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(guile.info)Property Lists

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Property Lists
==============

Every object in the system can have a "property list" that may be used
for information about that object.  For example, a function may have a
property list that includes information about the source file in which
it is defined.

Property lists are implemented as assq lists (Note: Association
Lists).

Currently, property lists are implemented differently for procedures and
closures than for other kinds of objects.  Therefore, when manipulating
a property list associated with a procedure object, use the `procedure'
functions; otherwise, use the `object' functions.

 - primitive: object-properties obj
 - primitive: procedure-properties obj
     Return OBJ's property list.

 - primitive: set-object-properties! obj plist
 - primitive: set-procedure-properties! obj alist
     Set OBJ's property list to ALIST.

 - primitive: object-property obj key
 - primitive: procedure-property obj key
     Return the property of OBJ with name KEY.

 - primitive: set-object-property! obj key val
 - primitive: set-procedure-property! obj key value
     In OBJ's property list, set the property named KEY to VALUE.

[Interface bug:  there should be a second level of interface in which
the user provides a "property table" that is possibly private.]