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DBus (New Topic)¶

Principles
- commandline interface
- system vs. session/user
- XML service definitions
pydbus
openheating

Blog post on fixing the import pydbus error

$ ./unittests/run.py
Traceback (most recent call last):
  File "/home/jfasch/work/openheating/./unittests/run.py", line 8, in <module>
    from oh_tests.dbus.easysuite import suite as oh_dbus_easysuite
  File "/home/jfasch/work/openheating/unittests/oh_tests/dbus/easysuite.py", line 1, in <module>
    from .easysuite_error import suite as error_suite
  File "/home/jfasch/work/openheating/unittests/oh_tests/dbus/easysuite_error.py", line 2, in <module>
    from openheating.dbus.error import DBusHeatingError
  File "./unittests/../openheating/dbus/error.py", line 5, in <module>
    import gi.repository
ModuleNotFoundError: No module named 'gi'

Note

use interactive interpreter for that

Research:

Where does gi come from? See below, PyGObject.
Why is there no dependency on PyGObject from pydbus?

$ pip install PyGObject
Collecting PyGObject
  Using cached PyGObject-3.40.1.tar.gz (714 kB)
  Installing build dependencies ... error
  ERROR: Command errored out with exit status 1:
   command: /home/jfasch/venv/openheating/bin/python /tmp/pip-standalone-pip-ss_9wmug/__env_pip__.zip/pip install --ignore-installed --no-user --prefix /tmp/pip-build-env-9lrqmi4l/overlay --no-warn-script-location --no-binary :none: --only-binary :none: -i https://pypi.org/simple -- setuptools wheel pycairo
       cwd: None
  Complete output (38 lines):
  Collecting setuptools
    Using cached setuptools-57.0.0-py3-none-any.whl (821 kB)
  Collecting wheel
    Using cached wheel-0.36.2-py2.py3-none-any.whl (35 kB)
  Collecting pycairo
    Using cached pycairo-1.20.1.tar.gz (344 kB)
    Installing build dependencies: started
    Installing build dependencies: finished with status 'done'
    Getting requirements to build wheel: started
    Getting requirements to build wheel: finished with status 'done'
      Preparing wheel metadata: started
      Preparing wheel metadata: finished with status 'done'
  Building wheels for collected packages: pycairo
    Building wheel for pycairo (PEP 517): started
    Building wheel for pycairo (PEP 517): finished with status 'error'
    ERROR: Command errored out with exit status 1:
     command: /home/jfasch/venv/openheating/bin/python /tmp/tmpabab356k_in_process.py build_wheel /tmp/tmpt1yod7mc
         cwd: /tmp/pip-install-o4u45fjc/pycairo_33865a19ad6b4a719885f07926efe16d
    Complete output (15 lines):
    running bdist_wheel
    running build
    running build_py
    creating build
    creating build/lib.linux-x86_64-3.9
    creating build/lib.linux-x86_64-3.9/cairo
    copying cairo/__init__.py -> build/lib.linux-x86_64-3.9/cairo
    copying cairo/__init__.pyi -> build/lib.linux-x86_64-3.9/cairo
    copying cairo/py.typed -> build/lib.linux-x86_64-3.9/cairo
    running build_ext
    Package cairo was not found in the pkg-config search path.
    Perhaps you should add the directory containing `cairo.pc'
    to the PKG_CONFIG_PATH environment variable
    Package 'cairo', required by 'virtual:world', not found
    Command '['pkg-config', '--print-errors', '--exists', 'cairo >= 1.15.10']' returned non-zero exit status 1.
    ----------------------------------------
    ERROR: Failed building wheel for pycairo
  Failed to build pycairo
  ERROR: Could not build wheels for pycairo which use PEP 517 and cannot be installed directly

Install cairo headers and stuff
```
$ sudo dnf install cairo-devel
```
Next: gobject-introspection-devel

