File psl-1983/help/package.hlp artifact 6b365538f9 part of check-in 3af273af29


The Utah Package System (UPS)
----------------------------

A preliminary multi-name space capability is available for testing.
This is a loadable option (Load Package).

Syntactically, an id now becomes a multipart name, "PACKAGE\localId" which
directs the INTERN part of token scanning to start searching a PATH in a
linked Oblist structure from PACKAGE, itself an id accessible in the
"CurrentPackage".  The Print name is still "localId", but an additional
field in each id, the Package Cell, records PACKAGE.  A modified Prin1 and
Prin2 access this field.  The Root of the tree is GLOBAL, indicated by \.
Thus \ID is guaranteed in the root (in fact the existing Oblist).

PAKAGE.RED defines the following Fluids:
        \CurrentPackage!*		 %. Start of Search Path
        \PackageNames!*                  %. List of ALL package names

\CurrentPackage!* is rebound in the Token Scanner on encountering a "\".

The following functions should be used:

  \CreatePackage(Name,FatherPackage) which creates a convenient size
                                     hashtable
        
  \PackageP(name)

  \SetPackage(name)

  \PathInternP({id, string})       Searchs from CurrentPackage!*
  \PathIntern({id, string})        Lookup or insert  
  \PathRemob({id, string})         Remobs, puts in NIL package
  \PathMapObl(function)            Applies to ALL ids in path

  \LocalInternP({id, string})       Searchs in CurrentPackage!*
  \LocalIntern({id, string})        Lookup or insert  in CurrentPackage!*
  \LocalRemob({id, string})         Remobs, puts in NIL package
  \LocalMapObl(function)            Applies to ALL ids in CurrentPackage!*

Note that if a string is used, it CANNOT include the \.  Also, since most
id's are "RAISED" on input, be careful.

Current INTERN etc are \PathIntern, etc.



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