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#############################################################################
##
#W attr.gd GAP library Steve Linton
##
#H @(#)$Id: attr.gd,v 4.7 2002/04/15 10:04:26 sal Exp $
##
#Y Copyright (C) 1996, Lehrstuhl D fuer Mathematik, RWTH Aachen, Germany
#Y (C) 1998 School Math and Comp. Sci., University of St. Andrews, Scotland
#Y Copyright (C) 2002 The GAP Group
Revision.attr_gd :=
"@(#)$Id: attr.gd,v 4.7 2002/04/15 10:04:26 sal Exp $";
#1
## The normal behaviour of attributes (when called with just one argument)
## is that once a method has been selected and executed, and has returned a
## value the setter of the attribute is called, to (possibly) store the
## computed value. In special circumstances, this behaviour can be altered
## dynamically on an attribute-by-attribute basis, using the functions
## `DisableAttributeValueStoring' and `EnableAttributeValueStoring'.
##
## In general, the code in the library assumes, for efficiency, but not for
## correctness, that attribute values *will* be stored (in suitable
## objects), so disabling storing may cause substantial computations to be
## repeated.
##
#############################################################################
##
#V InfoAttributes . . . info class for reporting on attribute tweaking
##
## This info class (together with `InfoWarning'; see~"InfoWarning") is used
## for messages about attribute storing being disabled (at level 2) or
## enabled (level 3). It may be used in the future for other messages
## concerning changes to attribute behaviour.
##
DeclareInfoClass("InfoAttributes");
#############################################################################
##
#F EnableAttributeValueStoring( <attr> ) tell attr. to resume storing values
##
## enables the usual call of `Setter( <attr> )' when a method for <attr>
## returns a value. In consequence the values may be stored. This will
## usually have no effect unless `DisableAttributeValueStoring' has
## previously been used for <attr>. Note that <attr> must be an attribute
## and *not* a property.
##
DeclareGlobalFunction("EnableAttributeValueStoring");
#############################################################################
##
#F DisableAttributeValueStoring( <attr> ) tell attr. to stop storing values
##
## disables the usual call of `Setter( <attr> )' when a method for <attr>
## returns a value. In consequence the values will never be stored. Note
## that <attr> must be an attribute and *not* a property.
##
DeclareGlobalFunction("DisableAttributeValueStoring");
#############################################################################
##
#E
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