fiicha 0.2.0

Single-line Configuration

from fiicha import parse_feature_flags_string

flags_string = "release_x !use_new_algorithm"  # stored in config
ff = MyProjectFeatureFlags(parse_feature_flags_string(flags_string))

print(ff.release_x)  # True
print(ff.use_new_algorithm)  # False

Load Flags From Environment Variables

import os
from fiicha import feature_flags_from_environ

os.environ["MYPROJ_FEATURE_RELEASE_X"] = "True"  # can also be 1, t, yes, on
os.environ["MYPROJ_FEATURE_USE_NEW_ALGORITHM"] = "False"  # can also be 0, f, no, off or empty string

ff = MyProjectFeatureFlags(feature_flags_from_environ("MYPROJ_FEATURE_"))

print(ff.release_x)  # True
print(ff.use_new_algorithm)  # False

Automatically Document Your Feature Flags

from fiicha import make_napoleon_doc, make_sphinx_doc

class GoogleStyleDocFeatureFlags(FeatureFlags, make_doc=make_napoleon_doc):
    a = FeatureFlag("Enable feature A")
    b = FeatureFlag("Enable feature B")

class SphinxStyleDocFeatureFlags(FeatureFlags, make_doc=make_sphinx_doc):
    x = FeatureFlag("Enable feature X")
    y = FeatureFlag("Enable feature Y")

print(GoogleStyleDocFeatureFlags.__doc__)
print(SphinxStyleDocFeatureFlags.__doc__)

Context Variable Support

You might want to do A/B testing or otherwise toggle feature flags for individual users without affecting the rest of the system. For such cases, there is FeatureFlagsContext - a wrapper around ContextVar. It copies current feature flags and sets them as new context variable on enter and resets them back on exit. This way you will be able to achieve global feature flags protection from changes made within context of a request or a task.

from contextvars import ContextVar
from fiicha import FeatureFlag, FeatureFlags, FeatureFlagsContext

class MyFeatureFlags(FeatureFlags):
    a = FeatureFlag("Enable feature A")
    b = FeatureFlag("Enable feature B")

root = MyFeatureFlags()
var: ContextVar[MyFeatureFlags] = ContextVar("test", default=root)
ff_ctx = FeatureFlagsContext(var)

with ff_ctx:
    ff = var.get()
    ff.a = True

    assert ff is not root  # is a copy

assert not root.a  # not changed