84 lines
5.7 KiB
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84 lines
5.7 KiB
HTML
<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<TITLE>CLHS: Function FBOUNDP</TITLE>
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<A NAME="fboundp"><I>Function</I> <B>FBOUNDP</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>fboundp</B> <I>name</I> => <I>generalized-boolean</I><P>
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<P>
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<P><B>Pronunciation:</B><P>
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<P>
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[,ef'bandpee] <P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>name</I>---a <A REL=DEFINITION HREF="26_glo_f.htm#function_name"><I>function name</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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<P>
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Returns <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A> if <I>name</I> is <A REL=DEFINITION HREF="26_glo_f.htm#fbound"><I>fbound</I></A>; otherwise, returns <A REL=DEFINITION HREF="26_glo_f.htm#false"><I>false</I></A>. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(fboundp 'car) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(fboundp 'nth-value) => <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>
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(fboundp 'with-open-file) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(fboundp 'unwind-protect) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(defun my-function (x) x) => MY-FUNCTION
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(fboundp 'my-function) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(let ((saved-definition (symbol-function 'my-function)))
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(unwind-protect (progn (fmakunbound 'my-function)
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(fboundp 'my-function))
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(setf (symbol-function 'my-function) saved-definition)))
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=> <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>
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(fboundp 'my-function) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(defmacro my-macro (x) `',x) => MY-MACRO
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(fboundp 'my-macro) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(fmakunbound 'my-function) => MY-FUNCTION
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(fboundp 'my-function) => <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>
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(flet ((my-function (x) x))
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(fboundp 'my-function)) => <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B> None.
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<P>
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<P><B>Affected By:</B> None.
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<P>
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<P><B>Exceptional Situations:</B><P>
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<P>
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Should signal an error of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <A REL=DEFINITION HREF="e_tp_err.htm#type-error"><B>type-error</B></A> if <I>name</I> is not a <A REL=DEFINITION HREF="26_glo_f.htm#function_name"><I>function name</I></A>. <P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=DEFINITION HREF="f_symb_1.htm#symbol-function"><B>symbol-function</B></A>, <A REL=DEFINITION HREF="f_fmakun.htm#fmakunbound"><B>fmakunbound</B></A>, <A REL=DEFINITION HREF="f_fdefin.htm#fdefinition"><B>fdefinition</B></A> <P>
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<P><B>Notes:</B><P>
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<P>
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It is permissible to call <A REL=DEFINITION HREF="f_symb_1.htm#symbol-function"><B>symbol-function</B></A> on any <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbol</I></A> that is <A REL=DEFINITION HREF="26_glo_f.htm#fbound"><I>fbound</I></A>. <P>
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<A REL=DEFINITION HREF="#fboundp"><B>fboundp</B></A> is sometimes used to ``guard'' an access to the <A REL=DEFINITION HREF="26_glo_f.htm#function_cell"><I>function cell</I></A>, as in:
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<PRE>
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(if (fboundp x) (symbol-function x))
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</PRE>
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</TT> <P>
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Defining a <A REL=DEFINITION HREF="26_glo_s.htm#setf_expander"><I>setf expander</I></A> <I>F</I> does not cause the <A REL=DEFINITION HREF="26_glo_s.htm#setf_function"><I>setf function</I></A> <TT>(setf </TT><I>F</I><TT>)</TT> to become defined. <P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issues</A>, <I>not part of the specification</I>, apply to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss305.htm">SETF-FUNCTIONS-AGAIN:MINIMAL-CHANGES</A><LI> <A REL=CHILD HREF="../Issues/iss174.htm">FUNCTION-NAME:LARGE</A><P></UL><HR>
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