On Fri Mar 30 07:44:12 EDT 2012, [email protected] wrote:
> "fn name @{block}" doesn't cause block to run in a sub-shell, although
> it accepts the syntax.
> Is it someting should not be tried, or something shoud be fixed?
you've misunderstood the current grammar. you have defined 2 functions
name and '@' as {block}. the binding, illustrated with parens is
fn (name @) {block}
the production in the grammer is
FN words brace
but since once production for words is words -> keyword, a keyword
is a valid function name.
so if you have
fn @{echo hi, mom}
then
ladd; fn @{echo hi, mom} # space makes no difference
ladd; whatis @
fn @ {echo hi, mom}
ladd; @
ladd; '@'
hi, mom
one could argue that this is a misfeature, since you can define
a function named 'for' or 'if' or '~' or '!'. i don't currently see how
disallowing
keywords in function names would be a problem, but it would
require at least 1 new production in the grammar.
note that "fn {echo bar}" is also legal, but doesn't do anything.
i've attached a change to the grammar that addresses this oddity.
- erik
----
broken! diffy -c syn.y
/n/dump/2012/0330/sys/src/cmd/rc/syn.y:29,35 - syn.y:29,35
struct tree *tree;
};
%type<tree> line paren brace body cmdsa cmdsan assign epilog redir
- %type<tree> cmd simple first word comword keyword words wordsnl
+ %type<tree> cmd simple first word nkword comword keyword nkwords words wordsnl
%type<tree> NOT FOR IN WHILE IF TWIDDLE BANG SUBSHELL SWITCH FN BREAK
%type<tree> WORD REDIR DUP PIPE
%%
/n/dump/2012/0330/sys/src/cmd/rc/syn.y:81,88 - syn.y:81,88
| assign cmd %prec BANG {$$=mung3($1, $1->child[0], $1->child[1], $2);}
| BANG cmd {$$=mung1($1, $2);}
| SUBSHELL cmd {$$=mung1($1, $2);}
- | FN words brace {$$=tree2(FN, $2, $3);}
- | FN words {$$=tree1(FN, $2);}
+ | FN nkwords brace {$$=tree2(FN, $2, $3);}
+ | FN nkwords {$$=tree1(FN, $2);}
simple: first
| simple word {$$=tree2(ARGLIST, $1, $2);}
| simple redir {$$=tree2(ARGLIST, $1, $2);}
/n/dump/2012/0330/sys/src/cmd/rc/syn.y:91,96 - syn.y:91,98
word: keyword {lastword=1; $1->type=WORD;}
| comword
| word '^' word {$$=tree2('^', $1, $3);}
+ nkword: comword
+ | word '^' word {$$=tree2('^', $1, $3);}
comword: '$' word {$$=tree1('$', $2);}
| '$' word SUB words ')' {$$=tree2(SUB, $2, $4);}
| '"' word {$$=tree1('"', $2);}
/n/dump/2012/0330/sys/src/cmd/rc/syn.y:107,109 - syn.y:109,113
|
words: {$$=(struct tree*)0;}
| words word {$$=tree2(WORDS, $1, $2);}
+ nkwords: {$$=(struct tree*)0;}
+ | nkwords nkword {$$=tree2(WORDS, $1, $2);}
