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paulrosspaulross
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Fairly mature and reviewed. Lets release!
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‎.gitignore

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doc/sphinx/build/*
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src/build/*
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*.so
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PythonExtensionPatterns/*

‎.project

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<?xml version="1.0" encoding="UTF-8"?>
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<projectDescription>
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<name>PythonExtensionPatterns</name>
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<comment></comment>
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<projects>
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</projects>
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<buildSpec>
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<buildCommand>
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<name>org.python.pydev.PyDevBuilder</name>
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<arguments>
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</arguments>
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</buildCommand>
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</buildSpec>
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<natures>
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<nature>org.python.pydev.pythonNature</nature>
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</natures>
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</projectDescription>

‎.pydevproject

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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<?eclipse-pydev version="1.0"?><pydev_project>
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<pydev_pathproperty name="org.python.pydev.PROJECT_SOURCE_PATH">
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<path>/${PROJECT_DIR_NAME}/src</path>
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</pydev_pathproperty>
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<pydev_property name="org.python.pydev.PYTHON_PROJECT_VERSION">python 3.0</pydev_property>
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<pydev_property name="org.python.pydev.PYTHON_PROJECT_INTERPRETER">python3.3</pydev_property>
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</pydev_project>

‎PythonExtensionPatterns.bbprojectd/Scratchpad.txt

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‎PythonExtensionPatterns.bbprojectd/Unix Worksheet.worksheet

