Metaclasses for logging

[StrangeTcy]

Metaclasses for logging

[borzunov]

Hi @StrangeTcy,

Metaclasses are used for defining constants with ASCII color codes. I wanted to implement the coloring interface that resembles colorama and other popular libraries:

print(f"The following text will be red: {TextStyle.RED}red text{TextStyle.RESET}")

The usual convention among Linux tools (e.g. grep) is to enable coloring when stdout is terminal and disable it when stdout is a file, so initially I wrote code like this:

if sys.stdout.isatty():
    class TextStyle:
        RESET = "\033[0m"
        BOLD = "\033[1m"
        RED = "\033[31m"
        BLUE = "\033[34m"
        PURPLE = "\033[35m"
        ORANGE = "\033[38;5;208m"
else:
    class TextStyle:
        RESET = BOLD = RED = BLUE = PURPLE = ORANGE = ""

# It's not the exact code that was there, but this snippet shows the main idea

After a while, it turned out that it's not enough because sometimes you want to toggle coloring in your script on the fly. For example, before we added the in_ipython() function to hivemind, there was no convenient way to explicitly enable coloring in Jupyter/Colab in downstream apps like Petals. Also, some apps may want to toggle colors if a user provides --color or --no-color args (e.g. grep supports this), even though hivemind is already imported.

So, I decided to write code that (a) keeps the previous interface with constants and (b) changes the values of the "constants" depending on a certain bool variable. The solution with metaclasses was the easiest thing that came to my mind, and I'm not sure if there are less hacky ways of doing it (let me know if they exist).