$ pip install PyGObject
Collecting PyGObject
    Using cached PyGObject-3.40.1.tar.gz (714 kB)
    Installing build dependencies ... done
    Getting requirements to build wheel ... done
      Preparing wheel metadata ... done
  Collecting pycairo>=1.16.0
    Using cached pycairo-1.20.1-cp39-cp39-linux_x86_64.whl
  Building wheels for collected packages: PyGObject
    Building wheel for PyGObject (PEP 517) ... error
    ERROR: Command errored out with exit status 1:
     command: /home/jfasch/venv/openheating/bin/python /home/jfasch/venv/openheating/lib64/python3.9/site-packages/pip/_vendor/pep517/in_process/_in_process.py build_wheel /tmp/tmpf2wjv23h
         cwd: /tmp/pip-install-4rtfumdz/pygobject_beef4432e2454eb0b7facc57fadf42b8
    Complete output (44 lines):
    running bdist_wheel
    running build
    running build_py
    creating build
    creating build/lib.linux-x86_64-3.9
    creating build/lib.linux-x86_64-3.9/pygtkcompat
    copying pygtkcompat/pygtkcompat.py -> build/lib.linux-x86_64-3.9/pygtkcompat
    copying pygtkcompat/generictreemodel.py -> build/lib.linux-x86_64-3.9/pygtkcompat
    copying pygtkcompat/__init__.py -> build/lib.linux-x86_64-3.9/pygtkcompat
    creating build/lib.linux-x86_64-3.9/gi
    copying gi/types.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/pygtkcompat.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/module.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/importer.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/docstring.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/_signalhelper.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/_propertyhelper.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/_ossighelper.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/_option.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/_gtktemplate.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/_error.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/_constants.py -> build/lib.linux-x86_64-3.9/gi
    copying gi/__init__.py -> build/lib.linux-x86_64-3.9/gi
    creating build/lib.linux-x86_64-3.9/gi/repository
    copying gi/repository/__init__.py -> build/lib.linux-x86_64-3.9/gi/repository
    creating build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/keysyms.py -> build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/__init__.py -> build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/Pango.py -> build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/Gtk.py -> build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/Gio.py -> build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/GdkPixbuf.py -> build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/Gdk.py -> build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/GObject.py -> build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/GLib.py -> build/lib.linux-x86_64-3.9/gi/overrides
    copying gi/overrides/GIMarshallingTests.py -> build/lib.linux-x86_64-3.9/gi/overrides
    running build_ext
    Package gobject-introspection-1.0 was not found in the pkg-config search path.
    Perhaps you should add the directory containing `gobject-introspection-1.0.pc'
    to the PKG_CONFIG_PATH environment variable
    Package 'gobject-introspection-1.0', required by 'virtual:world', not found
    Command '('pkg-config', '--print-errors', '--exists', 'gobject-introspection-1.0 >= 1.56.0')' returned non-zero exit status 1.

    Try installing it with: 'sudo dnf install gobject-introspection-devel'
    ----------------------------------------
    ERROR: Failed building wheel for PyGObject
  Failed to build PyGObject
  ERROR: Could not build wheels for PyGObject which use PEP 517 and cannot be installed directly

Fix it

$ sudo dnf install gobject-introspection-devel

Next, Gosh! cairo-gobject-devel

$ pip install PyGObject
Collecting PyGObject
  Using cached PyGObject-3.40.1.tar.gz (714 kB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
    Preparing wheel metadata ... done
Collecting pycairo>=1.16.0
  Using cached pycairo-1.20.1-cp39-cp39-linux_x86_64.whl
Building wheels for collected packages: PyGObject
  Building wheel for PyGObject (PEP 517) ... error
  ERROR: Command errored out with exit status 1:
   command: /home/jfasch/venv/openheating/bin/python /home/jfasch/venv/openheating/lib64/python3.9/site-packages/pip/_vendor/pep517/in_process/_in_process.py build_wheel /tmp/tmp56g_ixbz
       cwd: /tmp/pip-install-bvay4iv4/pygobject_6777f13e15934fb2b13139399b143557
  Complete output (44 lines):
  running bdist_wheel
  running build
  running build_py
  creating build
  creating build/lib.linux-x86_64-3.9
  creating build/lib.linux-x86_64-3.9/pygtkcompat
  copying pygtkcompat/pygtkcompat.py -> build/lib.linux-x86_64-3.9/pygtkcompat
  copying pygtkcompat/generictreemodel.py -> build/lib.linux-x86_64-3.9/pygtkcompat
  copying pygtkcompat/__init__.py -> build/lib.linux-x86_64-3.9/pygtkcompat
  creating build/lib.linux-x86_64-3.9/gi
  copying gi/types.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/pygtkcompat.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/module.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/importer.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/docstring.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/_signalhelper.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/_propertyhelper.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/_ossighelper.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/_option.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/_gtktemplate.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/_error.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/_constants.py -> build/lib.linux-x86_64-3.9/gi
  copying gi/__init__.py -> build/lib.linux-x86_64-3.9/gi
  creating build/lib.linux-x86_64-3.9/gi/repository
  copying gi/repository/__init__.py -> build/lib.linux-x86_64-3.9/gi/repository
  creating build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/keysyms.py -> build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/__init__.py -> build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/Pango.py -> build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/Gtk.py -> build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/Gio.py -> build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/GdkPixbuf.py -> build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/Gdk.py -> build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/GObject.py -> build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/GLib.py -> build/lib.linux-x86_64-3.9/gi/overrides
  copying gi/overrides/GIMarshallingTests.py -> build/lib.linux-x86_64-3.9/gi/overrides
  running build_ext
  Package cairo-gobject was not found in the pkg-config search path.
  Perhaps you should add the directory containing `cairo-gobject.pc'
  to the PKG_CONFIG_PATH environment variable
  Package 'cairo-gobject', required by 'virtual:world', not found
  Command '('pkg-config', '--print-errors', '--exists', 'cairo-gobject >= 0')' returned non-zero exit status 1.

