63 lines
5.9 KiB
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63 lines
5.9 KiB
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<TITLE>CLHS: Function UNINTERN</TITLE>
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<A NAME="unintern"><I>Function</I> <B>UNINTERN</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>unintern</B> <I>symbol <TT>&optional</TT> package</I> => <I>generalized-boolean</I><P>
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<P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>symbol</I>---a <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbol</I></A>. <P>
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<I>package</I>---a <A REL=DEFINITION HREF="26_glo_p.htm#package_designator"><I>package designator</I></A>. The default is the <A REL=DEFINITION HREF="26_glo_c.htm#current_package"><I>current package</I></A>. <P>
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<I>generalized-boolean</I>---a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<P><B>Description:</B><P>
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<A REL=DEFINITION HREF="#unintern"><B>unintern</B></A> removes <I>symbol</I> from <I>package</I>. If <I>symbol</I> is <A REL=DEFINITION HREF="26_glo_p.htm#present"><I>present</I></A> in <I>package</I>, it is removed from <I>package</I> and also from <I>package</I>'s <A REL=DEFINITION HREF="26_glo_s.htm#shadowing_symbols_list"><I>shadowing symbols list</I></A> if it is present there. If <I>package</I> is the <A REL=DEFINITION HREF="26_glo_h.htm#home_package"><I>home package</I></A> for <I>symbol</I>, <I>symbol</I> is made to have no <A REL=DEFINITION HREF="26_glo_h.htm#home_package"><I>home package</I></A>. <I>Symbol</I> may continue to be <A REL=DEFINITION HREF="26_glo_a.htm#accessible"><I>accessible</I></A> in <I>package</I> by inheritance. <P>
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Use of <A REL=DEFINITION HREF="#unintern"><B>unintern</B></A> can result in a <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbol</I></A> that has no recorded <A REL=DEFINITION HREF="26_glo_h.htm#home_package"><I>home package</I></A>, but that in fact is <A REL=DEFINITION HREF="26_glo_a.htm#accessible"><I>accessible</I></A> in some <A REL=DEFINITION HREF="26_glo_p.htm#package"><I>package</I></A>. Common Lisp does not check for this pathological case, and such <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbols</I></A> are always printed preceded by <TT>#:</TT>. <P>
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<A REL=DEFINITION HREF="#unintern"><B>unintern</B></A> returns <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A> if it removes <I>symbol</I>, and <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> otherwise. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(in-package "COMMON-LISP-USER") => #<PACKAGE "COMMON-LISP-USER">
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(setq temps-unpack (intern "UNPACK" (make-package 'temp))) => TEMP::UNPACK
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(unintern temps-unpack 'temp) => T
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(find-symbol "UNPACK" 'temp) => NIL, NIL
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temps-unpack => #:UNPACK
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B><P>
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<P>
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<A REL=DEFINITION HREF="#unintern"><B>unintern</B></A> changes the state of the package system in such a way that the consistency rules do not hold across the change. <P>
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<P><B>Affected By:</B><P>
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Current state of the package system. <P>
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<P><B>Exceptional Situations:</B><P>
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Giving a shadowing symbol to <A REL=DEFINITION HREF="#unintern"><B>unintern</B></A> can uncover a name conflict that had previously been resolved by the shadowing. If package A uses packages B and C, A contains a shadowing symbol <TT>x</TT>, and B and C each contain external symbols named <TT>x</TT>, then removing the shadowing symbol <TT>x</TT> from A will reveal a name conflict between <TT>b:x</TT> and <TT>c:x</TT> if those two <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbols</I></A> are distinct. In this case <A REL=DEFINITION HREF="#unintern"><B>unintern</B></A> will signal an error. <P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=CHILD HREF="11_a.htm">Section 11.1 (Package Concepts)</A> <P>
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<P><B>Notes:</B> None.
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<P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issue</A>, <I>not part of the specification</I>, applies to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss254.htm">PACKAGE-FUNCTION-CONSISTENCY:MORE-PERMISSIVE</A><P></UL><HR>
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