--- a/configmix/config.py	Fri Nov 19 15:52:01 2021 +0100
+++ b/configmix/config.py	Sat Nov 20 13:52:08 2021 +0100
@@ -50,7 +50,169 @@
                 return v
 
 
-class Configuration(_AttributeDict):
+class CoercingMethodsMixin(object):
+
+    """Mixin to provide some common implementations for retrieval
+    methods that convert return values to a fixed type (int, bool,
+    float).
+
+    Both :class:`~.Configuration` and :class:`~._JailedConfiguration` use
+    this mixin.
+
+    """
+
+    def getintvarl_s(self, *path, **kwds):
+        """Get a (possibly substituted) variable and coerce text to a
+        number.
+
+        """
+        s = self.getvarl_s(*path, **kwds)
+        if isinstance(s, Configuration._TEXTTYPE):
+            return int(s, 0)
+        else:
+            return s
+
+    def getfirstintvarl_s(self, *paths, **kwds):
+        """Get a (possibly substituted) variable and coerce text to a
+        number.
+
+        """
+        s = self.getfirstvarl_s(*paths, **kwds)
+        if isinstance(s, Configuration._TEXTTYPE):
+            return int(s, 0)
+        else:
+            return s
+
+    def getintvar_s(self, varname, default=_MARKER):
+        """Get a (possibly substituted) variable and coerce text to a
+        number.
+
+        """
+        s = self.getvar_s(varname, default=default)
+        if isinstance(s, Configuration._TEXTTYPE):
+            return int(s, 0)
+        else:
+            return s
+
+    def getfirstintvar_s(self, *varnames, **kwds):
+        """A variant of :meth:`~.getintvar_s` that returns the first found
+        variable in the list of given variables in `varnames`.
+
+        """
+        s = self.getfirstvar_s(*varnames, **kwds)
+        if isinstance(s, Configuration._TEXTTYPE):
+            return int(s, 0)
+        else:
+            return s
+
+    def getboolvarl_s(self, *path, **kwds):
+        """Get a (possibly substituted) variable and convert text to a
+        boolean
+
+        """
+        s = self.getvarl_s(*path, **kwds)
+        if isinstance(s, Configuration._TEXTTYPE):
+            sl = s.strip().lower()
+            if sl not in self._BOOL_CVT:
+                raise ValueError("Not a boolean: %r" % s)
+            return self._BOOL_CVT[sl]
+        else:
+            return s
+
+    def getfirstboolvarl_s(self, *paths, **kwds):
+        """Get a (possibly substituted) variable and convert text to a
+        boolean
+
+        """
+        s = self.getfirstvarl_s(*paths, **kwds)
+        if isinstance(s, Configuration._TEXTTYPE):
+            sl = s.strip().lower()
+            if sl not in self._BOOL_CVT:
+                raise ValueError("Not a boolean: %r" % s)
+            return self._BOOL_CVT[sl]
+        else:
+            return s
+
+    def getboolvar_s(self, varname, default=_MARKER):
+        """Get a (possibly substituted) variable and convert text to a
+        boolean
+
+        """
+        s = self.getvar_s(varname, default=default)
+        if isinstance(s, Configuration._TEXTTYPE):
+            sl = s.strip().lower()
+            if sl not in self._BOOL_CVT:
+                raise ValueError("Not a boolean: %r" % s)
+            return self._BOOL_CVT[sl]
+        else:
+            return s
+
+    def getfirstboolvar_s(self, *varnames, **kwds):
+        """A variant of :meth:`~.getboolvar_s` that returns the first found
+        variable in the list of given variables in `varnames`.
+
+        """
+        s = self.getfirstvar_s(*varnames, **kwds)
+        if isinstance(s, Configuration._TEXTTYPE):
+            sl = s.strip().lower()
+            if sl not in self._BOOL_CVT:
+                raise ValueError("Not a boolean: %r" % s)
+            return self._BOOL_CVT[sl]
+        else:
+            return s
+
+    # Conversion of booleans
+    _BOOL_CVT = {
+        u('1'): True, u('yes'): True, u('true'): True, u('on'): True,
+        u('0'): False, u('no'): False, u('false'): False, u('off'): False
+    }
+
+    def getfloatvarl_s(self, *path, **kwds):
+        """Get a (possibly substituted) variable and convert text to a
+        float
+
+        """
+        s = self.getvarl_s(*path, **kwds)
+        if isinstance(s, Configuration._TEXTTYPE):
+            return float(s)
+        else:
+            return s
+
+    def getfirstfloatvarl_s(self, *path, **kwds):
+        """Get a (possibly substituted) variable and convert text to a
+        float
+
+        """
+        s = self.getfirstvarl_s(*path, **kwds)
+        if isinstance(s, Configuration._TEXTTYPE):
+            return float(s)
+        else:
+            return s
+
+    def getfloatvar_s(self, varname, default=_MARKER):
+        """Get a (possibly substituted) variable and convert text to a
+        float
+
+        """
+        s = self.getvar_s(varname, default)
+        if isinstance(s, Configuration._TEXTTYPE):
+            return float(s)
+        else:
+            return s
+
+    def getfirstfloatvar_s(self, varname, default=_MARKER):
+        """Get a (possibly substituted) variable and convert text to a
+        float
+
+        """
+        s = self.getfirstvar_s(varname, default)
+        if isinstance(s, Configuration._TEXTTYPE):
+            return float(s)
+        else:
+            return s
+
+
+class Configuration(CoercingMethodsMixin, _AttributeDict):
 
