Future/bison
1
0
Fork 0
mirror of https://git.savannah.gnu.org/git/bison.git synced 2026-03-09 12:23:04 +00:00
Code Issues Packages Projects Releases Wiki Activity

doc: motivate named references.

Browse Source 
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.
This commit is contained in:
Joel E. Denny
2011-05-29 20:06:22 -04:00
parent 908c8647de
commit 7d31f09289
2 changed files with 19 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
doc/bison.texinfo
View File

@@ -4018,10 +4018,16 @@ statement when it is followed by a semicolon.
@section Using Named References
@cindex named references
While every semantic value can be accessed with positional references
@code{$@var{n}} and @code{$$}, it's often much more convenient to refer to
them by name. First of all, original symbol names may be used as named
references. For example:
As described in the preceding sections, the traditional way to refer to any
semantic value or location is a @dfn{positional reference}, which takes the
form @code{$@var{n}}, @code{$$}, @code{@@@var{n}}, and @code{@@$}. However,
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
@group
@@ -4031,8 +4037,7 @@ invocation: op '(' args ')'
@end example
@noindent
The positional @code{$$}, @code{@@$}, @code{$n}, and @code{@@n} can be
mixed with @code{$name} and @code{@@name} arbitrarily. For example:
Positional and named references can be mixed arbitrarily. For example:
@example
@group