Reputation: 510
After watching ArjanCodes video on dataclasses,
I've been trying to add variables to a python dataclass from a json config file to format the font style of a print function printT in Jupyterlab.
I use ANSI escapes for the formatting which doesn't work anymore if I import the variables to the dataclass. Instead of formatting the text, the ANSI code get's printed out.
# config.json
{
"lb" : "\n",
"solid_line" : "'___'*20 + config.lb",
"dotted_line" : "'---'*20 + config.lb",
"BOLD" : "\\033[1m",
"END" : "\\033[0m"
}
# config.py
from dataclasses import dataclass
import json
@dataclass
class PrintConfig:
lb : str
solid_line : str
dotted_line : str
BOLD : str
END : str
def read_config(config_file : str) -> PrintConfig:
with open(config_file, 'r') as file:
data = json.load(file)
return(PrintConfig(**data))
# helper.py
from config import read_config
config = read_config('config.json')
def printT(title,linebreak= True,addLine = True, lineType = config.solid_line,toDisplay = None):
'''
Prints a line break, the input text and a solid line.
Inputs:
title = as string
linebreak = True(default) or False; Adds a line break before printing the title
addLine = True(default) or False; Adds a line after printing the title
lineType = solid_line(default) or dotted_line; Defines line type
toDisplay = displays input, doesnt work with df.info(),because info executes during input
'''
if linebreak:
print(config.lb)
print(config.BOLD + title + config.END)
if addLine:
print(lineType)
if toDisplay is not None:
display(toDisplay)
# test.ipynb
from helper import printT
printT('Hello World')
\033[1mHello World\033[0m
'___'*20 + config.lb
Hello World
It works if I use eval if addLine: print(eval(lineType))
but I'd like to get deeper insights into the mechanics here. Is there a way of getting it to work without eval?
Also this part "solid_line" : "'___'*20 + config.lb"
feels wrong.
Markdown as alternative to ANSI
Upvotes: 1
Views: 1095
Reputation: 50220
This string consists of an actual backslash followed by the digits 033
, etc.
"BOLD" : "\\033[1m",
To turn on bold on an ansi terminal, you need an escape character (octal 33) followed by [1m
. In Python, you can write those escape codes with a single backslash: "\033[1m"
. In a json file, you must provide the unicode codepoint of the escape character, \u001b
. If the rest is in order, you'll see boldface.
"BOLD" : "\u001b[1m",
"END" : "\u001b[0m"
As for the eval
part, you have a string containing the expression you need to evaluate. I assume you wrote it this way because you first tried without the double quotes, e.g. ,
"dotted_line" : '---'*20 + config.lb,
and you got a json syntax error. That's not surprising: Json files are data, not code, and they cannot incorporate expressions or variable references. Either place your config in a python file that you include instead of loading json, or move the dependencies to the code. Or both.
In a python file, config.py
:
config = {
"lb": "\n",
"solid_line" : '___'*20,
...
In helper.py
:
...
if addLine:
print(lineType + config.lb)
Upvotes: 2
Reputation: 12214
Here's a basic configuration system. I won't add the output since it would need a screenshot but it works on bash/macos. Inspired by and [tip_colors_and_formatting]
And from (https://misc.flogisoft.com/bash/tip_colors_and_formatting):
In Bash, the character can be obtained with the following syntaxes:
\e \033 \x1B
\e
didn't work, so I went on to use to \x1B
since that worked in the linked SE answer. \033
works too, I checked.
from dataclasses import dataclass
PREFIX = "\x1B["
#these aren't configurable, they are ANSI constants so probably
#not useful to put them in a config json
CODES = dict(
prefix = PREFIX,
bold = f"1",
reset = f"{PREFIX}0m",
red = "31",
green = "32",
)
@dataclass
class PrintConfig:
bold : bool = False
color : str = ""
def __post_init__(self):
# these are calculated variables, none of client code's
# business:
self.start = self.end = ""
start = ""
if self.bold:
start += CODES["bold"] + ";"
if self.color:
start += CODES[self.color.lower()] + ";"
if start:
self.end = CODES["reset"]
#add the escape prefix, then the codes and close with m
self.start = f"{CODES['prefix']}{start}".rstrip(";") + "m"
def print(self,v):
print(f"{self.start}{v}{self.end}")
normal = PrintConfig()
normal.print("Hello World")
bold = PrintConfig(bold=1)
print(f"{bold=}:")
bold.print(" Hello World")
boldred = PrintConfig(bold=1,color="red")
print(f"{boldred=}:")
boldred.print(" Hello bold red")
#this is how you would do it from json
green = PrintConfig(**dict(color="green"))
green.print(" Little Greenie")
#inspired from https://stackoverflow.com/a/287934
print("\n\ninspired by...")
CSI = "\x1B["
print(CSI+"31;40m" + "Colored Text" + CSI + "0m")
print(CSI+"1m" + "Colored Text" + CSI + "0m")
Upvotes: 1