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<H2>Issue DEFMETHOD-DECLARATION-SCOPE Writeup</H2>
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<PRE><B>Issue:</B> <A HREF="iss107.htm">DEFMETHOD-DECLARATION-SCOPE</A><P>
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<B>References:</B> <A REL=DEFINITION HREF="../Body/m_defmet.htm#defmethod"><B>DEFMETHOD</B></A>, <A REL=DEFINITION HREF="../Body/t_generi.htm#generic-function"><B>GENERIC-FUNCTION</B></A>, GENERIC-FLET, GENERIC-LABELS,<P>
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<A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A>, <A REL=DEFINITION HREF="../Body/f_next_m.htm#next-method-p"><B>NEXT-METHOD-P</B></A><P>
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Related issues: <A HREF="iss092.htm">DECLARATION-SCOPE</A><P>
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<A HREF="iss012.htm">ARGUMENT-MISMATCH-ERROR</A><P>
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<A HREF="iss211.htm">LEXICAL-CONSTRUCT-GLOBAL-DEFINITION</A><P>
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<A HREF="iss243.htm">METHOD-INITFORM</A><P>
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<B>Category:</B> CLARIFICATION<P>
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<B>Edit history:</B> v1, 27 Feb 91, Sandra Loosemore<P>
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v2, 28 Feb 91, Sandra Loosemore<P>
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<P>
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<B>Problem description:<P>
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</B><P>
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The body of <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> definition in a <A REL=DEFINITION HREF="../Body/m_defmet.htm#defmethod"><B>DEFMETHOD</B></A>, <A REL=DEFINITION HREF="../Body/t_generi.htm#generic-function"><B>GENERIC-FUNCTION</B></A>,<P>
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GENERIC-FLET, or GENERIC-LABELS form includes an implicit <A REL=DEFINITION HREF="../Body/s_flet_.htm#flet"><B>FLET</B></A> of <P>
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<A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> and <A REL=DEFINITION HREF="../Body/f_next_m.htm#next-method-p"><B>NEXT-METHOD-P</B></A>. Can one put declarations at the <P>
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head of the <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body which apply to these bindings? Do "free" <P>
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declarations (or declarations that don't apply to bindings) at the <P>
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head of the <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body apply to the definitions of these local <P>
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functions? <P>
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<P>
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<P>
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<B>Proposal (DEFMETHOD-DECLARATION-SCOPE:CORRESPONDS-TO-BINDINGS):<P>
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</B><P>
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Clarify that:<P>
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<P>
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(1) Declarations at the head of the <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body that apply to the <P>
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<A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A>'s <A REL=DEFINITION HREF="../Body/a_lambda.htm#lambda"><B>lambda</B></A> variables are treated as "bound" declarations <P>
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whose scope is the same as the corresponding bindings.<P>
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<P>
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(2) Declarations at the head of the <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body that apply to the <P>
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functional bindings of <A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> or <A REL=DEFINITION HREF="../Body/f_next_m.htm#next-method-p"><B>NEXT-METHOD-P</B></A> apply<P>
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to references to those functions within the <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body forms.<P>
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Any outer bindings of these functions and declarations associated <P>
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with those bindings are shadowed within the <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body forms.<P>
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<P>
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(3) The scope of "free" declarations at the head of the <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body <P>
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is the entire <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body (including any implicit local function <P>
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definitions), but excluding initialization forms for the <A REL=DEFINITION HREF="../Body/a_lambda.htm#lambda"><B>lambda</B></A> <P>
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variables.<P>
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<P>
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<B>Rationale:<P>
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</B><P>
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Items (1) and (3) are consistent with the rules from issue <P>
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<A HREF="iss092.htm">DECLARATION-SCOPE</A>.<P>
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<P>
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For item (2), it would be counterintuitive if declarations for <P>
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<A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> or <A REL=DEFINITION HREF="../Body/f_next_m.htm#next-method-p"><B>NEXT-METHOD-P</B></A> that appeared at the head of <P>
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a <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body didn't actually apply to references within the body.<P>
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<P>
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<B>Examples:<P>
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</B><P>
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(1) Must the call to <A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> be NOTINLINE?<P>
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<P>
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(<A REL=DEFINITION HREF="../Body/m_defmet.htm#defmethod"><B>defmethod</B></A> baz (...)<P>
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(<A REL=DEFINITION HREF="../Body/s_declar.htm#declare"><B>declare</B></A> (<A REL=DEFINITION HREF="../Body/d_inline.htm#notinline"><B>notinline</B></A> <A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>call-next-method</B></A>))<P>
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... (<A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>call-next-method</B></A>))<P>
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<P>
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Under proposal CORRESPONDS-TO-BINDINGS, the answer is that the<P>
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declaration does apply. The <A REL=DEFINITION HREF="../Body/d_inline.htm#notinline"><B>NOTINLINE</B></A> declaration applies to<P>
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the local binding of <A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> established within the <P>
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<A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> definition, not to some outer binding that is shadowed by <P>
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the local binding.<P>
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<P>
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(2) Is the definition of <A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> "safe"? (See issue <P>
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<A HREF="iss012.htm">ARGUMENT-MISMATCH-ERROR</A> for why it might matter.)<P>
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<P>
