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A number of places in the code base (notably ceval.c and frameobject.c) rely on mapping variable names to indices in the frame "locals plus" array (AKA fast locals), and thus opargs. Currently the compiler indirectly encodes that information on the code object as the tuples co_varnames, co_cellvars, and co_freevars. At runtime the dependent code must calculate the proper mapping from those, which isn't ideal and impacts performance-sensitive sections. This is something we can easily address in the compiler instead. This change addresses the situation by replacing internal use of co_varnames, etc. with a single combined tuple of names in locals-plus order, along with a minimal array mapping each to its kind (local vs. cell vs. free). These two new PyCodeObject fields, co_fastlocalnames and co_fastllocalkinds, are not exposed to Python code for now, but co_varnames, etc. are still available with the same values as before (though computed lazily). Aside from the (mild) performance impact, there are a number of other benefits: * there's now a clear, direct relationship between locals-plus and variables * code that relies on the locals-plus-to-name mapping is simpler * marshaled code objects are smaller and serialize/de-serialize faster Also note that we can take this approach further by expanding the possible values in co_fastlocalkinds to include specific argument types (e.g. positional-only, kwargs). Doing so would allow further speed-ups in _PyEval_MakeFrameVector(), which is where args get unpacked into the locals-plus array. It would also allow us to shrink marshaled code objects even further. https://bugs.python.org/issue43693 |
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| data | ||
| distributing | ||
| distutils | ||
| extending | ||
| faq | ||
| howto | ||
| includes | ||
| install | ||
| installing | ||
| library | ||
| reference | ||
| tools | ||
| tutorial | ||
| using | ||
| whatsnew | ||
| about.rst | ||
| bugs.rst | ||
| conf.py | ||
| contents.rst | ||
| copyright.rst | ||
| glossary.rst | ||
| license.rst | ||
| make.bat | ||
| Makefile | ||
| README.rst | ||
| requirements.txt | ||
| runtime.txt | ||
Python Documentation README ~~~~~~~~~~~~~~~~~~~~~~~~~~~ This directory contains the reStructuredText (reST) sources to the Python documentation. You don't need to build them yourself, `prebuilt versions are available <https://docs.python.org/dev/download.html>`_. Documentation on authoring Python documentation, including information about both style and markup, is available in the "`Documenting Python <https://devguide.python.org/documenting/>`_" chapter of the developers guide. Building the docs ================= The documentation is built with several tools which are not included in this tree but are maintained separately and are available from `PyPI <https://pypi.org/>`_. * `Sphinx <https://pypi.org/project/Sphinx/>`_ * `blurb <https://pypi.org/project/blurb/>`_ * `python-docs-theme <https://pypi.org/project/python-docs-theme/>`_ The easiest way to install these tools is to create a virtual environment and install the tools into there. Using make ---------- To get started on UNIX, you can create a virtual environment with the command :: make venv That will install all the tools necessary to build the documentation. Assuming the virtual environment was created in the ``venv`` directory (the default; configurable with the VENVDIR variable), you can run the following command to build the HTML output files:: make html By default, if the virtual environment is not created, the Makefile will look for instances of sphinxbuild and blurb installed on your process PATH (configurable with the SPHINXBUILD and BLURB variables). On Windows, we try to emulate the Makefile as closely as possible with a ``make.bat`` file. If you need to specify the Python interpreter to use, set the PYTHON environment variable instead. Available make targets are: * "clean", which removes all build files. * "venv", which creates a virtual environment with all necessary tools installed. * "html", which builds standalone HTML files for offline viewing. * "htmlview", which re-uses the "html" builder, but then opens the main page in your default web browser. * "htmlhelp", which builds HTML files and a HTML Help project file usable to convert them into a single Compiled HTML (.chm) file -- these are popular under Microsoft Windows, but very handy on every platform. To create the CHM file, you need to run the Microsoft HTML Help Workshop over the generated project (.hhp) file. The make.bat script does this for you on Windows. * "latex", which builds LaTeX source files as input to "pdflatex" to produce PDF documents. * "text", which builds a plain text file for each source file. * "epub", which builds an EPUB document, suitable to be viewed on e-book readers. * "linkcheck", which checks all external references to see whether they are broken, redirected or malformed, and outputs this information to stdout as well as a plain-text (.txt) file. * "changes", which builds an overview over all versionadded/versionchanged/ deprecated items in the current version. This is meant as a help for the writer of the "What's New" document. * "coverage", which builds a coverage overview for standard library modules and C API. * "pydoc-topics", which builds a Python module containing a dictionary with plain text documentation for the labels defined in `tools/pyspecific.py` -- pydoc needs these to show topic and keyword help. * "suspicious", which checks the parsed markup for text that looks like malformed and thus unconverted reST. * "check", which checks for frequent markup errors. * "serve", which serves the build/html directory on port 8000. * "dist", (Unix only) which creates distributable archives of HTML, text, PDF, and EPUB builds. Without make ------------ First, install the tool dependencies from PyPI. Then, from the ``Doc`` directory, run :: sphinx-build -b<builder> . build/<builder> where ``<builder>`` is one of html, text, latex, or htmlhelp (for explanations see the make targets above). Deprecation header ================== You can define the ``outdated`` variable in ``html_context`` to show a red banner on each page redirecting to the "latest" version. The link points to the same page on ``/3/``, sadly for the moment the language is lost during the process. Contributing ============ Bugs in the content should be reported to the `Python bug tracker <https://bugs.python.org>`_. Bugs in the toolset should be reported to the tools themselves. You can also send a mail to the Python Documentation Team at docs@python.org, and we will process your request as soon as possible. If you want to help the Documentation Team, you are always welcome. Just send a mail to docs@python.org.