New submission from rech <r.rechkem...@web.de>:
A common pattern is to check numeric input like this:
a = input()
try:
int(a) # or float(a)
except ValueError:
print("Bad input")
One would expect this to work with decimal.Decimal(a), too. But, as
Decimal.__init__ raises decimal.InvalidOperation instead of a
ValueError, it fails.
Making Decimal.__init__ raise a ValueError in this context would be an
incompatible change. Also, making decimal.InvalidOperation a subclass of
ValueError might not be correct.
It would be best to create a new an more specific exception for this
case, a subclass of both decimal.InvalidOperation and ValueError. This
would keep all functionality and enable this kind of intuitive use.
----------
components: Library (Lib)
messages: 79814
nosy: lemburg, rech
severity: normal
status: open
title: decimal.Decimal.__init__ should raise an instance of ValueError
type: behavior
versions: Python 2.4, Python 2.5, Python 2.6, Python 2.7, Python 3.0, Python 3.1
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue4940>
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