IQ.Lvbs/pycapnp
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Merge branch 'feature/docs' into develop

Browse Source
This commit is contained in:
Jason Paryani
2013-08-18 21:49:27 -07:00
parent bbd458985e 22b3199335
commit 57903902ae
9 changed files with 826 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
.gitignore vendored
View File

@@ -39,3 +39,4 @@ capnp/*.cpp
capnp/version.py
MANIFEST
docs/_build

7
capnp/capnp.pyx
View File

@@ -4,6 +4,7 @@
# distutils: libraries = capnpc
# cython: c_string_type = str
# cython: c_string_encoding = default
# cython: embedsignature = True
cimport cython
cimport capnp_cpp as capnp
@@ -598,12 +599,10 @@ cdef class MessageReader:
def __init__(self):
raise NotImplementedError("This is an abstract base class")
cpdef getRootNode(self):
cpdef _getRootNode(self):
return _NodeReader().init(self.thisptr.getRootNode())
cpdef getRootCodeGeneratorRequest(self):
cpdef _getRootCodeGeneratorRequest(self):
return _CodeGeneratorRequestReader()._init(self.thisptr.getRootCodeGeneratorRequest())
cpdef getRootDynamicStruct(self, StructSchema schema):
return _DynamicStructReader()._init(self.thisptr.getRootDynamicStruct(schema.thisptr), self)
cpdef getRoot(self, schema):
cdef StructSchema s
if hasattr(schema, 'Schema'):

153
docs/Makefile Normal file
View File

@@ -0,0 +1,153 @@
# Makefile for Sphinx documentation
#
# You can set these variables from the command line.
SPHINXOPTS =
SPHINXBUILD = sphinx-build
PAPER =
BUILDDIR = _build
# Internal variables.
PAPEROPT_a4 = -D latex_paper_size=a4
PAPEROPT_letter = -D latex_paper_size=letter
ALLSPHINXOPTS = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
# the i18n builder cannot share the environment and doctrees with the others
I18NSPHINXOPTS = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
.PHONY: help clean html dirhtml singlehtml pickle json htmlhelp qthelp devhelp epub latex latexpdf text man changes linkcheck doctest gettext
help:
@echo "Please use \`make <target>' where <target> is one of"
@echo " html to make standalone HTML files"
@echo " dirhtml to make HTML files named index.html in directories"
@echo " singlehtml to make a single large HTML file"
@echo " pickle to make pickle files"
@echo " json to make JSON files"
@echo " htmlhelp to make HTML files and a HTML help project"
@echo " qthelp to make HTML files and a qthelp project"
@echo " devhelp to make HTML files and a Devhelp project"
@echo " epub to make an epub"
@echo " latex to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
@echo " latexpdf to make LaTeX files and run them through pdflatex"
@echo " text to make text files"
@echo " man to make manual pages"
@echo " texinfo to make Texinfo files"
@echo " info to make Texinfo files and run them through makeinfo"
@echo " gettext to make PO message catalogs"
@echo " changes to make an overview of all changed/added/deprecated items"
@echo " linkcheck to check all external links for integrity"
@echo " doctest to run all doctests embedded in the documentation (if enabled)"
clean:
-rm -rf $(BUILDDIR)/*
html:
$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
dirhtml:
$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml."
singlehtml:
$(SPHINXBUILD) -b singlehtml $(ALLSPHINXOPTS) $(BUILDDIR)/singlehtml
@echo
@echo "Build finished. The HTML page is in $(BUILDDIR)/singlehtml."
pickle:
$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle
@echo
@echo "Build finished; now you can process the pickle files."
json:
$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json
@echo
@echo "Build finished; now you can process the JSON files."
htmlhelp:
$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
@echo
@echo "Build finished; now you can run HTML Help Workshop with the" \
".hhp project file in $(BUILDDIR)/htmlhelp."
qthelp:
$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp
@echo
@echo "Build finished; now you can run "qcollectiongenerator" with the" \
".qhcp project file in $(BUILDDIR)/qthelp, like this:"
@echo "# qcollectiongenerator $(BUILDDIR)/qthelp/capnp.qhcp"
@echo "To view the help file:"
@echo "# assistant -collectionFile $(BUILDDIR)/qthelp/capnp.qhc"
devhelp:
$(SPHINXBUILD) -b devhelp $(ALLSPHINXOPTS) $(BUILDDIR)/devhelp
@echo
@echo "Build finished."
@echo "To view the help file:"
@echo "# mkdir -p $$HOME/.local/share/devhelp/capnp"
@echo "# ln -s $(BUILDDIR)/devhelp $$HOME/.local/share/devhelp/capnp"
@echo "# devhelp"
epub:
$(SPHINXBUILD) -b epub $(ALLSPHINXOPTS) $(BUILDDIR)/epub
@echo
@echo "Build finished. The epub file is in $(BUILDDIR)/epub."
latex:
$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
@echo
@echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex."
@echo "Run \`make' in that directory to run these through (pdf)latex" \
"(use \`make latexpdf' here to do that automatically)."
latexpdf:
$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
@echo "Running LaTeX files through pdflatex..."
$(MAKE) -C $(BUILDDIR)/latex all-pdf
@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
text:
$(SPHINXBUILD) -b text $(ALLSPHINXOPTS) $(BUILDDIR)/text
@echo
@echo "Build finished. The text files are in $(BUILDDIR)/text."
man:
$(SPHINXBUILD) -b man $(ALLSPHINXOPTS) $(BUILDDIR)/man
@echo
@echo "Build finished. The manual pages are in $(BUILDDIR)/man."
texinfo:
$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
@echo
@echo "Build finished. The Texinfo files are in $(BUILDDIR)/texinfo."
@echo "Run \`make' in that directory to run these through makeinfo" \
"(use \`make info' here to do that automatically)."
info:
$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
@echo "Running Texinfo files through makeinfo..."
make -C $(BUILDDIR)/texinfo info
@echo "makeinfo finished; the Info files are in $(BUILDDIR)/texinfo."
gettext:
$(SPHINXBUILD) -b gettext $(I18NSPHINXOPTS) $(BUILDDIR)/locale
@echo
@echo "Build finished. The message catalogs are in $(BUILDDIR)/locale."
changes:
$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes
@echo
@echo "The overview file is in $(BUILDDIR)/changes."
linkcheck:
$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck
@echo
@echo "Link check complete; look for any errors in the above output " \
"or in $(BUILDDIR)/linkcheck/output.txt."
doctest:
$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
@echo "Testing of doctests in the sources finished, look at the " \
"results in $(BUILDDIR)/doctest/output.txt."

