98 lines
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98 lines
8.9 KiB
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<!-- 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 TYPE-OF</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="f_subtpp.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_types_.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_typep.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<A NAME="type-of"><I>Function</I> <B>TYPE-OF</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>type-of</B> <I>object</I> => <I>typespec</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>object</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. <P>
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<I>typespec</I>---a <A REL=DEFINITION HREF="26_glo_t.htm#type_specifier"><I>type specifier</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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<P>
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Returns a <A REL=DEFINITION HREF="26_glo_t.htm#type_specifier"><I>type specifier</I></A>, <I>typespec</I>, for a <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> that has the <I>object</I> as an <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>element</I></A>. The <I>typespec</I> satisfies the following: <P>
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<P><DL><P>
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<DT>1. For any <I>object</I> that is an <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>element</I></A> of some <A REL=DEFINITION HREF="26_glo_b.htm#built-in_type"><I>built-in type</I></A>: <P><DD>
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<P><DL><DT>a. the <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> returned is a <A REL=DEFINITION HREF="26_glo_r.htm#recognizable_subtype"><I>recognizable subtype</I></A> of that <A REL=DEFINITION HREF="26_glo_b.htm#built-in_type"><I>built-in type</I></A>. <P><DD>
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<DT>b. the <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> returned does not involve <TT>and</TT>, <TT>eql</TT>, <TT>member</TT>, <TT>not</TT>, <TT>or</TT>, <TT>satisfies</TT>, or <TT>values</TT>. <P><DD></DL><P>
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<DT>2. For all <I>objects</I>, <TT>(typep </TT><I>object</I><TT> (type-of </TT><I>object</I><TT>))</TT> returns <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A>. Implicit in this is that <A REL=DEFINITION HREF="26_glo_t.htm#type_specifier"><I>type specifiers</I></A> which are not valid for use with <A REL=DEFINITION HREF="f_typep.htm#typep"><B>typep</B></A>, such as the <A REL=DEFINITION HREF="26_glo_l.htm#list"><I>list</I></A> form of the <A REL=DEFINITION HREF="s_fn.htm#function"><B>function</B></A> <A REL=DEFINITION HREF="26_glo_t.htm#type_specifier"><I>type specifier</I></A>, are never returned by <A REL=DEFINITION HREF="#type-of"><B>type-of</B></A>. <P><DD>
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<DT>3. The <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> returned by <A REL=DEFINITION HREF="#type-of"><B>type-of</B></A> is always a <A REL=DEFINITION HREF="26_glo_r.htm#recognizable_subtype"><I>recognizable subtype</I></A> of the <A REL=DEFINITION HREF="26_glo_c.htm#class"><I>class</I></A> returned by <A REL=DEFINITION HREF="f_clas_1.htm#class-of"><B>class-of</B></A>. That is, <P><DD>
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<PRE>
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(subtypep (type-of object) (class-of object)) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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</PRE>
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</TT> <P>
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<DT>4. For <I>objects</I> of metaclass <A REL=DEFINITION HREF="t_stu_cl.htm#structure-class"><B>structure-class</B></A> or <A REL=DEFINITION HREF="t_std_cl.htm#standard-class"><B>standard-class</B></A>, and for <A REL=DEFINITION HREF="26_glo_c.htm#condition"><I>conditions</I></A>, <A REL=DEFINITION HREF="#type-of"><B>type-of</B></A> returns the <A REL=DEFINITION HREF="26_glo_p.htm#proper_name"><I>proper name</I></A> of the <A REL=DEFINITION HREF="26_glo_c.htm#class"><I>class</I></A> returned by <A REL=DEFINITION HREF="f_clas_1.htm#class-of"><B>class-of</B></A> if it has a <A REL=DEFINITION HREF="26_glo_p.htm#proper_name"><I>proper name</I></A>, and otherwise returns the <A REL=DEFINITION HREF="26_glo_c.htm#class"><I>class</I></A> itself. In particular, for <I>objects</I> created by the constructor function of a structure defined with <A REL=DEFINITION HREF="m_defstr.htm#defstruct"><B>defstruct</B></A> without a <TT>:type</TT> option, <A REL=DEFINITION HREF="#type-of"><B>type-of</B></A> returns the structure name; and for <I>objects</I> created by <A REL=DEFINITION HREF="f_mk_cnd.htm#make-condition"><B>make-condition</B></A>, the <I>typespec</I> is the <A REL=DEFINITION HREF="26_glo_n.htm#name"><I>name</I></A> of the <A REL=DEFINITION HREF="26_glo_c.htm#condition"><I>condition</I></A> <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A>. <P><DD>
