fix(binary): swapping out values with a different field now updates t…

…he container size

src/configuraptor/binary_config.py

@@ -122,6 +122,17 @@ def _get_length(cls) -> int:
 
         return struct.calcsize(fmt)
 
+    def __setattr__(self, key: str, value: typing.Any) -> None:
+        """
+        When setting a new field for this config, update the _fields property to have the correct new type + size.
+        """
+        if not key.startswith("_") and isinstance(value, BinaryConfig):
+            field = self._fields[key]
+            field.klass = value.__class__
+            field.length = value.__class__._get_length()
+
+        return super().__setattr__(key, value)
+
 
 @dataclass
 class _BinaryField:

tests/test_binary.py

@@ -86,3 +86,25 @@ def test_binary_config_with_external_block():
     assert data.second.major == 0
 
     assert data._pack() == v1 + v2
+
+class IsNumber(BinaryConfig):
+    value = BinaryField(int, format="h")
+
+class IsBigNumber(BinaryConfig):
+    value = BinaryField(int, format="l")
+
+class HasNumber(BinaryConfig):
+    contains = BinaryField(IsNumber)
+
+
+def test_resize_config():
+    inst = HasNumber()
+    assert inst._get_length() == 2
+    inst.contains = 12
+    assert inst._get_length() == 2
+
+    big_num = IsBigNumber()
+    big_num.value = 420
+
+    inst.contains = big_num
+    assert inst._get_length() == 8