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fixes #774 
1 parent 61b01d2 commit 3be0a0c

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Lines changed: 176 additions & 12 deletions

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‎fastcore/_modidx.py‎

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@@ -18,6 +18,13 @@
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'fastcore/basics.py'),
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'fastcore.basics.AttrDictDefault.__init__': ('basics.html#attrdictdefault.__init__', 'fastcore/basics.py'),
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'fastcore.basics.BasicRepr': ('basics.html#basicrepr', 'fastcore/basics.py'),
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'fastcore.basics.DepProp': ('basics.html#depprop', 'fastcore/basics.py'),
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'fastcore.basics.DepProp.__delete__': ('basics.html#depprop.__delete__', 'fastcore/basics.py'),
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'fastcore.basics.DepProp.__get__': ('basics.html#depprop.__get__', 'fastcore/basics.py'),
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'fastcore.basics.DepProp.__init__': ('basics.html#depprop.__init__', 'fastcore/basics.py'),
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'fastcore.basics.DepProp.__set__': ('basics.html#depprop.__set__', 'fastcore/basics.py'),
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'fastcore.basics.DepProp.__set_name__': ('basics.html#depprop.__set_name__', 'fastcore/basics.py'),
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'fastcore.basics.DepProp.norm': ('basics.html#depprop.norm', 'fastcore/basics.py'),
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'fastcore.basics.Float': ('basics.html#float', 'fastcore/basics.py'),
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'fastcore.basics.GetAttr': ('basics.html#getattr', 'fastcore/basics.py'),
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'fastcore.basics.GetAttr.__dir__': ('basics.html#getattr.__dir__', 'fastcore/basics.py'),

‎fastcore/basics.py‎

Lines changed: 37 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -10,18 +10,18 @@
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'custom_dir', 'AttrDict', 'AttrDictDefault', 'NS', 'get_annotations_ex', 'eval_type', 'type_hints',
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'annotations', 'anno_ret', 'signature_ex', 'union2tuple', 'argnames', 'with_cast', 'store_attr', 'attrdict',
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'properties', 'camel2words', 'camel2snake', 'snake2camel', 'class2attr', 'getcallable', 'getattrs',
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'hasattrs', 'setattrs', 'try_attrs', 'GetAttrBase', 'GetAttr', 'delegate_attr', 'ShowPrint', 'Int', 'Str',
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'Float', 'partition', 'partition_dict', 'flatten', 'concat', 'strcat', 'detuplify', 'replicate', 'setify',
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'merge', 'range_of', 'groupby', 'last_index', 'filter_dict', 'filter_keys', 'filter_values', 'cycle',
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'zip_cycle', 'sorted_ex', 'not_', 'argwhere', 'filter_ex', 'renumerate', 'first', 'last', 'only',
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'nested_attr', 'nested_setdefault', 'nested_callable', 'nested_idx', 'set_nested_idx', 'val2idx',
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'uniqueify', 'loop_first_last', 'loop_first', 'loop_last', 'first_match', 'last_match', 'joins', 'fastuple',
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'bind', 'mapt', 'map_ex', 'compose', 'maps', 'partialler', 'instantiate', 'using_attr', 'negate', 'spread',
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'dspread', 'copy_func', 'patch_to', 'patch', 'compile_re', 'ImportEnum', 'StrEnum', 'str_enum', 'ValEnum',
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'Stateful', 'NotStr', 'PrettyString', 'even_mults', 'num_cpus', 'add_props', 'str2bool', 'str2int',
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'str2float', 'str2list', 'str2date', 'to_bool', 'to_int', 'to_float', 'to_list', 'to_date', 'typed',
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'exec_new', 'exec_import', 'sig_with_params', 'fdelegates', 'lt', 'gt', 'le', 'ge', 'eq', 'ne', 'add', 'sub',
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'mul', 'truediv', 'is_', 'is_not', 'mod']
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'hasattrs', 'setattrs', 'try_attrs', 'DepProp', 'GetAttrBase', 'GetAttr', 'delegate_attr', 'ShowPrint',
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'Int', 'Str', 'Float', 'partition', 'partition_dict', 'flatten', 'concat', 'strcat', 'detuplify',
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'replicate', 'setify', 'merge', 'range_of', 'groupby', 'last_index', 'filter_dict', 'filter_keys',
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'filter_values', 'cycle', 'zip_cycle', 'sorted_ex', 'not_', 'argwhere', 'filter_ex', 'renumerate', 'first',
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'last', 'only', 'nested_attr', 'nested_setdefault', 'nested_callable', 'nested_idx', 'set_nested_idx',
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'val2idx', 'uniqueify', 'loop_first_last', 'loop_first', 'loop_last', 'first_match', 'last_match', 'joins',
19+
'fastuple', 'bind', 'mapt', 'map_ex', 'compose', 'maps', 'partialler', 'instantiate', 'using_attr', 'negate',
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'spread', 'dspread', 'copy_func', 'patch_to', 'patch', 'compile_re', 'ImportEnum', 'StrEnum', 'str_enum',
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'ValEnum', 'Stateful', 'NotStr', 'PrettyString', 'even_mults', 'num_cpus', 'add_props', 'str2bool',
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'str2int', 'str2float', 'str2list', 'str2date', 'to_bool', 'to_int', 'to_float', 'to_list', 'to_date',
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'typed', 'exec_new', 'exec_import', 'sig_with_params', 'fdelegates', 'lt', 'gt', 'le', 'ge', 'eq', 'ne',
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'add', 'sub', 'mul', 'truediv', 'is_', 'is_not', 'mod']
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# %% ../nbs/01_basics.ipynb #0e91ed82
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from .imports import *
@@ -520,6 +520,31 @@ def try_attrs(obj, *attrs):
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except: pass
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raise AttributeError(attrs)
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# %% ../nbs/01_basics.ipynb #df28aacb
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class DepProp:
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"Property decorator with dependency update triggering"
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def __init__(self, fchange, fnorm=None): self.fchange, self.fnorm = fchange, fnorm
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def __set_name__(self, owner, name): self.attr = f'_{name}'
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def norm(self, fn):
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self.fnorm = fn
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return self
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def __get__(self, o, objtype=None):
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if o is None: return self
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return getattr(o, self.attr, None)
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def __set__(self, o, v):
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if self.fnorm: v = self.fnorm(o, v)
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change = not hasattr(o, self.attr) or v!=self.__get__(o)
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setattr(o, self.attr, v)
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if change: self.fchange(o)
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def __delete__(self, o):
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if hasattr(o, self.attr):
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delattr(o, self.attr)
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self.fchange(o)
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# %% ../nbs/01_basics.ipynb #8c571e08
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class GetAttrBase:
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"Basic delegation of `__getattr__` and `__dir__`"