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‎doc/sphinx/Makefile

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# Makefile for Sphinx documentation
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#
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# You can set these variables from the command line.
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SPHINXOPTS =
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SPHINXBUILD = sphinx-build
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PAPER =
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BUILDDIR = build
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# User-friendly check for sphinx-build
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ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
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$(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD environment variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don't have Sphinx installed, grab it from http://sphinx-doc.org/)
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endif
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# Internal variables.
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PAPEROPT_a4 = -D latex_paper_size=a4
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PAPEROPT_letter = -D latex_paper_size=letter
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ALLSPHINXOPTS = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) source
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# the i18n builder cannot share the environment and doctrees with the others
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I18NSPHINXOPTS = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) source
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.PHONY: help clean html dirhtml singlehtml pickle json htmlhelp qthelp devhelp epub latex latexpdf text man changes linkcheck doctest gettext
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help:
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@echo "Please use \`make <target>' where <target> is one of"
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@echo " html to make standalone HTML files"
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@echo " dirhtml to make HTML files named index.html in directories"
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@echo " singlehtml to make a single large HTML file"
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@echo " pickle to make pickle files"
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@echo " json to make JSON files"
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@echo " htmlhelp to make HTML files and a HTML help project"
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@echo " qthelp to make HTML files and a qthelp project"
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@echo " devhelp to make HTML files and a Devhelp project"
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@echo " epub to make an epub"
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@echo " latex to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
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@echo " latexpdf to make LaTeX files and run them through pdflatex"
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@echo " latexpdfja to make LaTeX files and run them through platex/dvipdfmx"
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@echo " text to make text files"
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@echo " man to make manual pages"
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@echo " texinfo to make Texinfo files"
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@echo " info to make Texinfo files and run them through makeinfo"
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@echo " gettext to make PO message catalogs"
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@echo " changes to make an overview of all changed/added/deprecated items"
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@echo " xml to make Docutils-native XML files"
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@echo " pseudoxml to make pseudoxml-XML files for display purposes"
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@echo " linkcheck to check all external links for integrity"
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@echo " doctest to run all doctests embedded in the documentation (if enabled)"
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clean:
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rm -rf $(BUILDDIR)/*
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html:
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$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
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@echo
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@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
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dirhtml:
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$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
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@echo
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@echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml."
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singlehtml:
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$(SPHINXBUILD) -b singlehtml $(ALLSPHINXOPTS) $(BUILDDIR)/singlehtml
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@echo
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@echo "Build finished. The HTML page is in $(BUILDDIR)/singlehtml."
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pickle:
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$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle
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@echo
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@echo "Build finished; now you can process the pickle files."
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json:
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$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json
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@echo
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@echo "Build finished; now you can process the JSON files."
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htmlhelp:
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$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
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@echo
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@echo "Build finished; now you can run HTML Help Workshop with the" \
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".hhp project file in $(BUILDDIR)/htmlhelp."
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qthelp:
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$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp
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@echo
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@echo "Build finished; now you can run "qcollectiongenerator" with the" \
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".qhcp project file in $(BUILDDIR)/qthelp, like this:"
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@echo "# qcollectiongenerator $(BUILDDIR)/qthelp/PythonExtensionPatterns.qhcp"
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@echo "To view the help file:"
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@echo "# assistant -collectionFile $(BUILDDIR)/qthelp/PythonExtensionPatterns.qhc"
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devhelp:
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$(SPHINXBUILD) -b devhelp $(ALLSPHINXOPTS) $(BUILDDIR)/devhelp
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@echo
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@echo "Build finished."
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@echo "To view the help file:"
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@echo "# mkdir -p $$HOME/.local/share/devhelp/PythonExtensionPatterns"
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@echo "# ln -s $(BUILDDIR)/devhelp $$HOME/.local/share/devhelp/PythonExtensionPatterns"
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@echo "# devhelp"
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epub:
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$(SPHINXBUILD) -b epub $(ALLSPHINXOPTS) $(BUILDDIR)/epub
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@echo
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@echo "Build finished. The epub file is in $(BUILDDIR)/epub."
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latex:
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$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
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@echo
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@echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex."
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@echo "Run \`make' in that directory to run these through (pdf)latex" \
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"(use \`make latexpdf' here to do that automatically)."
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latexpdf:
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$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
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@echo "Running LaTeX files through pdflatex..."
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$(MAKE) -C $(BUILDDIR)/latex all-pdf
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@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
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latexpdfja:
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$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
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@echo "Running LaTeX files through platex and dvipdfmx..."
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$(MAKE) -C $(BUILDDIR)/latex all-pdf-ja
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@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
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text:
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$(SPHINXBUILD) -b text $(ALLSPHINXOPTS) $(BUILDDIR)/text
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@echo
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@echo "Build finished. The text files are in $(BUILDDIR)/text."
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man:
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$(SPHINXBUILD) -b man $(ALLSPHINXOPTS) $(BUILDDIR)/man
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@echo
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@echo "Build finished. The manual pages are in $(BUILDDIR)/man."
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texinfo:
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$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
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@echo
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@echo "Build finished. The Texinfo files are in $(BUILDDIR)/texinfo."
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@echo "Run \`make' in that directory to run these through makeinfo" \
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"(use \`make info' here to do that automatically)."
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info:
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$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
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@echo "Running Texinfo files through makeinfo..."
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make -C $(BUILDDIR)/texinfo info
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@echo "makeinfo finished; the Info files are in $(BUILDDIR)/texinfo."
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gettext:
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$(SPHINXBUILD) -b gettext $(I18NSPHINXOPTS) $(BUILDDIR)/locale
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@echo
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@echo "Build finished. The message catalogs are in $(BUILDDIR)/locale."
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changes:
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$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes
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@echo
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@echo "The overview file is in $(BUILDDIR)/changes."
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linkcheck:
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$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck
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@echo
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@echo "Link check complete; look for any errors in the above output " \
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"or in $(BUILDDIR)/linkcheck/output.txt."
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doctest:
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$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
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@echo "Testing of doctests in the sources finished, look at the " \
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"results in $(BUILDDIR)/doctest/output.txt."
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xml:
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$(SPHINXBUILD) -b xml $(ALLSPHINXOPTS) $(BUILDDIR)/xml
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@echo
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@echo "Build finished. The XML files are in $(BUILDDIR)/xml."
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pseudoxml:
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$(SPHINXBUILD) -b pseudoxml $(ALLSPHINXOPTS) $(BUILDDIR)/pseudoxml
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@echo
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@echo "Build finished. The pseudo-XML files are in $(BUILDDIR)/pseudoxml."