     """The configuration dictionary with attribute support or
     variable substitution.
@@ -297,156 +459,6 @@
         else:
             return default
 
-    def getintvarl_s(self, *path, **kwds):
-        """Get a (possibly substituted) variable and coerce text to a
-        number.
-
-        """
-        s = self.getvarl_s(*path, **kwds)
-        if isinstance(s, self._TEXTTYPE):
-            return int(s, 0)
-        else:
-            return s
-
-    def getfirstintvarl_s(self, *paths, **kwds):
-        """Get a (possibly substituted) variable and coerce text to a
-        number.
-
-        """
-        s = self.getfirstvarl_s(*paths, **kwds)
-        if isinstance(s, self._TEXTTYPE):
-            return int(s, 0)
-        else:
-            return s
-
-    def getintvar_s(self, varname, default=_MARKER):
-        """Get a (possibly substituted) variable and coerce text to a
-        number.
-
-        """
-        s = self.getvar_s(varname, default=default)
-        if isinstance(s, self._TEXTTYPE):
-            return int(s, 0)
-        else:
-            return s
-
-    def getfirstintvar_s(self, *varnames, **kwds):
-        """A variant of :meth:`~.getintvar_s` that returns the first found
-        variable in the list of given variables in `varnames`.
-
-        """
-        s = self.getfirstvar_s(*varnames, **kwds)
-        if isinstance(s, self._TEXTTYPE):
-            return int(s, 0)
-        else:
-            return s
-
-    def getboolvarl_s(self, *path, **kwds):
-        """Get a (possibly substituted) variable and convert text to a
-        boolean
-
-        """
-        s = self.getvarl_s(*path, **kwds)
-        if isinstance(s, self._TEXTTYPE):
-            sl = s.strip().lower()
-            if sl not in self._BOOL_CVT:
-                raise ValueError("Not a boolean: %r" % s)
-            return self._BOOL_CVT[sl]
-        else:
-            return s
-
-    def getfirstboolvarl_s(self, *paths, **kwds):
-        """Get a (possibly substituted) variable and convert text to a
-        boolean
-
-        """
-        s = self.getfirstvarl_s(*paths, **kwds)
-        if isinstance(s, self._TEXTTYPE):
-            sl = s.strip().lower()
-            if sl not in self._BOOL_CVT:
-                raise ValueError("Not a boolean: %r" % s)
-            return self._BOOL_CVT[sl]
-        else:
-            return s
-
-    def getboolvar_s(self, varname, default=_MARKER):
-        """Get a (possibly substituted) variable and convert text to a
-        boolean
-
-        """
-        s = self.getvar_s(varname, default=default)
-        if isinstance(s, self._TEXTTYPE):
-            sl = s.strip().lower()
-            if sl not in self._BOOL_CVT:
-                raise ValueError("Not a boolean: %r" % s)
-            return self._BOOL_CVT[sl]
-        else:
-            return s
-
-    def getfirstboolvar_s(self, *varnames, **kwds):
-        """A variant of :meth:`~.getboolvar_s` that returns the first found
-        variable in the list of given variables in `varnames`.
-
-        """
-        s = self.getfirstvar_s(*varnames, **kwds)
-        if isinstance(s, self._TEXTTYPE):
-            sl = s.strip().lower()
-            if sl not in self._BOOL_CVT:
-                raise ValueError("Not a boolean: %r" % s)
-            return self._BOOL_CVT[sl]
-        else:
-            return s
-
-    # Conversion of booleans
-    _BOOL_CVT = {
-        u('1'): True, u('yes'): True, u('true'): True, u('on'): True,
-        u('0'): False, u('no'): False, u('false'): False, u('off'): False
-    }
-
-    def getfloatvarl_s(self, *path, **kwds):
-        """Get a (possibly substituted) variable and convert text to a
-        float
-
-        """
-        s = self.getvarl_s(*path, **kwds)
-        if isinstance(s, self._TEXTTYPE):
-            return float(s)
-        else:
-            return s
-
-    def getfirstfloatvarl_s(self, *path, **kwds):
-        """Get a (possibly substituted) variable and convert text to a
-        float
-
-        """
-        s = self.getfirstvarl_s(*path, **kwds)
-        if isinstance(s, self._TEXTTYPE):
-            return float(s)
-        else:
-            return s
-
-    def getfloatvar_s(self, varname, default=_MARKER):
-        """Get a (possibly substituted) variable and convert text to a
-        float
-
-        """
-        s = self.getvar_s(varname, default)
-        if isinstance(s, self._TEXTTYPE):
-            return float(s)
-        else:
-            return s
-
-    def getfirstfloatvar_s(self, varname, default=_MARKER):
-        """Get a (possibly substituted) variable and convert text to a
-        float
-
-        """
-        s = self.getfirstvar_s(varname, default)
-        if isinstance(s, self._TEXTTYPE):
-            return float(s)
-        else:
-            return s
-
     def _split_ns(self, s):
         nameparts = s.split(self._NS_SEPARATOR, 1)
         if len(nameparts) == 1:
@@ -693,7 +705,7 @@
         return jc
 
 
-class _JailedConfiguration(object):
+class _JailedConfiguration(CoercingMethodsMixin):
 
     """A jailed and restricted variant of :class:`Configuration`.