Like \method{substitute()}, except that if placeholders are missing from
\var{mapping} and \var{kws}, instead of raising a \exception{KeyError}
exception, the original placeholder will appear in the resulting string
-intact. Note that other exceptions may still be raised, including
-\exception{ValueError} as described above.
+intact. Also, unlike with \method{substitute()}, any other appearances of the
+\samp{\$} will simply return \samp{\$} instead of raising
+\exception{ValueError}.
+
+While other exceptions may still occur, this method is called ``safe'' because
+substitutions always tries to return a usable string instead of raising an
+exception. In another sense, \method{safe_substitute()} may be anything other
+than safe, since it will silently ignore malformed templates containing
+dangling delimiters, unmatched braces, or placeholders that are not valid
+Python identifiers.
\end{methoddesc}
\class{Template} instances also provide one public data attribute:
raises(TypeError, s.safe_substitute, d, {})
def test_delimiter_override(self):
+ eq = self.assertEqual
+ raises = self.assertRaises
class AmpersandTemplate(Template):
delimiter = '&'
s = AmpersandTemplate('this &gift is for &{who} &&')
- self.assertEqual(s.substitute(gift='bud', who='you'),
- 'this bud is for you &')
- self.assertRaises(KeyError, s.substitute)
- self.assertEqual(s.safe_substitute(gift='bud', who='you'),
- 'this bud is for you &')
- self.assertEqual(s.safe_substitute(),
- 'this &gift is for &{who} &')
+ eq(s.substitute(gift='bud', who='you'), 'this bud is for you &')
+ raises(KeyError, s.substitute)
+ eq(s.safe_substitute(gift='bud', who='you'), 'this bud is for you &')
+ eq(s.safe_substitute(), 'this &gift is for &{who} &')
s = AmpersandTemplate('this &gift is for &{who} &')
- self.assertRaises(ValueError, s.substitute,
- dict(gift='bud', who='you'))
- self.assertRaises(ValueError, s.safe_substitute)
+ raises(ValueError, s.substitute, dict(gift='bud', who='you'))
+ eq(s.safe_substitute(), 'this &gift is for &{who} &')
+
def test_main():
from test import test_support