Interpretation of shadowing

["Dieter Kolb" <unido!ztivax!kolb@seismo.CSS.GOV>]

CLtL describes in section 11.5, page 180 a name conflict problem by 
applying the function use-package. The name conflict is between a symbol 
directly present in the using package and an external symbol of the used 
package. This name conflict may be resolved in favor of the symbol 
directly present in the using package by making it a shadowing symbol. 

However, CLtL gives no advice how that should be done.

In our understanding the function shadow should be used to resolve this 
name conflict. 

However the function shadow has no effect, if the symbol is already 
present in the package (CLtL, section 11.7). So, following CLtL, this 
could not be the solution. Therefore, we investigated some other CL 
implementations:

Lucid Common LISP on Apollo DOMAIN as well as Xerox LISP:
The name conflict can be resolved by using the function shadowing-import

SPICE LISP: 
The functionality of the function shadow in SPICE LISP is extended. 
shadow works also if the symbol is already present. So, the name 
conflict can be resolved by using the function shadow. (However, shadow 
works different as described in CLtL.)

Kyoto Common Lisp on VAX:
shadow works as described in CLtL. The name conflict cannot be resolved 
in this system.

How should CLtL be interpreted with respect to this problem?


Dieter Kolb