SIPPackage¶
SIP is a tool that makes it very easy to create Python bindings for C and C++ libraries. It was originally developed to create PyQt, the Python bindings for the Qt toolkit, but can be used to create bindings for any C or C++ library.
SIP comprises a code generator and a Python module. The code generator processes a set of specification files and generates C or C++ code which is then compiled to create the bindings extension module. The SIP Python module provides support functions to the automatically generated code.
Phases¶
The SIPPackage
base class comes with the following phases:
configure
- configure the packagebuild
- build the packageinstall
- install the package
By default, these phases run:
$ python configure.py --bindir ... --destdir ...
$ make
$ make install
Important files¶
Each SIP package comes with a custom configure.py
build script,
written in Python. This script contains instructions to build the project.
Build system dependencies¶
SIPPackage
requires several dependencies. Python is needed to run
the configure.py
build script, and to run the resulting Python
libraries. Qt is needed to provide the qmake
command. SIP is also
needed to build the package. SIP is an unusual dependency in that it
must be installed in the same installation directory as the package,
so instead of a depends_on
, we use a resource
. All of these
dependencies are automatically added via the base class
extends('python')
depends_on('qt', type='build')
resource(name='sip',
url='https://www.riverbankcomputing.com/static/Downloads/sip/4.19.18/sip-4.19.18.tar.gz',
sha256='c0bd863800ed9b15dcad477c4017cdb73fa805c25908b0240564add74d697e1e',
destination='.')
Passing arguments to configure.py
¶
Each phase comes with a <phase_args>
function that can be used to pass
arguments to that particular phase. For example, if you need to pass
arguments to the configure phase, you can use:
def configure_args(self, spec, prefix):
return ['--no-python-dbus']
A list of valid options can be found by running python configure.py --help
.
Testing¶
Just because a package successfully built does not mean that it built correctly. The most reliable test of whether or not the package was correctly installed is to attempt to import all of the modules that get installed. To get a list of modules, run the following command in the site-packages directory:
$ python
>>> import setuptools
>>> setuptools.find_packages()
['QtPy5']
Large, complex packages like QtPy5
will return a long list of
packages, while other packages may return an empty list. These packages
only install a single foo.py
file. In Python packaging lingo,
a “package” is a directory containing files like:
foo/__init__.py
foo/bar.py
foo/baz.py
whereas a “module” is a single Python file. Since find_packages
only returns packages, you’ll have to determine the correct module
names yourself. You can now add these packages and modules to the
package like so:
import_modules = ['PyQt5']
When you run spack install --test=root py-pyqt5
, Spack will attempt
to import the PyQt5
module after installation.
These tests most often catch missing dependencies and non-RPATHed libraries.
External documentation¶
For more information on the SIP build system, see: