core: add 'core' config section, add disabled_modules/enabled_modules configs, use them for hpi modules and hpi doctor

my/core/core_config.py

@@ -0,0 +1,67 @@
+'''
+Bindings for the 'core' HPI configuration
+'''
+import re
+from typing import Sequence, Optional
+
+from .common import PathIsh
+
+try:
+    # FIXME support legacy 'common'?
+    from my.config import core as user_config # type: ignore[attr-defined]
+except Exception as e:
+    # make it defensive, because it's pretty commonly used and would be annoying if it breaks hpi doctor etc.
+    # this way it'll at least use the defaults
+    # TODO add high warning
+    user_config = object # type: ignore[assignment, misc]
+
+
+from dataclasses import dataclass
+@dataclass
+class Config(user_config):
+    # TODO if attr is set _and_ it's none, disable cache?
+    # todo or empty string?
+    # I guess flip the switch at some point when I'm confident in cachew
+    cache_dir: Optional[PathIsh] = None # FIXME use appdirs cache dir or something
+
+    # list of regexes/globs
+    # None means 'rely on disabled_modules'
+    enabled_modules : Optional[Sequence[str]] = None
+
+    # list of regexes/globs
+    # None means 'rely on enabled_modules'
+    disabled_modules: Optional[Sequence[str]] = None
+
+
+    def is_module_active(self, module: str) -> bool:
+        # todo might be nice to return the 'reason' too? e.g. which option has matched
+        should_enable  = None
+        should_disable = None
+        def matches(specs: Sequence[str]) -> bool:
+            for spec in specs:
+                # not sure because . (packages separate) matches anything, but I guess unlikely to clash
+                if re.match(spec, module):
+                    return True
+            return False
+
+        enabled  = self.enabled_modules
+        disabled = self.disabled_modules
+        if enabled is None:
+            if disabled is None:
+                # by default, enable everything? not sure
+                return True
+            else:
+                # only disable the specified modules
+                return not matches(disabled)
+        else:
+            if disabled is None:
+                # only enabled the specifid modules
+                return matches(enabled)
+            else:
+                # ok, this means the config is inconsistent. better fallback onto the 'enable everything', then the user will notice?
+                # todo add medium warning?
+                return True
+
+
+from .cfg import make_config
+config = make_config(Config)