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(<A REL=DEFINITION HREF="../Body/m_defmet.htm#defmethod"><B>defmethod</B></A> baz (...)<P>
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(<A REL=DEFINITION HREF="../Body/s_declar.htm#declare"><B>declare</B></A> (<A REL=DEFINITION HREF="../Body/d_optimi.htm#optimize"><B>optimize</B></A> <A REL=DEFINITION HREF="../Body/d_optimi.htm#safety"><B>safety</B></A>))<P>
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... (<A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>call-next-method</B></A>))<P>
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<P>
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Under proposal CORRESPONDS-TO-BINDINGS, the answer is yes. The<P>
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definition of <A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> is in the scope of the declaration.<P>
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<P>
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(3) Must the call to <A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> be NOTINLINE?<P>
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<P>
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(<A REL=DEFINITION HREF="../Body/m_defmet.htm#defmethod"><B>defmethod</B></A> foo (...)<P>
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(<A REL=DEFINITION HREF="../Body/s_declar.htm#declare"><B>declare</B></A> (<A REL=DEFINITION HREF="../Body/d_inline.htm#notinline"><B>notinline</B></A> <A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>call-next-method</B></A>))<P>
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(generic-flet ((bar (...)<P>
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(:method (...)<P>
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...<P>
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(<A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>call-next-method</B></A>)<P>
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...)))<P>
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...))<P>
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<P>
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Under proposal CORRESPONDS-TO-BINDINGS, the answer is no. The<P>
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<A REL=DEFINITION HREF="../Body/d_inline.htm#notinline"><B>NOTINLINE</B></A> declaration is shadowed by the rebinding of <P>
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<A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> within the nested <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> definition.<P>
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<P>
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<P>
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<B>Current Practice:<P>
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</B><P>
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Chestnut's Lisp-to-C translator conforms to this proposal.<P>
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<P>
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It appears that PCL puts all the declarations at the head of the<P>
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<A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> body at the head of the resulting lambda-expression, where<P>
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they can be shadowed by the <A REL=DEFINITION HREF="../Body/s_flet_.htm#flet"><B>FLET</B></A>.<P>
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<P>
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Lucid 4.0 appears to scope "bound" declarations in accordance with<P>
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this proposal, but not "free" declarations.<P>
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<P>
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<B>Cost to Implementors:<P>
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</B><P>
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Probably small. Note, however, that it is necessary for <A REL=DEFINITION HREF="../Body/m_defmet.htm#defmethod"><B>DEFMETHOD</B></A><P>
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and <A REL=DEFINITION HREF="../Body/t_generi.htm#generic-function"><B>GENERIC-FUNCTION</B></A> to (internally) use something like PARSE-DECLARATIONS<P>
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to compute their macro expansions, in order to sort out which declarations <P>
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apply to which binding form. Presumably many implementations have <P>
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something like that anyway, but the other cases where it's needed (<A REL=DEFINITION HREF="../Body/s_let_l.htm#letST"><B>LET*</B></A>, <P>
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(<A REL=DEFINITION HREF="../Body/a_lambda.htm#lambda"><B>LAMBDA</B></A> ...), <A REL=DEFINITION HREF="../Body/s_flet_.htm#labels"><B>LABELS</B></A>, GENERIC-LABELS) are all special forms and not<P>
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macros.<P>
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<P>
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<B>Cost to Users:<P>
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</B><P>
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Probably small.<P>
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<P>
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<B>Cost of non-adoption:<P>
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</B><P>
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Continuing vagueness in the language specification.<P>
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<P>
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<B>Performance impact:<P>
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</B><P>
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Probably small.<P>
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<P>
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<B>Benefits:<P>
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</B><P>
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The cost of non-adoption is avoided.<P>
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<P>
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<B>Esthetics:<P>
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</B><P>
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See the "rationale".<P>
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<P>
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<B>Discussion:<P>
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</B><P>
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The specification of <A REL=DEFINITION HREF="../Body/m_defmet.htm#defmethod"><B>DEFMETHOD</B></A> and the other method-defining forms<P>
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doesn't really state explicitly that <A REL=DEFINITION HREF="../Body/f_call_n.htm#call-next-method"><B>CALL-NEXT-METHOD</B></A> and <A REL=DEFINITION HREF="../Body/f_next_m.htm#next-method-p"><B>NEXT-METHOD-P</B></A><P>
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are required to be locally rebound within <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> definitions that<P>
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reference them. (Document 88-002R says they have "lexical scope and <P>
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indefinite extent".) However, it's necessary to make this point<P>
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explicit so that the behavior of test case (3) is well-defined.<P>
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<P>
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It is assumed to be unambiguous that "bound" declarations that apply <P>
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to the <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A>'s <A REL=DEFINITION HREF="../Body/a_lambda.htm#lambda"><B>lambda</B></A> variables can appear at the head of the <A REL=DEFINITION HREF="../Body/t_method.htm#method"><B>method</B></A> <P>
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body, and that the scope of the declarations is the same as the scope <P>
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of the variable bindings, although 88-002R doesn't say that explicitly<P>
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either.<P>
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</PRE>
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