TIL Python: f"hello {thing!r}"

 When formatting strings in Python, you can use a suffix to run a conversion on it:

Three conversion flags are currently supported: '!s' which calls str() on the value, '!r' which calls repr() and '!a' which calls ascii().

Some examples:

"Harold's a clever {0!s}"        # Calls str() on the argument first
"Bring out the holy {name!r}"    # Calls repr() on the argument first
"More {!a}"                      # Calls ascii() on the argument first

 I ran into it while reading tiktoken/core.py:

    def __repr__(self) -> str:

        return f"<Encoding {self.name!r}>"

Fixing Open AI Retro Gym - Windows Integration UI crash

 I had trouble getting the Windows Integration UI to work - it kept crashing.  It turns out you need to drop the downloaded exe in your python retro package's install directory. You can find that directory using:

import retro

print(retro.__file__)

 See also: https://github.com/openai/retro/issues/159

Bookmark all tabs at once in firefox

You can bookmark all the tabs in the current window at once in Firefox (in 2020) using ctrl-shift-d.

via askvg

Sharing a mouse and keyboard between computers

I wanted to share a mouse and keyboard between two computers today. It happens to be between two Windows PCs, so I tried out Microsoft's Mouse Without Borders, instead of my usual Synergy (or US224 USB Sharing Device).

 I like it. It's easy to install, and has the settings I want.

• Benefits over Synergy: It's free (Synergy you need to compile from source, or pay for). 
• Benefits over my USB Sharing Device: Sharing Device takes several seconds to switch computers, Mouse Without Borders does not. 
• Downside to Mouse Without Borders: Windows only.

Another shadertoy experiment.

Another shadertoy experiment.  There is a long and slightly boring story behind it, but I think I'll just show it to you. You can click in different places to change its settings.

wrong bash.exe when installing Windows Subsystem for Linux

If you're following the instructions at https://msdn.microsoft.com/en-au/commandline/wsl/install_guide to get Microsoft's Linux environment installed, but you also have a Ruby devkit on your path, the "Run bash" instruction doesn't work.  Because it runs the devkit bash instead of the WSL bash.

You want "Run c:\windows\system32\bash" instead.

TIL - harvesting energy by radiating heat into space

Today I learned:

• You (well, researchers) can passively cool an object by about 37°C by carefully radiating heat into space. Nature - Radiative cooling to deep sub-freezing temperatures through a 24-h day–night cycle
• They're working on using such systems to generate power: PNAS - Harvesting renewable energy from Earth’s mid-infrared emissions

I like that.