Offline (non-Internet-connected) systems may experience failures on installing Python packages.
The package authors may not have CI setup for an offline test case, so they don't realize it's an issue.
In general, Python packages can use setup.py, setup.cfg and pyproject.toml more effectively in a Python-standard way to overcome these issues.
Install package before setup.py
Instead of telling users to manually install a package such as Numpy that's required before fully running setup.py,
use pyproject.toml instead of setuptools setup_requires.
This is because currently, setuptools assumes the computer will be internet-connected and even if the package is already installed,
setup.py will fail on an offline system.
good example (most reliable and standard)
To ensure a package like Numpy is installed before setup.py fully runs, for example where f2py is used,
have a pyproject.toml file including:
Pip is a widely-used, complex Python package installer program with a lot of legacy baggage.
The Python Software Foundation recognizes the critical need to update Pip, putting $116K to
sponsor a senior dev
to modernize Pip.
Sometimes, pip install fails to realize a .whl binary wheel is available.
Thus pip tries to download and install a package from source code.
In the case of a large package like SciPy, OpenCV or Pillow on an embedded system like the Raspberry Pi Zero,
it could take hours or even days to compile, probably failing numerous times due to missing prerequisite binary libraries.
Manual install wheel
A workaround to Pip not automatically finding the desired
.whl binary wheel
is to download it manually and install the .whl directly.
The binary wheels are often available at PyPi from the package download page, for example
For embedded systems such as Raspberry Pi, there may be non-PyPi sites such as
Download the file, then pip install from the file like:
Downloading binary Homebrew bottles without installing Homebrew can be useful to check the location of the bottle contents.
This is useful when developing Meson native-files or CMake Find*.cmake modules.
Since 2015, Homebrew distributes bottles from Bintray.
For example, HDF5 bottle may be inspected by:
tar --list -f hdf5-1.10.5_1.catalina.bottle.tar.gz
No Homebrew install is necessary for inspection, but actually using the libraries and binaries is of course best done by
Usually it's desired to check Python type annotations for an entire project.
However, when introducing type checking to a large Python project, it can be beneficial to introduce type checking gradually, to avoid massive refactoring all at once.
You will almost certainly find old code bugs due to type checking that will require refactoring, which introduces risk.
Mitigate this risk by introducing type checking gradually.
MyPy single file options
MyPy is a strongly recommended type checker, though others exist.
We typically use a per-project mypy.ini to make appropriate MyPy default behavior.
To tell MyPy to only check certain files, use the MyPy
deprecated PGI debugger
– it will be removed after 2019.
PGI Java-based pgdbg graphical debugger was for Fortran, C and C++, including the no-cost Community Edition.
The program to be debugged needs compile options -g -O0 to provide debugging information.
Example with hello.f90:
pgfortran -g hello.f90
pgdbg a.out opened the graphical Fortran debugger.
If you don't see code in the upper left of the graphical PGI debugger for your program, be sure you compiled the executable with -g -O0 options.
Like most other programs, 32-bit Python can be run on 64-bit OS.
When needing to precisely detect if the operating system is 64-bit or 32-bit in a cross-platform way,
one needs to check if Python itself is 32-bit to avoid falsely detecting that the operating system is 32 bit when the OS is actually 64 bit.
Note: This check is just for the Python interpreter.
If you're working on detecting the operating system parameters in a cross-platform-robust way, several further checks are necessary in general.
Dozens of “free” compilers exist for C, C++ and Fortran.
However, only five compiler families available at no charge support the modern features of these popular compiled languages.
GCC has broad support of modern standards on a very wide range of computing platforms.
GCC's downside in some cases can be slower runtime performance than compilers having less broad language and platform support.
IBM XL compilers are currently for POWER CPUs only e.g. ppc64le.
IBM XL compilers do not work with a typical x86-based computer.
If you have a $3000 Raptor IBM POWER9 desktop, then IBM XL may be for you.
The IBM XL compilers are high-performance compilers that have a free community edition.
IBM XL Fortran has wide support for Fortran 2008.
Many IDEs create per-project cache directories with metadata relevant to the IDE configuration for that project.
Instead of editing the .gitignore file for each repository,
ignore directories in Git system-wide for all repos as follows, for any operating system.
To avoid connection failures requiring reboot of a Windows 10 PC upon resuming from sleep/standby,
consider disabling Windows network (WiFi) connectivity during sleep.
Only certain PCs are capable of having network connectivity during sleep.
The option to disable WiFi during sleep is only present if the laptop supports it.
Windows Wifi power setting is under the Control Panel → System → Power & Sleep.
If present, uncheck under “Wi-Fi” the “stay connected…sleep” options.
Check if laptop supports Connected Standby
From Command Prompt, type:
if the response includes
Standby (S0 Low Power Idle) Network Disconnected
then the PC is set to disconnect from WiFi on sleep.
Advantages of disabling Windows Connected Standby:
save battery by not having your computer connected to Wifi while sleeping.
not connecting to possibly rogue AP as you travel about, or being subject to tracking.
some hardware (e.g. Microsoft Surface Pro) often fails to connect to Wifi on wakeup until manually going to Device Manager and disable/enable cycling the Wifi adapter.