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<DT>5. For each of the <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>types</I></A> <A REL=DEFINITION HREF="t_short_.htm#short-float"><B>short-float</B></A>, <A REL=DEFINITION HREF="t_short_.htm#single-float"><B>single-float</B></A>, <A REL=DEFINITION HREF="t_short_.htm#double-float"><B>double-float</B></A>, or <A REL=DEFINITION HREF="t_short_.htm#long-float"><B>long-float</B></A> of which the <I>object</I> is an <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>element</I></A>, the <I>typespec</I> is a <A REL=DEFINITION HREF="26_glo_r.htm#recognizable_subtype"><I>recognizable subtype</I></A> of that <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A>. <P><DD>
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<P></DL><P>
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<P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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</PRE>
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</TT> <P>
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<PRE>
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(type-of 'a) => SYMBOL
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(type-of '(1 . 2))
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=> CONS
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OR=> (CONS FIXNUM FIXNUM)
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(type-of #c(0 1))
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=> COMPLEX
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OR=> (COMPLEX INTEGER)
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(defstruct temp-struct x y z) => TEMP-STRUCT
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(type-of (make-temp-struct)) => TEMP-STRUCT
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(type-of "abc")
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=> STRING
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OR=> (STRING 3)
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(subtypep (type-of "abc") 'string) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(type-of (expt 2 40))
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=> BIGNUM
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OR=> INTEGER
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OR=> (INTEGER 1099511627776 1099511627776)
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OR=> SYSTEM::TWO-WORD-BIGNUM
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OR=> FIXNUM
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(subtypep (type-of 112312) 'integer) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>, <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(defvar *foo* (make-array 5 :element-type t)) => *FOO*
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(class-name (class-of *foo*)) => VECTOR
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(type-of *foo*)
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=> VECTOR
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OR=> (VECTOR T 5)
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</PRE>
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</TT> <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> None.
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<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_ar_ele.htm#array-element-type"><B>array-element-type</B></A>, <A REL=DEFINITION HREF="f_clas_1.htm#class-of"><B>class-of</B></A>, <A REL=DEFINITION HREF="m_defstr.htm#defstruct"><B>defstruct</B></A>, <A REL=DEFINITION HREF="m_tpcase.htm#typecase"><B>typecase</B></A>, <A REL=DEFINITION HREF="f_typep.htm#typep"><B>typep</B></A>, <A REL=CHILD HREF="04_b.htm">Section 4.2 (Types)</A> <P>
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<P><B>Notes:</B><P>
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<P>
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Implementors are encouraged to arrange for <A REL=DEFINITION HREF="#type-of"><B>type-of</B></A> to return a portable value. <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/iss350.htm">TYPE-OF-AND-PREDEFINED-CLASSES:TYPE-OF-HANDLES-FLOATS</A><LI> <A REL=CHILD HREF="../Issues/iss351.htm">TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND</A><LI> <A REL=CHILD HREF="../Issues/iss352.htm">TYPE-OF-UNDERCONSTRAINED:ADD-CONSTRAINTS</A><P></UL><HR>
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<A REL=COPYRIGHT HREF="../Front/Help.htm#Legal"><I>Copyright 1996-2005, LispWorks Ltd. All rights reserved.</I></A><P>
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