35
docs/capnp.rst Normal file
View File

@@ -0,0 +1,35 @@
.. _api:
API Reference
===================
.. automodule:: capnp
.. currentmodule:: capnp
Functions
-------------
.. autofunction:: load
.. autofunction:: writeMessageToFd
.. autofunction:: writePackedMessageToFd
Readers
-------------
.. autoclass:: StreamFdMessageReader
:members:
:undoc-members:
:inherited-members:
.. autoclass:: PackedFdMessageReader
:members:
:undoc-members:
:inherited-members:
Writers
-------------
.. autoclass:: MallocMessageBuilder
:members:
:undoc-members:
:inherited-members:

294
docs/conf.py Normal file
View File

@@ -0,0 +1,294 @@
# -*- coding: utf-8 -*-
#
# capnp documentation build configuration file, created by
# sphinx-quickstart on Sat Aug 17 18:00:25 2013.
#
# This file is execfile()d with the current directory set to its containing dir.
#
# Note that not all possible configuration values are present in this
# autogenerated file.
#
# All configuration values have a default; values that are commented out
# serve to show the default.
import sys, os, string
# If extensions (or modules to document with autodoc) are in another directory,
# add these directories to sys.path here. If the directory is relative to the
# documentation root, use os.path.abspath to make it absolute, like shown here.
#sys.path.insert(0, os.path.abspath('.'))
# -- General configuration -----------------------------------------------------
# If your documentation needs a minimal Sphinx version, state it here.
#needs_sphinx = '1.0'
# Add any Sphinx extension module names here, as strings. They can be extensions
# coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
extensions = ['sphinx.ext.autodoc', 'sphinx.ext.viewcode']
# Add any paths that contain templates here, relative to this directory.
templates_path = ['_templates']
# The suffix of source filenames.
source_suffix = '.rst'
# The encoding of source files.
#source_encoding = 'utf-8-sig'
# The master toctree document.
master_doc = 'index'
# General information about the project.
project = u'capnp'
copyright = u'2013, Author'
# The version info for the project you're documenting, acts as replacement for
# |version| and |release|, also used in various other places throughout the
# built documents.
#
# The short X.Y version.
import pkg_resources
try:
release = pkg_resources.get_distribution('capnp').version
except pkg_resources.DistributionNotFound:
print 'To build the documentation, The distribution information of sandman'
print 'Has to be available. Either install the package into your'
print 'development environment or run "setup.py develop" to setup the'
print 'metadata. A virtualenv is recommended!'
sys.exit(1)
del pkg_resources
version = '.'.join(release.split('.')[:2])
# The language for content autogenerated by Sphinx. Refer to documentation
# for a list of supported languages.
#language = None
# There are two options for replacing |today|: either, you set today to some
# non-false value, then it is used:
#today = ''
# Else, today_fmt is used as the format for a strftime call.
#today_fmt = '%B %d, %Y'
# List of patterns, relative to source directory, that match files and
# directories to ignore when looking for source files.
exclude_patterns = ['_build']
# The reST default role (used for this markup: `text`) to use for all documents.
#default_role = None
# If true, '()' will be appended to :func: etc. cross-reference text.
#add_function_parentheses = True
# If true, the current module name will be prepended to all description
# unit titles (such as .. function::).
#add_module_names = True
# If true, sectionauthor and moduleauthor directives will be shown in the
# output. They are ignored by default.
#show_authors = False
# The name of the Pygments (syntax highlighting) style to use.
pygments_style = 'sphinx'
# A list of ignored prefixes for module index sorting.
#modindex_common_prefix = []
# -- Options for HTML output ---------------------------------------------------
# The theme to use for HTML and HTML Help pages. See the documentation for
# a list of builtin themes.
html_theme = 'nature'
# Theme options are theme-specific and customize the look and feel of a theme
# further. For a list of options available for each theme, see the
# documentation.
#html_theme_options = {}
# Add any paths that contain custom themes here, relative to this directory.
#html_theme_path = []
# The name for this set of Sphinx documents. If None, it defaults to
# "<project> v<release> documentation".
#html_title = None
# A shorter title for the navigation bar. Default is the same as html_title.
#html_short_title = None
# The name of an image file (relative to this directory) to place at the top
# of the sidebar.
#html_logo = None
# The name of an image file (within the static path) to use as favicon of the
# docs. This file should be a Windows icon file (.ico) being 16x16 or 32x32
# pixels large.
#html_favicon = None
