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ANSI Common Lisp  10 Symbols 10.2 Dictionary of Symbols
- Syntax:
-
gentemp
&optional prefix package
 new-symbol
- Arguments and Values:
-
prefix - a string.
The default is "T".
package - a package designator.
The default is the current package.
new-symbol - a fresh, interned symbol.
- Description:
-
gentemp creates and returns a fresh symbol,
interned in the indicated package.
The symbol is guaranteed to be one that was not previously
accessible in package.
It is neither bound nor fbound, and has a null
property list.
The name of the new-symbol is the concatenation
of the prefix and a suffix, which is taken from an internal
counter used only by gentemp. (If a symbol by that name
is already accessible in package, the counter is incremented as
many times as is necessary to produce a name that is not already the
name of a symbol accessible in package.)
- Examples:
-
(gentemp) T1298
(gentemp "FOO") FOO1299
(find-symbol "FOO1300") NIL, NIL
(gentemp "FOO") FOO1300
(find-symbol "FOO1300") FOO1300, :INTERNAL
(intern "FOO1301") FOO1301, :INTERNAL
(gentemp "FOO") FOO1302
(gentemp) T1303
- Side Effects:
-
Its internal counter is incremented one or more times.
Interns the new-symbol in package.
- Affected By:
-
The current state of its internal counter, and
the current state of the package.
- Exceptional Situations:
-
Should signal an error of type type-error if prefix is not a string.
Should signal an error of type type-error if package is not a package designator.
- See Also:
-
gensym
- Notes:
-
The function gentemp is deprecated.
If package is the keyword package,
the result is an external symbol of package.
Otherwise, the result is an internal symbol of package.
The gentemp internal counter is independent of
*gensym-counter*, the counter used by gensym.
There is no provision for accessing the gentemp internal counter.
Just because gentemp creates a symbol which did not
previously exist does not mean that such a symbol might not be
seen in the future (e.g., in a data file - perhaps even created by the
same program in another session). As such, this symbol is not truly
unique in the same sense as a gensym would be. In particular,
programs which do automatic code generation should be careful not to
attach global attributes to such generated symbols (e.g.,
special declarations) and then write them into a file
because such global attributes might, in a different session, end up
applying to other symbols that were automatically generated on
another day for some other purpose.
- Allegro CL Implementation Details:
-
None.
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