diff options
Diffstat (limited to 'Lib/decimal.py')
| -rw-r--r-- | Lib/decimal.py | 65 |
1 files changed, 30 insertions, 35 deletions
diff --git a/Lib/decimal.py b/Lib/decimal.py index 4e5cbbb..9f77b24 100644 --- a/Lib/decimal.py +++ b/Lib/decimal.py @@ -78,30 +78,30 @@ Traceback (most recent call last): ... DivisionByZero: x / 0 >>> c = Context() ->>> c.trap_enablers[DivisionUndefined] = 0 ->>> print c.flags[DivisionUndefined] +>>> c.trap_enablers[InvalidOperation] = 0 +>>> print c.flags[InvalidOperation] 0 >>> c.divide(Decimal(0), Decimal(0)) Decimal("NaN") ->>> c.trap_enablers[DivisionUndefined] = 1 ->>> print c.flags[DivisionUndefined] +>>> c.trap_enablers[InvalidOperation] = 1 +>>> print c.flags[InvalidOperation] 1 ->>> c.flags[DivisionUndefined] = 0 ->>> print c.flags[DivisionUndefined] +>>> c.flags[InvalidOperation] = 0 +>>> print c.flags[InvalidOperation] 0 >>> print c.divide(Decimal(0), Decimal(0)) Traceback (most recent call last): ... ... ... -DivisionUndefined: 0 / 0 ->>> print c.flags[DivisionUndefined] +InvalidOperation: 0 / 0 +>>> print c.flags[InvalidOperation] 1 ->>> c.flags[DivisionUndefined] = 0 ->>> c.trap_enablers[DivisionUndefined] = False +>>> c.flags[InvalidOperation] = 0 +>>> c.trap_enablers[InvalidOperation] = 0 >>> print c.divide(Decimal(0), Decimal(0)) NaN ->>> print c.flags[DivisionUndefined] +>>> print c.flags[InvalidOperation] 1 >>> """ @@ -152,7 +152,7 @@ ALWAYS_ROUND = 'ALWAYS_ROUND' # Every operation rounds at end. #Errors class DecimalException(ArithmeticError): - """Base exception class, defines default things. + """Base exception class. Used exceptions derive from this. If an exception derives from another exception besides this (such as @@ -160,12 +160,6 @@ class DecimalException(ArithmeticError): called if the others are present. This isn't actually used for anything, though. - Attributes: - - default -- If the context is basic, the trap_enablers are set to - this by default. Extended contexts start out with them set - to 0, regardless. - handle -- Called when context._raise_error is called and the trap_enabler is set. First argument is self, second is the context. More arguments can be given, those being after @@ -176,7 +170,6 @@ class DecimalException(ArithmeticError): To define a new exception, it should be sufficient to have it derive from DecimalException. """ - default = 1 def handle(self, context, *args): pass @@ -288,7 +281,7 @@ class Inexact(DecimalException): The inexact signal may be tested (or trapped) to determine if a given operation (or sequence of operations) was inexact. """ - default = 0 + pass class InvalidContext(InvalidOperation): """Invalid context. Unknown rounding, for example. @@ -315,7 +308,7 @@ class Rounded(DecimalException): The rounded signal may be tested (or trapped) to determine if a given operation (or sequence of operations) caused a loss of precision. """ - default = 0 + pass class Subnormal(DecimalException): """Exponent < Emin before rounding. @@ -382,19 +375,15 @@ class Underflow(Inexact, Rounded, Subnormal): In all cases, Inexact, Rounded, and Subnormal will also be raised. """ +# List of public traps and flags +Signals = [Clamped, DivisionByZero, Inexact, Overflow, Rounded, + Underflow, InvalidOperation, Subnormal] -def _filterfunc(obj): - """Returns true if a subclass of DecimalException""" - try: - return issubclass(obj, DecimalException) - except TypeError: - return False - -#Signals holds the exceptions -Signals = filter(_filterfunc, globals().values()) - -del _filterfunc - +# Map conditions (per the spec) to signals +_condition_map = {ConversionSyntax:InvalidOperation, + DivisionImpossible:InvalidOperation, + DivisionUndefined:InvalidOperation, + InvalidContext:InvalidOperation} ##### Context Functions ####################################### @@ -2168,7 +2157,7 @@ class Context(object): return nc __copy__ = copy - def _raise_error(self, error, explanation = None, *args): + def _raise_error(self, condition, explanation = None, *args): """Handles an error If the flag is in _ignored_flags, returns the default response. @@ -2176,6 +2165,7 @@ class Context(object): trap_enabler is set, it reaises the exception. Otherwise, it returns the default value after incrementing the flag. """ + error = _condition_map.get(condition, condition) if error in self._ignored_flags: #Don't touch the flag return error().handle(self, *args) @@ -2183,7 +2173,7 @@ class Context(object): self.flags[error] += 1 if not self.trap_enablers[error]: #The errors define how to handle themselves. - return error().handle(self, *args) + return condition().handle(self, *args) # Errors should only be risked on copies of the context #self._ignored_flags = [] @@ -2207,6 +2197,11 @@ class Context(object): for flag in flags: self._ignored_flags.remove(flag) + def __hash__(self): + """A Context cannot be hashed.""" + # We inherit object.__hash__, so we must deny this explicitly + raise TypeError, "Cannot hash a Context." + def Etiny(self): """Returns Etiny (= Emin - prec + 1)""" return int(self.Emin - self.prec + 1) |