# Add any paths that contain custom static files (such as style sheets) here,
# relative to this directory. They are copied after the builtin static files,
# so a file named "default.css" will overwrite the builtin "default.css".
html_static_path = ['_static']
# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
# using the given strftime format.
#html_last_updated_fmt = '%b %d, %Y'
# If true, SmartyPants will be used to convert quotes and dashes to
# typographically correct entities.
#html_use_smartypants = True
# Custom sidebar templates, maps document names to template names.
#html_sidebars = {}
# Additional templates that should be rendered to pages, maps page names to
# template names.
#html_additional_pages = {}
# If false, no module index is generated.
#html_domain_indices = True
# If false, no index is generated.
#html_use_index = True
# If true, the index is split into individual pages for each letter.
#html_split_index = False
# If true, links to the reST sources are added to the pages.
#html_show_sourcelink = True
# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
#html_show_sphinx = True
# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
#html_show_copyright = True
# If true, an OpenSearch description file will be output, and all pages will
# contain a <link> tag referring to it. The value of this option must be the
# base URL from which the finished HTML is served.
#html_use_opensearch = ''
# This is the file name suffix for HTML files (e.g. ".xhtml").
#html_file_suffix = None
# Output file base name for HTML help builder.
htmlhelp_basename = 'capnpdoc'
# -- Options for LaTeX output --------------------------------------------------
latex_elements = {
# The paper size ('letterpaper' or 'a4paper').
#'papersize': 'letterpaper',
# The font size ('10pt', '11pt' or '12pt').
#'pointsize': '10pt',
# Additional stuff for the LaTeX preamble.
#'preamble': '',
}
# Grouping the document tree into LaTeX files. List of tuples
# (source start file, target name, title, author, documentclass [howto/manual]).
latex_documents = [
('index', 'capnp.tex', u'capnp Documentation',
u'Author', 'manual'),
]
# The name of an image file (relative to this directory) to place at the top of
# the title page.
#latex_logo = None
# For "manual" documents, if this is true, then toplevel headings are parts,
# not chapters.
#latex_use_parts = False
# If true, show page references after internal links.
#latex_show_pagerefs = False
# If true, show URL addresses after external links.
#latex_show_urls = False
# Documents to append as an appendix to all manuals.
#latex_appendices = []
# If false, no module index is generated.
#latex_domain_indices = True
# -- Options for manual page output --------------------------------------------
# One entry per manual page. List of tuples
# (source start file, name, description, authors, manual section).
man_pages = [
('index', 'capnp', u'capnp Documentation',
[u'Author'], 1)
]
# If true, show URL addresses after external links.
#man_show_urls = False
# -- Options for Texinfo output ------------------------------------------------
# Grouping the document tree into Texinfo files. List of tuples
# (source start file, target name, title, author,
# dir menu entry, description, category)
texinfo_documents = [
('index', 'capnp', u'capnp Documentation',
u'Author', 'capnp', 'One line description of project.',
'Miscellaneous'),
]
# Documents to append as an appendix to all manuals.
#texinfo_appendices = []
# If false, no module index is generated.
#texinfo_domain_indices = True
# How to display URL addresses: 'footnote', 'no', or 'inline'.
#texinfo_show_urls = 'footnote'
# -- Options for Epub output ---------------------------------------------------
# Bibliographic Dublin Core info.
epub_title = u'capnp'
epub_author = u'Author'
epub_publisher = u'Author'
epub_copyright = u'2013, Author'
# The language of the text. It defaults to the language option
# or en if the language is not set.
#epub_language = ''
# The scheme of the identifier. Typical schemes are ISBN or URL.
#epub_scheme = ''
# The unique identifier of the text. This can be a ISBN number
# or the project homepage.
#epub_identifier = ''
# A unique identification for the text.
#epub_uid = ''
# A tuple containing the cover image and cover page html template filenames.
#epub_cover = ()
# HTML files that should be inserted before the pages created by sphinx.
# The format is a list of tuples containing the path and title.
#epub_pre_files = []
# HTML files shat should be inserted after the pages created by sphinx.
# The format is a list of tuples containing the path and title.
#epub_post_files = []
# A list of files that should not be packed into the epub file.
#epub_exclude_files = []
# The depth of the table of contents in toc.ncx.
#epub_tocdepth = 3
# Allow duplicate toc entries.
#epub_tocdup = True

