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doc: motivate named references.

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Suggested by Hans Aberg at
<http://lists.gnu.org/archive/html/bug-bison/2011-05/msg00008.html>.
* doc/bison.texinfo (Named References): Explain briefly how
they're better than the traditional positional references.
(cherry picked from commit 7d31f09289)
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Joel E. Denny
2011-05-29 20:06:22 -04:00
parent 378e917c55
commit a40e77ebf6
2 changed files with 19 additions and 6 deletions
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@@ -1,3 +1,11 @@
2011-05-29 Joel E. Denny <joeldenny@joeldenny.org>
doc: motivate named references.
Suggested by Hans Aberg at
<http://lists.gnu.org/archive/html/bug-bison/2011-05/msg00008.html>.
* doc/bison.texinfo (Named References): Explain briefly how
they're better than the traditional positional references.
2011-05-29 Joel E. Denny <joeldenny@joeldenny.org> 2011-05-29 Joel E. Denny <joeldenny@joeldenny.org>
doc: discuss named references after locations. doc: discuss named references after locations.

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doc/bison.texinfo
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@@ -4092,10 +4092,16 @@ statement when it is followed by a semicolon.
@section Using Named References @section Using Named References
@cindex named references @cindex named references
While every semantic value can be accessed with positional references As described in the preceding sections, the traditional way to refer to any
@code{$@var{n}} and @code{$$}, it's often much more convenient to refer to semantic value or location is a @dfn{positional reference}, which takes the
them by name. First of all, original symbol names may be used as named form @code{$@var{n}}, @code{$$}, @code{@@@var{n}}, and @code{@@$}. However,
references. For example: such a reference is not very descriptive. Moreover, if you later decide to
insert or remove symbols in the right-hand side of a grammar rule, the need
to renumber such references can be tedious and error-prone.
To avoid these issues, you can also refer to a semantic value or location
using a @dfn{named reference}. First of all, original symbol names may be
used as named references. For example:
@example @example
@group @group
@@ -4105,8 +4111,7 @@ invocation: op '(' args ')'
@end example @end example
@noindent @noindent
The positional @code{$$}, @code{@@$}, @code{$n}, and @code{@@n} can be Positional and named references can be mixed arbitrarily. For example:
mixed with @code{$name} and @code{@@name} arbitrarily. For example:
@example @example
@group @group