gyro@kestrel.edu (Scott Layson Burson) (03/28/91)
So here I am implementing an Ada front end (for an analysis system,
not a compiler) and I'm working on use clauses, and I seem to have
found a case which is not mentioned in the manual, nor can I find any
mention of it in the commentaries. To wit: what happens if a use
clause appears among the basic declarative items in the visible part
of a package specification? Do the identifiers made directly visible
by the use clause become part of the package's visible declarations?
Now, it seems to me that either:
1) The use clause does augment the package's visible declarations,
and this is not the slightest bit problematic -- the various
existing rules cover the fine points of the situation perfectly
well. This seems unlikely, because it's the kind of thing the LRM
would typically include a helpful note about.
2) Despite the fact that the syntax allows use clauses in visible
parts of packages, nobody but me has ever actually thought of
putting one there. This seems unlikely because of the amount of
time people have spent poring over the specification and the
number of extant implementations.
3) The relevant rules are in the LRM or commentaries somewhere, but
I haven't found them. This seems unlikely because there aren't
many places in the manual where I would expect to find such rules,
and grepping through the commentaries turns up a short list of
instances of "use clause", among which I have found no reference
to this possibility.
Can anyone help me out?
-- Scott Burson
Gyro@Reasoning.COMstluka@software.org (Fred Stluka) (03/29/91)
In article <1991Mar27.200047.21167@kestrel.edu> Gyro@Reasoning.COM writes: > ... To wit: what happens if a use > clause appears among the basic declarative items in the visible part > of a package specification? Do the identifiers made directly visible > by the use clause become part of the package's visible declarations? No. The identifiers are only made visible to the "scope" of the use clause, which does not include other packages which "with" the package containing the use clause. Section 8.4(4) says: In order to define which declarations are made directly visible at a given place by use clauses, consider the set of packages named by all use clauses whose scopes enclose this place... ^^^^^^^ The "scope" of a use clause is defined in 8.4(3) as: For each use clause, there is a certain region of text called the "scope" of the use clause. This region starts immediately after the use clause. If the use clause is a declarative item of some declarative region, the scope of the clause extends to the end of the declarative region. ... --Fred -- Fred Stluka Internet: stluka@software.org Software Productivity Consortium UUNET: ...!uunet!software!stluka 2214 Rock Hill Rd, Herndon VA 22070 USA