28
docs/index.rst Normal file
View File

@@ -0,0 +1,28 @@
.. capnp documentation master file
Welcome to capnp's documentation!
=================================
This is a python wrapping of the C++ implementation of the `Capnproto <http://kentonv.github.io/capnproto/>`_ library. Here is a description, quoted from its docs:
Cap’n Proto is an insanely fast data interchange format and capability-based RPC system. Think JSON, except binary. Or think Protocol Buffers, except faster. In fact, in benchmarks, Cap’n Proto is INFINITY TIMES faster than Protocol Buffers.
The INFINITY TIMES faster part isn't so true for python, but in some simplistic benchmarks (available in the `benchmark directory of the repo <https://github.com/jparyani/capnpc-python-cpp/tree/master/benchmark>`_), capnp is 4x faster than the pure python Protocol Buffer library, and 2x faster than the C++ implementation.
Contents:
.. toctree::
:maxdepth: 4
install
quickstart
capnp
Indices and tables
==================
* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`

43
docs/install.rst Normal file
View File

@@ -0,0 +1,43 @@
.. _install:
Installation
===================
C++ Capnproto Library
---------------------
You need to install the C++ Capnproto library first. It requires a C++ compiler with C++11 support, such as GCC 4.7+ or Clang 3.2+. Follow installation docs at `http://kentonv.github.io/capnproto/install.html <http://kentonv.github.io/capnproto/install.html>`_ with an added `sudo ldconfig` after you're done installing, or if you're feeling lazy, you can run the commands below::
wget https://github.com/kentonv/capnproto/archive/master.zip
unzip master.zip
cd capnproto-master/c++
./setup-autotools.sh
autoreconf -i
./configure
make -j6 check
sudo make install
sudo ldconfig
Pip
---------------------
Using pip is by far the easiest way to install the library. After you've installed the C++ library, all you need to run is::
pip install capnp
From Source
---------------------
If you want the latest development version, you can clone the github repo and install like so::
git clone https://github.com/jparyani/capnpc-python-cpp.git
pip install capnpc-python-cpp
or::
cd capnpc-python-cpp
python setup.py install
If you don't use pip, you will need to manually install Cython, and a setuptools with a version > .7.
Once you're done installing, take a look at the :ref:`quickstart`