‎doc/sphinx/source/canonical_function.rst

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.. toctree::
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:maxdepth: 3
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===========================================
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A Pythonic Coding Pattern for C Functions
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===========================================
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To avoid all the errors we have seen it is useful to have a C coding pattern for handling ``PyObjects`` that does the following:
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* No early returns and a single place for clean up code.
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* Borrowed references incref'd and decref'd correctly.
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* No stale Exception from previous execution path.
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* Exceptions set and tested.
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* NULL is returned when an exception is set.
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* Non-NULL is returned when no exception is set.
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The basic pattern in C is similar to Python's try/except/finally pattern:
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.. code-block:: c
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try:
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/* Do fabulous stuff here. */
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except:
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/* Handle every abnormal condition and clean up. */
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finally:
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/* Clean up under normal conditions and return an appropriate value. */
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Firstly we set any local ``PyObject`` (s) and the return value to ``NULL``:
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.. code-block:: c
33+
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static PyObject *function(PyObject *arg_1) {
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PyObject *obj_a = NULL;
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PyObject *ret = NULL;
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Then we have a little bit of Pythonic C - this can be omitted:
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40+
.. code-block:: c
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goto try; /* Pythonic 'C' ;-) */
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try:
44+
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Check that there are no lingering Exceptions:
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.. code-block:: c
48+
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assert(! PyErr_Occurred());
50+
51+
An alternative check for no lingering Exceptions:
52+
53+
.. code-block:: c
54+
55+
if(PyErr_Occurred()) {
56+
goto except;
57+
}
58+
59+
Now we assume that any argument is a "Borrowed" reference so we increment it (we need a matching ``Py_DECREF`` before function exit, see below). The first pattern assumes a non-NULL argument.
60+
61+
.. code-block:: c
62+
63+
assert(arg_1);
64+
Py_INCREF(arg_1);
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66+
If you are willing to accept NULL arguments then this pattern would be more suitable:
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.. code-block:: c
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70+
if (arg_1) {
71+
Py_INCREF(arg_1);
72+
}
73+
74+
Of course the same test must be used when calling ``Py_DECFREF``, or just use ``Py_XDECREF``.
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76+
Now we create any local objects, if they are "Borrowed" references we need to incref them. With any abnormal behaviour we do a local jump straight to the cleanup code.
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.. code-block:: c
79+
80+
/* Local object creation. */
81+
/* obj_a = ...; */
82+
if (! obj_a) {
83+
PyErr_SetString(PyExc_ValueError, "Ooops.");
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goto except;
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}
86+
/* If obj_a is a borrowed reference rather than a new reference. */
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Py_INCREF(obj_a);
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89+
Create the return value and deal with abnormal behaviour in the same way:
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.. code-block:: c
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93+
/* More of your code to do stuff with arg_1 and obj_a. */
94+
/* Return object creation, ret should be a new reference otherwise you are in trouble. */
95+
/* ret = ...; */
96+
if (! ret) {
97+
PyErr_SetString(PyExc_ValueError, "Ooops again.");
98+
goto except;
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}
100+
101+
You might want to check the contents of the return value here. On error jump to ``except:`` otherwise jump to ``finally:``.
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.. code-block:: c
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/* Any return value checking here. */
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/* If success then check exception is clear,
108+
* then goto finally; with non-NULL return value. */
109+
assert(! PyErr_Occurred());
110+
assert(ret);
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goto finally;
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This is the except block where we cleanup any local objects and set the return value to NULL.
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.. code-block:: c
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except:
118+
/* Failure so Py_XDECREF the return value here. */
119+
Py_XDECREF(ret);
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/* Check a Python error is set somewhere above. */
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assert(PyErr_Occurred());
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/* Signal failure. */
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ret = NULL;
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Notice the ``except:`` block falls through to the ``finally:`` block.
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.. code-block:: c
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finally:
130+
/* All _local_ PyObjects declared at the entry point are Py_XDECREF'd here.
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* For new references this will free them. For borrowed references this
132+
* will return them to their previous refcount.
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*/
134+
Py_XDECREF(obj_a);
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/* Decrement the ref count of externally supplied the arguments here.
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* If you allow arg_1 == NULL then Py_XDECREF(arg_1). */
137+
Py_DECREF(arg_1);
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/* And return...*/
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return ret;
140+
}
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Here is the complete code with minimal comments:
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.. code-block:: c
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147+
static PyObject *function(PyObject *arg_1) {
148+
PyObject *obj_a = NULL;
149+
PyObject *ret = NULL;
150+
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goto try;
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try:
153+
assert(! PyErr_Occurred());
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assert(arg_1);
155+
Py_INCREF(arg_1);
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157+
/* obj_a = ...; */
158+
if (! obj_a) {
159+
PyErr_SetString(PyExc_ValueError, "Ooops.");
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goto except;
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}
162+
/* Only do this if obj_a is a borrowed reference. */
163+
Py_INCREF(obj_a);
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/* More of your code to do stuff with obj_a. */
166+
167+
/* Return object creation, ret must be a new reference. */
168+
/* ret = ...; */
169+
if (! ret) {
170+
PyErr_SetString(PyExc_ValueError, "Ooops again.");
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goto except;
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}
173+
assert(! PyErr_Occurred());
174+
assert(ret);
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goto finally;
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except:
177+
Py_XDECREF(ret);
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assert(PyErr_Occurred());
179+
ret = NULL;
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finally:
181+
/* Only do this if obj_a is a borrowed reference. */
182+
Py_XDECREF(obj_a);
183+
Py_DECREF(arg_1);
184+
return ret;
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}

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