Problem

There was a regression in cachier v3.1.2 where enable_caching() and disable_caching() calls did not affect decorators that were defined when caching was in a different state. This broke the expected behavior where global caching enable/disable should work for all existing cached functions.

Consider this example that worked in v3.0.1 but failed in v3.1.2:

import datetime
import cachier

# Start with caching disabled
cachier.set_default_params(caching_enabled=False, separate_files=True)

class Test:
    def __init__(self, cache_ttl=None):
        self.counter = 0
        if cache_ttl is not None:
            stale_after = datetime.timedelta(seconds=cache_ttl)
            cachier.set_default_params(stale_after=stale_after)
            cachier.enable_caching()  # This should enable caching for existing decorators

    @cachier.cachier()  # Decorator defined when caching was disabled
    def test(self, param):
        self.counter += 1
        assert self.counter < 2  # Should only be called once due to caching
        return param

t = Test(cache_ttl=1)
t.test("a")
t.test("a")  # This should come from cache, not call the function again

Root Cause

The issue was in src/cachier/core.py where _global_params.caching_enabled was imported statically at decorator definition time rather than being checked dynamically at function call time. This meant that decorators captured a snapshot of the caching state when they were defined, and subsequent calls to enable_caching() or disable_caching() had no effect on them.

Solution

Made the caching_enabled check dynamic by:

1. Removing the static import of _global_params from the cachier decorator function
2. Adding a dynamic import of _global_params in the _call function right before the caching check
3. This ensures that each function call checks the current global caching state, not the state from when the decorator was defined

The fix is minimal and surgical, following the same pattern used for other dynamic parameters in the codebase.

Changes

• Fixed: Dynamic checking of _global_params.caching_enabled in function calls
• Added: Comprehensive test coverage for the regression scenario
• Verified: Existing functionality remains unchanged

Testing

Added three test cases that verify:

1. Decorators defined when caching is disabled can be enabled later
2. Decorators defined when caching is enabled can be disabled later
3. The exact scenario from the original issue report works correctly

Fixes #254.

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