Fix str() bug for tuple values #33
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Replaced the use of old-style formatting strings in __str__ methods.
At first, that seems like a dated but harmless practice, but unfortunately
While dated and seemingly a harmless practice, OSlash actually uses it
in an incorrect way.
If a program using OSlash deals with types other than strings, then the
__str__ methods for classes like `Left`, `Right`, and `Either`, OSlash
directly writes:
return '%s' % value
where `value` is an arbitrary type.
Unfortunately, '%s' % value is only guaranteed to work if the value
is a string, since Python will not call `str()` on it.
(Well, more precisely, `'%s' % value` is guaranteed to *fail* if the
value happens to be a tuple of a certain kind, since Python will try
to unpack the tuple into the string formatting operation)
The upshot is that such programs will get TypeErrors. Instead, use
Python 3.8+ f-strings to guarantee that the value is converted to a
string.
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Replaced the use of old-style formatting strings in str methods.
At first, that seems like a dated but harmless practice, but unfortunately
While dated and seemingly a harmless practice, OSlash actually uses it in an incorrect way.
If a program using OSlash deals with types other than strings, then the str methods for classes like
Left,Right, andEither, OSlash directly writes:where
valueis an arbitrary type.Unfortunately, '%s' % value is only guaranteed to work if the value is a string, since Python will not call
str()on it.(Well, more precisely,
'%s' % valueis guaranteed to fail if the value happens to be a tuple of a certain kind, since Python will try to unpack the tuple into the string formatting operation)The upshot is that such programs will get TypeErrors. Instead, use Python 3.8+ f-strings to guarantee that the value is converted to a string.