hadoop@ip-10-245-54-191:~/top50/new$ cat a.pig
DEFINE mymacro(blah, zoo) RETURNS foo {
x = JOIN $blah BY id, $zoo BY id;
        y = JOIN x BY $blah::id, $zoo BY id;
 $foo = foreach y generate x::$blah::id;
};
raw = load 'a.txt' as (id:chararray);
mymacro(raw, raw);
#############################################

with the above code, I had to refer to fields within a JOIN result by the
table name, which is passed in as a MACRO param. but it seems that pig
can't recognize this syntax:

hadoop@ip-10-245-54-191:~/top50/new$ pig -x local a.pig
2012-11-07 23:40:53,524 [main] INFO  org.apache.pig.Main - Logging error
messages to: /home/hadoop/top50/new/pig_1352331653520.log
2012-11-07 23:40:53,636 [main] INFO  org.apache.pig.impl.util.Utils -
Default bootup file /home/hadoop/.pigbootup not found
2012-11-07 23:40:53,739 [main] INFO
 org.apache.pig.backend.hadoop.executionengine.HExecutionEngine -
Connecting to hadoop file system at: file:///
<file a.pig, line 4, column 30>  Unexpected character '$'
2012-11-07 23:40:54,399 [main] ERROR org.apache.pig.tools.grunt.Grunt -
ERROR 1200: <file a.pig, line 4, column 30>  Unexpected character '$'
Details at logfile: /home/hadoop/top50/new/pig_1352331653520.log
how can I work around this?

thanks
Yang