Updating path on a File/MultiFileSelector Parameter updates objects

param/__init__.py

@@ -2486,6 +2486,10 @@ class FileSelector(Selector):
     """
     __slots__ = ['path']
 
+    _slot_defaults = _dict_update(
+        Selector._slot_defaults, path="",
+    )
+
     @typing.overload
     def __init__(
         self,
@@ -2497,32 +2501,32 @@ def __init__(
         ...
 
     @_deprecate_positional_args
-    def __init__(self, default=Undefined, *, path="", **kwargs):
+    def __init__(self, default=Undefined, *, path=Undefined, **kwargs):
         self.default = default
         self.path = path
-        if default is Undefined:
-            self.update()
-        else:
-            self.update(default=False)
+        self.update(path=path)
+        if default is not Undefined:
+            self.default = default
         super().__init__(default=self.default, objects=self.objects, **kwargs)
 
     def _on_set(self, attribute, old, new):
         super()._on_set(attribute, new, old)
         if attribute == 'path':
-            self.update()
+            self.update(path=new)
 
-    def update(self, default=True):
-        if self.path == "":
+    def update(self, path=Undefined):
+        if path is Undefined:
+            path = self.path
+        if path == "":
             self.objects = []
         else:
             # Convert using os.fspath and pathlib.Path to handle ensure
             # the path separators are consistent (on Windows in particular)
-            pathpattern = os.fspath(pathlib.Path(self.path))
+            pathpattern = os.fspath(pathlib.Path(path))
             self.objects = sorted(glob.glob(pathpattern))
         if self.default in self.objects:
             return
-        if default:
-            self.default = self.objects[0] if self.objects else None
+        self.default = self.objects[0] if self.objects else None
 
     def get_range(self):
         return _abbreviate_paths(self.path,super().get_range())
@@ -2573,6 +2577,10 @@ class MultiFileSelector(ListSelector):
     """
     __slots__ = ['path']
 
+    _slot_defaults = _dict_update(
+        Selector._slot_defaults, path="",
+    )
+
     @typing.overload
     def __init__(
         self,
@@ -2584,21 +2592,25 @@ def __init__(
         ...
 
     @_deprecate_positional_args
-    def __init__(self, default=Undefined, *, path="", **kwargs):
+    def __init__(self, default=Undefined, *, path=Undefined, **kwargs):
         self.default = default
         self.path = path
-        self.update()
+        self.update(path=path)
         super().__init__(default=default, objects=self.objects, **kwargs)
 
     def _on_set(self, attribute, old, new):
         super()._on_set(attribute, new, old)
         if attribute == 'path':
-            self.update()
+            self.update(path=new)
 
-    def update(self):
-        self.objects = sorted(glob.glob(self.path))
+    def update(self, path=Undefined):
+        if path is Undefined:
+            path = self.path
+        self.objects = sorted(glob.glob(path))
         if self.default and all([o in self.objects for o in self.default]):
             return
+        elif not self.default:
+            return
         self.default = self.objects
 
     def get_range(self):

tests/testfileselector.py

@@ -116,6 +116,14 @@ def test_set_path_and_update(self):
         # Default updated but not the value itself
         assert p.b == self.fa
 
+    def test_path_autoupdate(self):
+        p = self.P()
+        p.param.b.path = self.glob2
+        assert p.param.b.objects == [self.fc, self.fd]
+        assert p.param.b.default in [self.fc, self.fd]
+        # Default updated but not the value itself
+        assert p.b == self.fa
+
     def test_get_range(self):
         p = self.P()
         r = p.param.a.get_range()

tests/testmultifileselector.py

@@ -121,6 +121,14 @@ def test_set_path_and_update(self):
         # Default updated but not the value itself
         assert p.b == [self.fa]
 
+    def test_path_autoupdate(self):
+        p = self.P()
+        p.param.b.path = self.glob2
+        assert sorted(p.param.b.objects) == sorted([self.fc, self.fd])
+        assert sorted(p.param.b.default) == sorted([self.fc, self.fd])
+        # Default updated but not the value itself
+        assert p.b == [self.fa]
+
     def test_get_range(self):
         p = self.P()
         r = p.param.a.get_range()