Message 86656 - Python tracker (original) (raw)

Mark Dickinson wrote:

What should the format specifier mini-language for complex numbers look like? Should it look like the existing mini-language for floats, but have the format specified twice, with some sort of delimiter?

This sounds clumsy to me. I'd guess that in most uses you'd want the same format for both pieces.

I agree, and mostly I was just trying to spark some discussion and show how (absurdly) far we can take this.

Or just specified once, and use that for both parts?

That doesn't sound unreasonable. But there might need to be some thinking about exactly what a '+' modifier means, or how you pad with zeros on the left when you've got two pieces to pad.

How about this:

• we have a single specifier with the same format as floats
• we force the sign on the imaginary part to be '+', no matter what was specified
• we add a 'j' after the imaginary part
• we ignore any width specified (and therefor any alignment and padding)

It seems simplest just to tell people to format the real and imaginary parts by hand. As it isn't totally obvious how to do this (e.g., remembering the '+' for the imaginary part), perhaps there should be a recipe in the docs somewhere?

When we document the above approach, we note the way to get full control as mentioned in a prior message.

I guess we should put the docs in with string formatting (since that's where the other builtin types are documented), although really it belongs in complex.format by itself. But I doubt anyone would find it there. Maybe we could to add a pointer from the string formatting to complex.format.