268
docs/quickstart.rst Normal file
View File

@@ -0,0 +1,268 @@
.. _quickstart:
Quickstart
===================
This assumes you already have the capnp library installed. If you don't, please follow the instructions at :ref:`Installation <install>` first.
In general, this library is a very light wrapping of the `Capnproto C++ library <http://kentonv.github.io/capnproto/cxx.html>`_. You can refer to its docs for more advanced concepts, or just to get a basic idea of how the python library is structured.
Load a Capnproto Schema
-------------
First you need to import the library::
import capnp
Then you can load the Capnproto schema with::
capnp.load('addressbook.capnp')
For future reference, here is the capnproto schema. Also available in the github repository under examples/addressbook.capnp::
# addressbook.capnp
0x934efea7f017fff0;
struct Person {
id @0 :UInt32;
name @1 :Text;
email @2 :Text;
phones @3 :List(PhoneNumber);
struct PhoneNumber {
number @0 :Text;
type @1 :Type;
enum Type {
mobile @0;
home @1;
work @2;
}
}
employment @4 union {
unemployed @5 :Void;
employer @6 :Text;
school @7 :Text;
selfEmployed @8 :Void;
# We assume that a person is only one of these.
}
}
struct AddressBook {
people @0 :List(Person);
}
Build a message
-------------
Message Builder
~~~~~~~~~~~~~~~~~~~
First you need to allocate a MessageBuilder for your message to go in. There is only 1 message allocator available at the moment (Malloc), although there may be more varied kinds in the future::
message = capnp.MallocMessageBuilder()
Initialize a New Capnproto Object
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Now that you have a message buffer, you need to allocate an actual object that is from your schema. In this case, we will allocate an `AddressBook`::
addressBook = message.initRoot(addressbook.AddressBook)
Notice that we used `addressbook` from the previous section: `Load a Capnproto Schema`_.
List
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allocating a list inside of an object requires use of the `init` function::
people = addressBook.init('people', 2)
For now, let's grab the first element out of this list and assign it to a variable named `alice`::
alice = people[0]
Primitive Types
~~~~~~~~~~~~~~~~~~~~~~~~~~~
For all primitive types, from the Capnproto docs:
- Boolean: Bool
- Integers: Int8, Int16, Int32, Int64
- Unsigned integers: UInt8, UInt16, UInt32, UInt64
- Floating-point: Float32, Float64
- Blobs: Text, Data
You can just assign straight to the variable with the corresponding Python type. For Blobs, you just use strings. Assignment happens just by using the `.` syntax on the object you contstructed above::
alice.id = 123
alice.name = 'Alice'
alice.email = 'alice@example.com'
Enums
~~~~~~~~~~~~~~
First we'll allocate a length one list of phonenumbers for `alice`::
alicePhone = alice.init('phones', 1)[0]
Note that even though it was a length 1 list, it was still a list that was returned, and we extracted the first (and only) element with `[0]`.
Now, enums are treated like strings, and you just assign to them like there were a Text field::
alicePhone.type = 'mobile'
If you assign an invalid value to one, you will get a ValueError::
alicePhone.type = 'foo'
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
...
ValueError: src/capnp/schema.c++:326: requirement not met: enum has no such enumerant; name = foo
Unions
~~~~~~~~~~~~~~~~~~
For the most part, you just treat them like structs::
alice.employment.school = "MIT"
Now the `school` field is the active part of the union, and we've assigned `'MIT'` to it. You can query which field is set in a union with `which()`, shown in `Reading Unions`_
Also, one weird case is for Void types in Unions (and in general, but Void is really only used in Unions). For these, you will have to assign `None` to them::
bob.employment.unemployed = None
Writing to a File
~~~~~~~~~~~~~~~~~~~
For now, the only way to serialize a message is to write it directly to a file descriptor (expect serializing to strings at some point soon)::