‎nbs/01_basics.ipynb‎

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@@ -3095,6 +3095,138 @@
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"test_eq(try_attrs(1, 'foobar', 'real'), 1)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "df28aacb",
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"metadata": {},
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"outputs": [],
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"source": [
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"#| export\n",
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"class DepProp:\n",
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" \"Property decorator with dependency update triggering\"\n",
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" def __init__(self, fchange, fnorm=None): self.fchange, self.fnorm = fchange, fnorm\n",
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" def __set_name__(self, owner, name): self.attr = f'_{name}'\n",
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"\n",
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" def norm(self, fn):\n",
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" self.fnorm = fn\n",
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" return self\n",
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"\n",
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" def __get__(self, o, objtype=None):\n",
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" if o is None: return self\n",
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" return getattr(o, self.attr, None)\n",
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"\n",
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" def __set__(self, o, v):\n",
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" if self.fnorm: v = self.fnorm(o, v)\n",
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" change = not hasattr(o, self.attr) or v!=self.__get__(o)\n",
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" setattr(o, self.attr, v)\n",
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" if change: self.fchange(o)\n",
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"\n",
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" def __delete__(self, o):\n",
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" if hasattr(o, self.attr):\n",
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" delattr(o, self.attr)\n",
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" self.fchange(o)"
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]
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},
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{
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"cell_type": "markdown",
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"id": "f77929c0",
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"metadata": {},
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"source": [
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"`DepProp` is a descriptor that stores a value and calls a \"change\" function whenever that value changes or is deleted. This is useful for invalidating caches or triggering side effects when a dependency is updated. An optional normalizer can preprocess values before storage."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "0ce0f8d2",
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"metadata": {},
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"outputs": [],
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"source": [
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"class Square:\n",
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" @DepProp\n",
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" def width(self): self._area_cache = None\n",
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"\n",
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" @property\n",
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" def area(self):\n",
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" if self._area_cache is None: self._area_cache = self.width**2\n",
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" return self._area_cache\n",
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"\n",
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"r = Square()\n",
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"r.width = 3\n",
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"test_eq(r.area, 9)\n",
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"r.width = 5 # cache cleared automatically\n",
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"test_eq(r.area, 25)"
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]
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},
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{
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"cell_type": "markdown",
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"id": "c86ca394",
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"metadata": {},
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"source": [
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"Use the `.norm` decorator to add a normalizer that preprocesses values before storage:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "cde333c9",
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"metadata": {},
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"outputs": [],
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"source": [
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"class T:\n",
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" @DepProp\n",
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" def name(self): self.log = f'changed to {self.name}'\n",
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"\n",
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" @name.norm\n",
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" def name(self, v): return v.strip().lower()\n",
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"\n",
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"t = T()\n",
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"t.name = ' Hello '\n",
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"test_eq(t.name, 'hello')\n",
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"test_eq(t.log, 'changed to hello')"
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]
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},
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{
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"cell_type": "markdown",
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"id": "27e77787",
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"metadata": {},
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"source": [
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"Setting the same value again does *not* trigger the change function:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "a898265d",
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"metadata": {},
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"outputs": [],
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"source": [
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"t.log = 'not called'\n",
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"t.name = 'hello' # same value -- no change\n",
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"test_eq(t.log, 'not called')"
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]
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},
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{
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"cell_type": "markdown",
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"id": "ef04f745",
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"metadata": {},
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"source": [
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"Deleting the property removes the backing attribute and calls `fchange`:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "9871488b",
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"metadata": {},
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"outputs": [],
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"source": [
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"del t.name\n",
3226+
"test_eq(t.log, 'changed to None')\n",
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"test_eq(t.name, None)"
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]
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},
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{
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"cell_type": "markdown",
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"id": "cf4b62e1",

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