[Python-checkins] python/dist/src/Lib decimal.py,1.12,1.13

[rhettinger at users.sourceforge.net]

Update of /cvsroot/python/python/dist/src/Lib
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv28156/Lib

Modified Files:
	decimal.py 
Log Message:
Module and tests:
* Map conditions to related signals.
* Make contexts unhashable.
* Eliminate used "default" attribute in exception definitions.
* Eliminate the _filterfunc in favor of a straight list.

Docs:
* Eliminate documented references to conditions that are not signals.
* Eliminate parenthetical notes such as "1/0 --> Inf" which are no
  longer true with the new defaults.



Index: decimal.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/decimal.py,v
retrieving revision 1.12
retrieving revision 1.13
diff -C2 -d -r1.12 -r1.13
*** decimal.py	8 Jul 2004 00:49:18 -0000	1.12
--- decimal.py	9 Jul 2004 10:02:51 -0000	1.13
***************
*** 79,92 ****
  DivisionByZero: x / 0
  >>> c = Context()
! >>> c.trap_enablers[DivisionUndefined] = 0
! >>> print c.flags[DivisionUndefined]
  0
  >>> c.divide(Decimal(0), Decimal(0))
  Decimal("NaN")
! >>> c.trap_enablers[DivisionUndefined] = 1
! >>> print c.flags[DivisionUndefined]
  1
! >>> c.flags[DivisionUndefined] = 0
! >>> print c.flags[DivisionUndefined]
  0
  >>> print c.divide(Decimal(0), Decimal(0))
--- 79,92 ----
  DivisionByZero: x / 0
  >>> c = Context()
! >>> c.trap_enablers[InvalidOperation] = 0
! >>> print c.flags[InvalidOperation]
  0
  >>> c.divide(Decimal(0), Decimal(0))
  Decimal("NaN")
! >>> c.trap_enablers[InvalidOperation] = 1
! >>> print c.flags[InvalidOperation]
  1
! >>> c.flags[InvalidOperation] = 0
! >>> print c.flags[InvalidOperation]
  0
  >>> print c.divide(Decimal(0), Decimal(0))
***************
*** 95,106 ****
    ...
    ...
! DivisionUndefined: 0 / 0
! >>> print c.flags[DivisionUndefined]
  1
! >>> c.flags[DivisionUndefined] = 0
! >>> c.trap_enablers[DivisionUndefined] = False
  >>> print c.divide(Decimal(0), Decimal(0))
  NaN
! >>> print c.flags[DivisionUndefined]
  1
  >>>
--- 95,106 ----
    ...
    ...
! InvalidOperation: 0 / 0
! >>> print c.flags[InvalidOperation]
  1
! >>> c.flags[InvalidOperation] = 0
! >>> c.trap_enablers[InvalidOperation] = 0
  >>> print c.divide(Decimal(0), Decimal(0))
  NaN
! >>> print c.flags[InvalidOperation]
  1
  >>>
***************
*** 153,157 ****
  
  class DecimalException(ArithmeticError):
!     """Base exception class, defines default things.
  
      Used exceptions derive from this.
--- 153,157 ----
  
  class DecimalException(ArithmeticError):
!     """Base exception class.
  
      Used exceptions derive from this.
***************
*** 161,170 ****
      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
--- 161,164 ----
***************
*** 177,181 ****
      from DecimalException.
      """
-     default = 1
      def handle(self, context, *args):
          pass
--- 171,174 ----
***************
*** 289,293 ****
      operation (or sequence of operations) was inexact.
      """
!     default = 0
  
  class InvalidContext(InvalidOperation):
--- 282,286 ----
      operation (or sequence of operations) was inexact.
      """
!     pass
  
  class InvalidContext(InvalidOperation):
***************
*** 316,320 ****
      operation (or sequence of operations) caused a loss of precision.
      """
!     default = 0
  
  class Subnormal(DecimalException):
--- 309,313 ----
      operation (or sequence of operations) caused a loss of precision.
      """
!     pass
  
  class Subnormal(DecimalException):
***************
*** 383,399 ****
      """
  
  
! 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
! 
  
  ##### Context Functions #######################################
--- 376,388 ----
      """
  
+ # List of public traps and flags
+ Signals = [Clamped, DivisionByZero, Inexact, Overflow, Rounded,
+            Underflow, InvalidOperation, Subnormal]
  
! # Map conditions (per the spec) to signals
! _condition_map = {ConversionSyntax:InvalidOperation,
!                   DivisionImpossible:InvalidOperation,
!                   DivisionUndefined:InvalidOperation,
!                   InvalidContext:InvalidOperation}
  
  ##### Context Functions #######################################
***************
*** 2169,2173 ****
      __copy__ = copy
  
!     def _raise_error(self, error, explanation = None, *args):
          """Handles an error
  
--- 2158,2162 ----
      __copy__ = copy
  
!     def _raise_error(self, condition, explanation = None, *args):
          """Handles an error
  
***************
*** 2177,2180 ****
--- 2166,2170 ----
          the default value after incrementing the flag.
          """
+         error = _condition_map.get(condition, condition)
          if error in self._ignored_flags:
              #Don't touch the flag
***************
*** 2184,2188 ****
          if not self.trap_enablers[error]:
              #The errors define how to handle themselves.
!             return error().handle(self, *args)
  
          # Errors should only be risked on copies of the context
--- 2174,2178 ----
          if not self.trap_enablers[error]:
              #The errors define how to handle themselves.
!             return condition().handle(self, *args)
  
          # Errors should only be risked on copies of the context
***************
*** 2208,2211 ****
--- 2198,2206 ----
              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)"""