Jupyter Snippet CB2nd 05_config

1.5. Mastering IPython’s configuration system

%%writefile random_magics.py

from traitlets import Int, Float, Unicode, Bool
from IPython.core.magic import (Magics, magics_class,
                                line_magic)
import numpy as np

Writing random_magics.py

%%writefile random_magics.py -a

@magics_class
class RandomMagics(Magics):
    text = Unicode(u'{n}', config=True)
    max = Int(1000, config=True)
    seed = Int(0, config=True)

Appending to random_magics.py

%%writefile random_magics.py -a

    def __init__(self, shell):
        super(RandomMagics, self).__init__(shell)
        self._rng = np.random.RandomState(
            self.seed or None)

Appending to random_magics.py

%%writefile random_magics.py -a

    @line_magic
    def random(self, line):
        return self.text.format(
            n=self._rng.randint(self.max))

Appending to random_magics.py

%%writefile random_magics.py -a

def load_ipython_extension(ipython):
    ipython.register_magics(RandomMagics)

Appending to random_magics.py

%load_ext random_magics

%random

'430'

%random

'305'

ipython --RandomMagics.text='Your number is {n}.' \
        --RandomMagics.max=10 \
        --RandomMagics.seed=1

c.RandomMagics.text = 'random {n}'

from traitlets.config import Configurable
from traitlets import Float

class MyConfigurable(Configurable):
    myvariable = Float(100.0, config=True)

c = get_config()
c.MyConfigurable.myvariable = 123.