f = open('example.bin', 'w')
capnp.writePackedMessageToFd(f.fileno(), message)
Note the call to fileno(), since it expects a raw file descriptor. There is also `writeMessageToFd` instead of `writePackedMessageToFd`. Make sure your reader uses the same packing type.
Read a message
-------------
Reading from a file
~~~~~~~~~~~~~~~~~~~~~~
Much like before, you will have to de-serialize the message from a file descriptor::
f = open('example.bin')
message = capnp.PackedFdMessageReader(f.fileno())
Initialize a New Capnproto Object
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Just like when building, you have to actually specify which message you want to read out of buffer::
addressBook = message.getRoot(addressbook.AddressBook)
Note that this very much needs to match the type you wrote out. In general, you will always be sending the same message types out over a given channel, wrap all your types in an unnamed enum, or you need some out of band method for communicating what type a message is. Unnamed unions are defined in the .capnp file like so::
struct Message {
union {
person @0 :Person;
addressbook @1 :AddressBook;
}
}
Reading Fields
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fields are very easy to read. You just use the `.` syntax as before. Lists behave just like normal Python lists::
for person in addressBook.people:
print(person.name, ':', person.email)
for phone in person.phones:
print(phone.type, ':', phone.number)
Reading Unions
~~~~~~~~~~~~~~~~~~~~~~~~~~~
The only tricky one is unions, where you need to call `.which()` to determine the union type. The `.which()` call returns an enum, ie. a string, corresponding to the field name::
which = person.employment.which()
print(which)
if which == 'unemployed':
print('unemployed')
elif which == 'employer':
print('employer:', person.employment.employer)
elif which == 'school':
print('student at:', person.employment.school)
elif which == 'selfEmployed':
print('self employed')
print()
Full Example
------------------
Here is a full example reproduced from `examples/example.py <https://github.com/jparyani/capnpc-python-cpp/blob/master/examples/example.py>`_::
from __future__ import print_function
import os
import capnp
this_dir = os.path.dirname(__file__)
addressbook = capnp.load(os.path.join(this_dir, 'addressbook.capnp'))
def writeAddressBook(fd):
message = capnp.MallocMessageBuilder()
addressBook = message.initRoot(addressbook.AddressBook)
people = addressBook.init('people', 2)
alice = people[0]
alice.id = 123
alice.name = 'Alice'
alice.email = 'alice@example.com'
alicePhones = alice.init('phones', 1)
alicePhones[0].number = "555-1212"
alicePhones[0].type = 'mobile'
alice.employment.school = "MIT"
bob = people[1]
bob.id = 456
bob.name = 'Bob'
bob.email = 'bob@example.com'
bobPhones = bob.init('phones', 2)
bobPhones[0].number = "555-4567"
bobPhones[0].type = 'home'
bobPhones[1].number = "555-7654"
bobPhones[1].type = 'work'
bob.employment.unemployed = None
capnp.writePackedMessageToFd(fd, message)
def printAddressBook(fd):
message = capnp.PackedFdMessageReader(f.fileno())
addressBook = message.getRoot(addressbook.AddressBook)
for person in addressBook.people:
print(person.name, ':', person.email)
for phone in person.phones:
print(phone.type, ':', phone.number)
which = person.employment.which()
print(which)
if which == 'unemployed':
print('unemployed')
elif which == 'employer':
print('employer:', person.employment.employer)
elif which == 'school':
print('student at:', person.employment.school)
elif which == 'selfEmployed':
print('self employed')
print()
if __name__ == '__main__':
f = open('example', 'w')
writeAddressBook(f.fileno())
f = open('example', 'r')
printAddressBook(f.fileno())

2
examples/example.py
View File

@@ -28,7 +28,7 @@ def writeAddressBook(fd):
bobPhones[0].type = 'home'
bobPhones[1].number = "555-7654"
bobPhones[1].type = 'work'
bob.employment.unemployed = None # This is definitely bad, syntax will change at some point
bob.employment.unemployed = None
capnp.writePackedMessageToFd(fd, message)