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bpo-46307: Add string.Template.get_identifiers() method (GH-30493)

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Add `string.Template.get_identifiers()` method that returns the identifiers within the template. By default, raises an error if it encounters an invalid identifier (like `substitute()`). The keyword-only argument `raise_on_invalid` can be set to `False` to ignore invalid identifiers (like `safe_substitute()`).

Automerge-Triggered-By: GH:warsaw
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Ben Kehoe 2022-01-11 12:15:42 -07:00 • committed by GitHub
parent cf496d657a
commit dce642f244
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51
Lib/test/test_string.py
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@ -475,6 +475,57 @@ class TestTemplate(unittest.TestCase):
self.assertEqual(s.substitute(dict(who='tim', what='ham')),
'tim likes to eat a bag of ham worth $100')
def test_is_valid(self):
eq = self.assertEqual
s = Template('$who likes to eat a bag of ${what} worth $$100')
self.assertTrue(s.is_valid())
s = Template('$who likes to eat a bag of ${what} worth $100')
self.assertFalse(s.is_valid())
# if the pattern has an unrecognized capture group,
# it should raise ValueError like substitute and safe_substitute do
class BadPattern(Template):
pattern = r"""
(?P<badname>.*) |
(?P<escaped>@{2}) |
@(?P<named>[_a-z][._a-z0-9]*) |
@{(?P<braced>[_a-z][._a-z0-9]*)} |
(?P<invalid>@) |
"""
s = BadPattern('@bag.foo.who likes to eat a bag of @bag.what')
self.assertRaises(ValueError, s.is_valid)
def test_get_identifiers(self):
eq = self.assertEqual
raises = self.assertRaises
s = Template('$who likes to eat a bag of ${what} worth $$100')
ids = s.get_identifiers()
eq(ids, ['who', 'what'])
# repeated identifiers only included once
s = Template('$who likes to eat a bag of ${what} worth $$100; ${who} likes to eat a bag of $what worth $$100')
ids = s.get_identifiers()
eq(ids, ['who', 'what'])
# invalid identifiers are ignored
s = Template('$who likes to eat a bag of ${what} worth $100')
ids = s.get_identifiers()
eq(ids, ['who', 'what'])
# if the pattern has an unrecognized capture group,
# it should raise ValueError like substitute and safe_substitute do
class BadPattern(Template):
pattern = r"""
(?P<badname>.*) |
(?P<escaped>@{2}) |
@(?P<named>[_a-z][._a-z0-9]*) |
@{(?P<braced>[_a-z][._a-z0-9]*)} |
(?P<invalid>@) |
"""
s = BadPattern('@bag.foo.who likes to eat a bag of @bag.what')
self.assertRaises(ValueError, s.get_identifiers)
if __name__ == '__main__':
unittest.main()