Issue: COPY-SYMBOL-PRINT-NAME

[chapman%aitg.DEC@decwrl.dec.com]

!
 From:	DECWRL::AITG::CHAPMAN  "8-Mar-89 0822 GMT"  8-MAR-1989 08:32:30.91
To:	cl-cleanup@sail.stanford.edu, skona%csilvax@hub.ucsb.edu
CC:	
Subj:	Issue: COPY-SYMBOL-PRINT-NAME

Issue:        COPY-SYMBOL-PRINT-NAME
References:   COPY-SYMBOL (p. 169)
Category:     CLARIFICATION
Edit history: 1-MAR-89, Version 1 by Chapman
              15-MAR-89, Version 2 by Chapman
 
Problem Description:
 
The description of COPY-SYMBOL states that it "returns a new uninterned
symbol with the same print name as sym (its first argument)". The words
"the same as" are not defined in CLtL. Do they mean EQ, EQUAL, ...?
 
Proposal (COPY-SYMBOL-PRINT-NAME:EQUAL)
 
The description of COPY-SYMBOL should read as follows:
"COPY-SYMBOL returns an uninterned
symbol whose print name is STRING= to
the print name of the symbol that is the first argument to COPY-SYMBOL."
 
Suggested implementation note:
The string should not be copied unnecessarily. In this case, the uninterned
symbol's print name would be EQ to the print name of the argument symbol.
 
Rationale:
 
This clarification resolves any possibility of ambiguity.
 
Current Practice:
 
Medley did this: the symbol names didn't really have a string header and
some symbol names (the "initial symbols" ) had a different place for
storing the actual characters than symbols created later. Unfortunately,
that means that SYMBOL-NAME has to CONS.
It wasn't so much a problem for Interlisp since most of the "string"
functions in Interlisp will take symbols, but in Common Lisp, it is a
performance hit. Poor design, but there's no reason to require SYMBOL-NAME
to return EQ strings. 
In this case, the strings aren't EQ even though the string characters are
shared. (Think of it as strings displaced to a shared area.)
 
 
Adoption Cost:
 
?
 
Benefits:
 
Less ambiguity in the specification, and potentially more portable code.
 
Conversion Cost:
 
?
 
Aesthetics:
 
None.
 
Discussion: