? Cython (https://cython.org/) is a compiler for code written in the Cython language. That's the whole thing. And plot twist: Cython is based on Pyrex by Greg Ewing 🫶 (shoutout to the ancestors, no cap).

👑 positional arguments:

• sources — the files you're feeding in, bestie. That's it, that's the list.

💖 options:

• -h, --help — shows this help message and dips. classic.
• -V, --version — Display version number of cython compiler ✨
• -l, --create-listing — Write error messages to a listing file 📝 (so you can read your mistakes in style)
• -I, --include-dir INCLUDE_PATH — Search for include files in named directory. and yes, you can stack them — multiple include directories are allowed 🎀
• -o, --output-file OUTPUT_FILE — Specify name of generated C file
• -t, --timestamps — Only compile newer source files (lazy-girl efficiency, we love her)
• -f, --force — Compile all source files, and it overrides implied -t 💀 no skipping allowed
• -v, --verbose — Be verbose, print file names on multiple compilation 🗣️
• -p, --embed-positions — If specified, the positions in Cython files of each function definition is embedded in its docstring.
• --cleanup GENERATE_CLEANUP_CODE — Release interned objects on python exit, for memory debugging. Level indicates aggressiveness, default 0 releases nothing.
• --cache — Enables Cython compilation cache. ⚡ (she remembers things so you don't have to)
• -w, --working WORKING_PATH — Sets the working directory for Cython (the directory modules are searched from)
• --gdb — Output debug information for cygdb 🐛
• --gdb-outdir GDB_OUTDIR — Specify gdb debug information output directory. Implies --gdb. (sneaky little chain reaction, iykyk)
• -D, --no-docstrings — Strip docstrings from the compiled module. bye bye little comments 😭
• -a, --annotate — Produce a colorized HTML version of the source. 🌈 pretty AND useful
• --annotate-fullc — Produce a colorized HTML version of the source which includes entire generated C/C++-code.
• --annotate-coverage ANNOTATE_COVERAGE_XML — Annotate and include coverage information from cov.xml.
• --line-directives — Produce #line directives pointing to the .pyx source
• -+, --cplus — Output a C++ rather than C file. ✨C++ girlies rise✨
• --embed — Generate a main() function that embeds the Python interpreter. Pass --embed=<method_name> for a name other than main().
• -2 — Compile based on Python-2 syntax and code semantics.
• -3 — Compile based on Python-3 syntax and code semantics.
• --3str — Compile based on Python-3 syntax and code semantics (same as -3 since Cython 3.1).
• --lenient — Change some compile time errors to runtime errors to improve Python compatibility 🫶 (she's being nice to you)
• --capi-reexport-cincludes — Add cincluded headers to any auto-generated header files.
• --fast-fail — Abort the compilation on the first error. no second chances, periodt 💀
• -Werror, --warning-errors — Make all warnings into errors. every warning is now a jumpscare 🙈
• -Wextra, --warning-extra — Enable extra warnings.
• -X, --directive NAME=VALUE,... — Overrides a compiler directive
• -E, --compile-time-env NAME=VALUE,... — Provides compile time env like DEF would do.
• --module-name MODULE_NAME — Fully qualified module name. If not given, is deduced from the import path if source file is in a package, or equals the filename otherwise.
• -M, --depfile — produce depfiles for the sources
• --generate-shared SHARED_C_FILE_PATH — Generates shared module with specified name.
• --shared SHARED_UTILITY_QUALIFIED_NAME — Imports utility code from shared module specified by fully qualified module name.

🧚 Environment variables:

• CYTHON_CACHE_DIR — the base directory containing Cython's caches. 🎀 that's the one, bestie, that's the whole list.

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real talk for one sec: this page is from Cython 3.1.6, dated March 2026, and it's filed under CYTHON(1) in the User Commands section. go forth and compile, my love 💜🦋✨