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====== Function COPY-READTABLE ====== ====Syntax==== * **copy-readtable** ''&optional'' //from-readtable// //to-readtable// → //readtable// ====Arguments and Values==== * //from-readtable// - a //[[CL:Glossary:readtable designator]]//. The default is the //[[CL:Glossary:current readtable]]//. * //to-readtable// - a //[[CL:Glossary:readtable]]// or **[[CL:Constant Variables:nil]]**. The default is **[[CL:Constant Variables:nil]]**. * //readtable// - the //to-readtable// if it is //[[CL:Glossary:non-nil]]//, or else a //[[CL:Glossary:fresh]]// //[[CL:Glossary:readtable]]//. ====Description==== **copy-readtable** copies //from-readtable//. If //to-readtable// is **[[CL:Constant Variables:nil]]**, a new //[[CL:Glossary:readtable]]// is created and returned. Otherwise the //[[CL:Glossary:readtable]]// specified by //to-readtable// is modified and returned. **copy-readtable** copies the setting of **[[CL:Functions:readtable-case]]**. ====Examples==== <blockquote> ([[CL:Macros:defparameter]] zvar 123) <r>ZVAR </r> ([[CL:Macros:defparameter]] *backup-table* (copy-readtable)) <r>*BACKUP-TABLE*</r> ([[CL:Functions:set-syntax-from-char]] #\z #\' *backup-table*) <r>[[CL:Constant Variables:T]] </r> zvar <r>123 </r> (copy-readtable *backup-table* [[CL:Variables:star-readtable-star|*readtable*]]) <r>#<READTABLE 614000277> </r> zvar <r>VAR </r> ([[CL:Macros:setf]] [[CL:Variables:star-readtable-star|*readtable*]] (copy-readtable)) <r>#<READTABLE 46210223> </r> zvar <r>VAR </r> ([[CL:Macros:setf]] [[CL:Variables:star-readtable-star|*readtable*]] (copy-readtable [[CL:Constant Variables:nil]])) <r>#<READTABLE 46302670> </r> zvar <r>123 </r> </blockquote> ====Affected By==== None. ====Exceptional Situations==== None. ====See Also==== * **[[CL:Types:readtable|System Class READTABLE]]** * **[[CL:Variables:star-readtable-star|Variable *READTABLE*]]** ====Notes==== <blockquote> ([[CL:Macros:setf]] [[CL:Variables:star-readtable-star|*readtable*]] (copy-readtable [[CL:Constant Variables:nil]])) </blockquote> restores the input syntax to standard Common Lisp syntax, even if the //[[CL:Glossary:initial readtable]]// has been clobbered (assuming it is not so badly clobbered that you cannot type in the above expression). On the other hand, <blockquote> ([[CL:Macros:setf]] [[CL:Variables:star-readtable-star|*readtable*]] (copy-readtable)) </blockquote> replaces the current //[[CL:Glossary:readtable]]// with a copy of itself. This is useful if you want to save a copy of a readtable for later use, protected from alteration in the meantime. It is also useful if you want to locally bind the readtable to a copy of itself, as in: <blockquote> (let (([[CL:Variables:star-readtable-star|*readtable*]] (copy-readtable))) ...) </blockquote> \issue{READ-CASE-SENSITIVITY:READTABLE-KEYWORDS}