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[Maxima-commits] CVS: maxima/doc/info Operators.texi, 1.49, 1.50 Function.texi, 1.52, 1.53
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From: Robert D. <rob...@us...> - 2008-06-29 19:40:33
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Update of /cvsroot/maxima/maxima/doc/info In directory sc8-pr-cvs16.sourceforge.net:/tmp/cvs-serv26483/doc/info Modified Files: Operators.texi Function.texi Log Message: Attempt to clarify "local" declaration. Resolves [ 679435 ] local(func) should be emphasised in the documentation. Index: Operators.texi =================================================================== RCS file: /cvsroot/maxima/maxima/doc/info/Operators.texi,v retrieving revision 1.49 retrieving revision 1.50 diff -u -d -r1.49 -r1.50 --- Operators.texi 17 Feb 2008 20:33:17 -0000 1.49 +++ Operators.texi 29 Jun 2008 19:40:25 -0000 1.50 @@ -967,7 +967,9 @@ All function definitions appear in the same namespace; defining a function @code{f} within another function @code{g} -does not limit the scope of @code{f} to @code{g}. +does not automatically limit the scope of @code{f} to @code{g}. +However, @code{local(f)} makes the definition of function @code{f} +effective only within the block or other compound expression in which @code{local} appears. If some formal argument @var{x_k} is a quoted symbol, the function defined by @code{:=} does not evaluate the corresponding actual argument. @@ -1027,6 +1029,25 @@ (%o2) c + b + a @end example +@code{local} makes a local function definition. + +@c ===beg=== +@c foo (x) := 1 - x; +@c foo (100); +@c block (local (foo), foo (x) := 2 * x, foo (100)); +@c foo (100); +@c ===end=== +@example +(%i1) foo (x) := 1 - x; +(%o1) foo(x) := 1 - x +(%i2) foo (100); +(%o2) - 99 +(%i3) block (local (foo), foo (x) := 2 * x, foo (100)); +(%o3) 200 +(%i4) foo (100); +(%o4) - 99 +@end example + @opencatbox @category{Function definition} @category{Operators} @closecatbox Index: Function.texi =================================================================== RCS file: /cvsroot/maxima/maxima/doc/info/Function.texi,v retrieving revision 1.52 retrieving revision 1.53 diff -u -d -r1.52 -r1.53 --- Function.texi 9 Mar 2008 02:30:59 -0000 1.52 +++ Function.texi 29 Jun 2008 19:40:27 -0000 1.53 @@ -576,6 +576,16 @@ block is exited the saved values are restored, and the values assigned within the block are lost. +The declaration @code{local(@var{v_1}, ..., @var{v_m})} within @code{block} +saves the properties associated with the symbols @var{v_1}, ..., @var{v_m}, +removes any properties before evaluating other expressions, +and restores any saved properties on exit from the block. +Some declarations are implemented as properties of a symbol, +including @code{:=}, @code{array}, @code{dependencies}, @code{atvalue}, @code{matchdeclare}, +@code{atomgrad}, @code{constant}, @code{nonscalar}, @code{assume}, and some others. +The effect of @code{local} is to make such declarations effective only within the block; +otherwise declarations within a block are actually global declarations. + @code{block} may appear within another @code{block}. Local variables are established each time a new @code{block} is evaluated. Local variables appear to be global to any enclosed blocks. @@ -584,12 +594,6 @@ otherwise, it is the value of the variable in the global environment. This policy may coincide with the usual understanding of "dynamic scope". -If it is desired to save and restore other local properties -besides @code{value}, for example @code{array} (except for complete arrays), -@code{function}, @code{dependencies}, @code{atvalue}, @code{matchdeclare}, @code{atomgrad}, @code{constant}, and -@code{nonscalar} then the function @code{local} should be used inside of the block -with arguments being the names of the variables. - The value of the block is the value of the last statement or the value of the argument to the function @code{return} which may be used to exit explicitly from the block. The function @code{go} may be used to transfer @@ -732,7 +736,9 @@ All function definitions appear in the same namespace; defining a function @code{f} within another function @code{g} -does not limit the scope of @code{f} to @code{g}. +does not automatically limit the scope of @code{f} to @code{g}. +However, @code{local(f)} makes the definition of function @code{f} +effective only within the block or other compound expression in which @code{local} appears. If some formal argument @var{x_k} is a quoted symbol (after evaluation), the function defined by @code{define} does not evaluate the corresponding actual argument. @@ -1478,18 +1484,46 @@ @c NEEDS CLARIFICATION AND EXAMPLES @deffn {Function} local (@var{v_1}, ..., @var{v_n}) -Declares the variables @var{v_1}, ..., @var{v_n} to be local with -respect to all the properties in the statement in which this function -is used. + +Saves the properties associated with the symbols @var{v_1}, ..., @var{v_n}, +removes any properties before evaluating other expressions, +and restores any saved properties on exit +from the block or other compound expression in which @code{local} appears. + +Some declarations are implemented as properties of a symbol, +including @code{:=}, @code{array}, @code{dependencies}, @code{atvalue}, @code{matchdeclare}, +@code{atomgrad}, @code{constant}, @code{nonscalar}, @code{assume}, and some others. +The effect of @code{local} is to make such declarations effective only within the block +or other compound expression in which @code{local} appears; +otherwise such declarations are global declarations. + +@code{local} can only appear in @code{block} +or in the body of a function definition or @code{lambda} expression, +and only one occurrence is permitted in each. @code{local} quotes its arguments. @code{local} returns @code{done}. -@code{local} may only be used in @code{block}, in the body of function -definitions or @code{lambda} expressions, or in the @code{ev} function, and only one -occurrence is permitted in each. +Example: -@code{local} is independent of @code{context}. +A local function definition. + +@c ===beg=== +@c foo (x) := 1 - x; +@c foo (100); +@c block (local (foo), foo (x) := 2 * x, foo (100)); +@c foo (100); +@c ===end=== +@example +(%i1) foo (x) := 1 - x; +(%o1) foo(x) := 1 - x +(%i2) foo (100); +(%o2) - 99 +(%i3) block (local (foo), foo (x) := 2 * x, foo (100)); +(%o3) 200 +(%i4) foo (100); +(%o4) - 99 +@end example @opencatbox @category{Function definition} @category{Programming} |