  Try installing it with: 'sudo dnf install cairo-gobject-devel'
  ----------------------------------------
  ERROR: Failed building wheel for PyGObject
Failed to build PyGObject
ERROR: Could not build wheels for PyGObject which use PEP 517 and cannot be installed directly

Fix
```
$ sudo dnf install cairo-gobject-devel
```
Finally, yay!
```
$ pip install PyGObject
```
TODO: executive summary

$ dnf install all packages

Finish Meta/SEO and Stuff¶

todo
- style
  - <li> spacing
  - nested lists: space before less than after
  - /trainings/index.rst: only overview over topics, for example “C” (-> C1,2,3), “Sysprog” -> sysprog*, “Embedded” -> sysprog-embedded, raspi-hands-on, “misc” -> kernel
- title page: https://www.w3schools.com/howto/howto_css_image_transparent.asp
- courses
  - meta += see also (bisher gehaltene, unterlagen)
  - schulungen zentraler
    - auf der titelseite in die mitte
    - courses/index knackiger
    - image mit text: https://www.w3schools.com/howto/howto_css_image_transparent.asp
  - records
    - https://www.w3schools.com/howto/howto_js_read_more.asp
    - material in subdir (gegen menu clutter)
- 404 not found -> link to co.at oder so
seo/meta
- Low prio
  - courses/booking.rst
  - courses/programming-languages/index.rst
  - courses/material/sysprog/signals-slides.rst
  - courses/material/sysprog/ipc-slides.rst
- blog/2010/07/beagleboard-how-to-repair-nand-also-known-as-40w.rst
- blog/index.rst
- blog/2020/03/custom-domain-gh-pages.rst
- blog/2020/03/sphinx-gh-pages.rst
- blog/2020/02/fedora-kernel-build.rst
- blog/2012/04/Why-ps-sucks.rst
- blog/2011/01/saving-solid-state-disk-life--gentoo.rst
- blog/2011/01/porting-to-linux-there-s-always-a-better-way.rst
- index.rst
- about/myself/index.rst
- about/myself/cv-de.rst
- about/myself/projects-de.rst
- about/myself/skills-de.rst
- about/myself/contact.rst
- about/site/index.rst
- about/site/recipes.rst
- about/site/work-in-progress/layout-test.rst
- about/site/work-in-progress/todo-misc.rst
- about/site/work-in-progress/index.rst
- about/site/work-in-progress/stacks.rst
- about/site/work-in-progress/seo.rst
- about/site/work-in-progress/blog-queue/index.rst
- about/site/work-in-progress/blog-queue/github-pages-custom-domains-ssl-bad-certificate.rst
- about/site/work-in-progress/s5/tests/test-slides.rst
- about/site/work-in-progress/s5/tests/index.rst
- about/site/work-in-progress/s5/index.rst
- courses/linux/070-sysprog-fortgeschrittenes.rst
- courses/linux/700-kettner-lfs-descr.rst
- courses/linux/050-sysprog-network.rst
- courses/linux/200-raspi-hands-on.rst
- courses/linux/index.rst
- courses/linux/080-sysprog-embedded.rst
- courses/linux/020-sysprog-basics.rst
- courses/linux/060-sysprog-multithreading.rst
- courses/linux/_hidden/kettner-lfs-2013-09-16.rst
- courses/linux/010-linux-basics.rst
- courses/linux/190-kernel-programming-basics.rst
- courses/records/2020-01-10/Proposal.rst
- courses/records/2020-01-10/index.rst
- courses/records/2013-10-01/index.rst
- courses/records/index.rst
- courses/records/2019-11-12/index.rst
- courses/records/2020-03-30/index.rst
- courses/records/2019-10-28/index.rst
- courses/index.rst
- courses/programming-misc/index.rst
- courses/programming-misc/020-make.rst
- courses/programming-misc/030-svn.rst
- courses/programming-misc/050-design-patterns.rst
- courses/programming-misc/040-unittests.rst