TIL

Python string interpolation is available via few of interfaces, as Chris at Hashrocket taught me. ...

I needed to replace an “A19” light bulb. What does “A19” mean? ...

In Vim Normal mode, * searches forward for the next occurrence of word. But what goes back? ...

If I’ve defined a function in the Python REPL, I can read its definition with inspect.getsource. ...

In the Python REPL, the help function provides a help message about its argument. ...

Jira does have a “Start Standup” button, but it’s hidden and not well documented. ...

I have a cron job that opens a program every day at a certain time. How can I also close it with a cron job? ...

My friend Josh recently wrote about a common mistake using pbcopy, Apple’s pasteboard utility. ...

Anytime Chrome loads a webpage, you can pause script execution without a debugger. ...

Sometimes in TypeScript we’d like to say a function can either have one typed prop, or the other, never both and never neither. This can be achieved with a union type and type never: type Props = { markdown: string, copy?: never } | { markdown?: never, copy: string} }; const component = ({ markdown, copy }: Props) => markdown ? parseMarkdown(markdown) : <>copy</>; console.log(component({ markdown: "### Important" })) // <h3>Important</h3> console.log(component({ copy: "Just information" })) // <>Just information</> console.log(component({ copy: "Just information", markdown: "### That conflicts })) // ❌ Type error console.log(component({})) // ❌ Type error Our component can receive a string of markdown, which it will parse, or raw copy, which it will not parse. Always just one, never both, and never neither.