Add named constructors for Thing.

PiperOrigin-RevId: 577250818

nisaba/scripts/natural_translit/utils/type_op.py

@@ -92,14 +92,53 @@ class Thing:
     values point to the same phoneme in the inventory.
   """
 
-  def __init__(
-      self,
-      alias: str = '', text: str = '',
-      value: ... = UNSPECIFIED, allow_none: bool = False
-  ):
-    self.alias = alias
-    self.text = text
-    self.value = value_of(value) if exists(value, allow_none) else self
+  def __init__(self):
+    c = class_of(self)
+    self.alias = '%s_%d' % (c, hash(self))
+    self.text = 'Undefined %s' % c
+    self.value = self
+
+  @classmethod
+  def named(cls, alias: str) -> 'Thing':
+    new = cls()
+    new.set_alias(alias)
+    new.text = class_and_alias(new)
+    return new
+
+  @classmethod
+  def from_value(cls, value: ...) -> 'Thing':
+    """Makes a Thing from a value.
+
+    Args:
+      value: If the value is an object with 'value' attribute, the value is
+        set to value.value in order to avoid nesting values in dynamically
+        created things and making their equivalence invisible to is_equal().
+        If this is undesirable, use store_as().
+
+    Returns:
+      Thing
+    """
+    new = cls()
+    value = value_of(value)
+    new.text = 'from:%s' % class_and_text(value)
+    new.value = value_of(value)
+    return new
+
+  @classmethod
+  def store_as(cls, alias: str, value: ...) -> 'Thing':
+    """Makes a Thing with a custom alias and value."""
+    new = cls()
+    new.set_alias(alias)
+    new.text = 'store_%s:%s' % (new.alias, class_and_text(value))
+    new.value = value
+    return new
+
+  def set_alias(self, alias: str) -> None:
+    # TODO: ensure alias conforms to inventory field name restrictions.
+    if alias:
+      self.alias = alias
+    else:
+      debug_message('set_alias', 'empty alias is not allowed')
 
 # Union types
 
@@ -141,8 +180,11 @@ def class_of(a: ...) -> str:
 def text_of(a: ...) -> str:
   """Returns str() for objects with no text attribute."""
   if hasattr(a, 'text'):
-    return ('Textless %s' % class_of(a)) if is_empty(a.text) else a.text
-  return a.string() if isinstance(a, pyn.Fst) else str(a)
+    text = a.text
+  elif isinstance(a, pyn.Fst):
+    text = a.string()
+  else: text = str(a)
+  return text if text else '<no_text>'
 
 
 def texts_of(*args) -> str:
@@ -154,6 +196,14 @@ def alias_of(a: ...) -> str:
   return a.alias if hasattr(a, 'alias') and not_empty(a.alias) else text_of(a)
 
 
+def class_and_alias(a: ...) -> str:
+  return '%s_%s' % (class_of(a), alias_of(a))
+
+
+def class_and_text(a: ...) -> str:
+  return '%s_%s' % (class_of(a), text_of(a))
+
+
 def value_of(a: ...) -> ...:
   """If a has no value attribute, returns a."""
   return a.value if isinstance(a, Thing) else a
@@ -270,7 +320,7 @@ def enforce_thing(t: ...) -> Thing:
   debug_message(
       'enforce_thing', 'Thing from %s: %s' % (class_of(t), text_of(t))
   )
-  return Thing(text=text_of(t), value=t)
+  return Thing.from_value(t)
 
 # Attribute functions with type check.
 
@@ -586,12 +636,12 @@ def enforce_set(
       try:
         result.add(element)
       except TypeError:
-        result.add(Thing(value=element))
+        result.add(Thing.from_value(element))
   else:
     try:
       result.add(s)
     except TypeError:
-      result.add(Thing(value=s))
+      result.add(Thing.from_value(s))
   return result
 
 

nisaba/scripts/natural_translit/utils/type_op_test.py

@@ -23,11 +23,12 @@
 
 D = collections.namedtuple('D', ['k'])
 _D1 = D('v')
-_T0 = t.Thing(alias='T0', text='t0', value=0)
-_T1 = t.Thing(alias='T1', text='t1', value=t.UNSPECIFIED)
-_T2 = t.Thing(alias='T2', text='', value=_T0)
-_T3 = t.Thing(alias='', text='t3', value=_T1)
-_T4 = t.Thing(alias='T4', text='t4', value=_T1)
+_T0 = t.Thing.store_as(alias='T0', value=0)
+_T1 = t.Thing.named(alias='T1')
+_T2 = t.Thing.from_value(value=_T0)
+_T3 = t.Thing.store_as(alias='', value=_T1)
+_T4 = t.Thing.store_as(alias='T4', value=_T1)
+_T5 = t.Thing.store_as(alias='T5', value=t.pyn.accep(''))
 
 
 class TypeOpTest(absltest.TestCase):
@@ -140,10 +141,10 @@ def test_get_attribute_type(self):
     )
 
   def test_text_of_thing(self):
-    self.assertEqual(t.text_of(_T1), 't1')
+    self.assertEqual(t.text_of(_T1), 'Thing_T1')
 
   def test_text_of_thing_empty(self):
-    self.assertEqual(t.text_of(_T2), 'Textless Thing')
+    self.assertEqual(t.text_of(_T5), 'store_T5:Fst_<no_text>')
 
   def test_text_of_str(self):
     self.assertEqual(t.text_of('abc'), 'abc')
@@ -167,7 +168,7 @@ def test_alias_of_thing(self):
     self.assertEqual(t.alias_of(_T1), 'T1')
 
   def test_alias_of_thing_empty(self):
-    self.assertEqual(t.alias_of(_T3), 't3')
+    self.assertNotEmpty(t.alias_of(_T3))
 
   def test_alias_of_list(self):
     self.assertEqual(t.alias_of([0, 1]), '[0, 1]')
@@ -387,7 +388,7 @@ def test_enforce_dict_namedtuple(self):
 
   def test_enforce_dict_thing(self):
     self.assertEqual(
-        t.enforce_dict(_T1), {'alias': 'T1', 'text': 't1', 'value': _T1}
+        t.enforce_dict(_T1), {'alias': 'T1', 'text': 'Thing_T1', 'value': _T1}
     )
 
   def test_enforce_dict_no_key(self):