Python is dumb. Also, tiny solenoids!

Python is a great language. It's readable, it looks nice, and it does lots of really cool things.

It's also got quirks.

For example:

x = [1, 2, 3, 4]

sets the variable x to be the list 1, 2, 3, 4. If you then set

y = x

and ask for y, it will also return the list 1-4. The weird part is what happens when you change x after this, then ask for y.

x = [2, 3, 4, 5]

>>>print(y)

[2, 3, 4, 5]

The reason for this is that the variables are pointing at the same object, instead of y being pointed at an independent duplicate of x. This caused a bug where instead of creating a 'piano roll' of valves on vs. last change, one loop in the code created a great big set of zeros.

I don't understand the point of this design choice on the part of the python developers, but I found a way to deal with it.

In other news, solenoids arrived. They're very small.

Very small.

They also draw 600 mA at 12v, which is inconvenient. They get extremely hot in a short period of time, and therefore are not suitable for connection to the control board without current-limiting resistors.

In addition, they are pull-type but have no return spring, so I need to do something about that. I found a company online called Century Spring and I've asked for a sample of the springs (tapered and very small diameter, impossible to find elsewhere) and E-clips (1 mm groove diameter, unreasonably expensive in many places, less than 3¢ per at CS), which they have agreed to send. I'm hopeful in that department, although I'm a bit disappointed that there's seemingly no inexpensive, simple solution for this part of the project. I don't mind fiddly bits and occasional kludging to make something work, but having to go through three or four different companies just to get solenoids sorted seems a bit much.