X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Fflow-control.texi;h=72d7a052cd4379bb9fb475c76530b669fcef1f9b;hb=49aaf665f7ad1fed25d23b6ccb0da1c5461c4846;hp=c68923f8c052f35fe39cb3255daa2375e554a75b;hpb=440613afbc2b901f51020c36afd59255a4988aa6;p=pspp

diff --git a/doc/flow-control.texi b/doc/flow-control.texi
index c68923f8c0..72d7a052cd 100644
--- a/doc/flow-control.texi
+++ b/doc/flow-control.texi
@@ -45,6 +45,7 @@ BREAK.
 @vindex DEFINE
 @cindex macro
 
+@node Macro Overview
 @subsection Overview
 
 @display
@@ -53,20 +54,23 @@ BREAK.
 @t{!ENDDEFINE.}
 @end display
 
+@noindent
 Each @i{argument} takes the following form:
 @display
-@r{@{}@i{!arg_name} @t{=},@t{!POSITIONAL}@r{@}}
+@r{@{}@i{!arg_name}@t{=} @math{|} @t{!POSITIONAL}@r{@}}
 @r{[}@t{!DEFAULT(}@i{default}@t{)}@r{]}
 @r{[}@t{!NOEXPAND}@r{]}
-@r{@{}@t{!TOKENS(}@i{count}@t{)},@t{!CHAREND('}@i{token}@t{')},@t{!ENCLOSE('}@i{start}@t{','}@i{end}@t{')},@t{!CMDEND}@}
+@r{@{}@t{!TOKENS(}@i{count}@t{)} @math{|} @t{!CHAREND('}@i{token}@t{')} @math{|} @t{!ENCLOSE('}@i{start}@t{' @math{|} '}@i{end}@t{')} @math{|} @t{!CMDEND}@}
 @end display
 
+@noindent
 The following directives may be used within @i{body}:
 @example
 !OFFEXPAND
 !ONEXPAND
 @end example
 
+@noindent
 The following functions may be used within the body:
 @display
 @t{!BLANKS(}@i{count}@t{)}
@@ -83,6 +87,7 @@ The following functions may be used within the body:
 @t{!UPCASE(}@i{arg}@t{)}
 @end display
 
+@noindent
 The body may also include the following constructs:
 @display
 @t{!IF (}@i{condition}@t{) !THEN} @i{true-expansion} @t{!ENDIF}
@@ -98,6 +103,7 @@ The body may also include the following constructs:
 @t{!LET} @i{!var} @t{=} @i{expression}
 @end display
 
+@node Macro Introduction
 @subsection Introduction
 
 The DEFINE command creates a @dfn{macro}, which is a name for a
@@ -243,8 +249,8 @@ A @dfn{positional} argument has a required value that follows the
 macro's name.  Use the @code{!POSITIONAL} keyword to declare a
 positional argument.
 
-When a macro is called, every positional argument must be given a
-value in the same order as the defintion.
+When a macro is called, the positional argument values appear in the
+same order as their definitions, before any keyword argument values.
 
 References to a positional argument in a macro body are numbered:
 @code{!1} is the first positional argument, @code{!2} the second, and
@@ -266,10 +272,7 @@ FREQUENCIES /VARIABLES=!1.
 @item
 A @dfn{keyword} argument has a name.  In the macro call, its value is
 specified with the syntax @code{@i{name}=@i{value}}.  The names allow
-keyword argument values to take any order in the call, and even to be
-omitted.  When one is omitted, a default value is used: either the
-value specified in @code{!DEFAULT(@i{value})}, or an empty value
-otherwise.
+keyword argument values to take any order in the call.
 
 In declaration and calls, a keyword argument's name may not begin with
 @samp{!}, but references to it in the macro body do start with a
@@ -291,7 +294,13 @@ FREQUENCIES /VARIABLES=!vars.
 
 If a macro has both positional and keyword arguments, then the
 positional arguments must come first in the DEFINE command, and their
-values also come first in macro calls.
+values also come first in macro calls.  A keyword argument may be
+omitted by leaving its keyword out of the call, and a positional
+argument may be omitted by putting a command terminator where it would
+appear.  (The latter case also omits any following positional
+arguments and all keyword arguments, if there are any.)  When an
+argument is omitted, a default value is used: either the value
+specified in @code{!DEFAULT(@i{value})}, or an empty value otherwise.
 
 Each argument declaration specifies the form of its value:
 
@@ -575,6 +584,8 @@ Expands to a number token representing the number of characters in
 @deffn {Macro Function} !NULL
 Expands to an empty character sequence.
 
+@c Keep these examples in sync with the test for !NULL in
+@c tests/language/control/define.at:
 @example
 !NULL                        @expansion{} @r{empty}
 !QUOTE(!NULL)                @expansion{} ''
@@ -593,6 +604,8 @@ to the string's contents, with the quotes removed and any doubled
 quote marks reduced to singletons.  If the argument was not a quoted
 string, @code{!UNQUOTE} expands to the argument unchanged.
 
+@c Keep these examples in sync with the test for !QUOTE and !UNQUOTE in
+@c tests/language/control/define.at:
 @example
 !QUOTE(123.0)                @expansion{} '123.0'
 !QUOTE( 123 )                @expansion{} '123'
@@ -995,11 +1008,9 @@ code block is executed.  The condition is evaluated at the end of the
 loop, not at the beginning, so that the body of a loop with only a
 condition on @cmd{END LOOP} will always execute at least once.
 
-If the index clause is not
-present, then the loop is executed at most @var{max_loops} (@pxref{SET}) times
-(but possibly fewer, if a condition clause evaluates to false or if
-@cmd{BREAK} executes).
-The default value of @var{max_loops} is 40.
+If the index clause is not present, then the global @code{MXLOOPS}
+setting, which defaults to 40, limits the number of iterations
+(@pxref{SET MXLOOPS}).
 
 @cmd{BREAK} also terminates @cmd{LOOP} execution (@pxref{BREAK}).