Deron Eriksson created SYSTEMML-611:
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Summary: Enhance display of parsing errors for user
Key: SYSTEMML-611
URL: https://issues.apache.org/jira/browse/SYSTEMML-611
Project: SystemML
Issue Type: Task
Components: Parser
Reporter: Deron Eriksson
Assignee: Deron Eriksson
Currently, if parsing errors occur, the actual messages are not displayed to
standard output or standard error except via log4j. As a result, if a user does
not have log4j configured, they do not see any of the actual parsing error
messages, which makes it extremely difficult to fix DML/PyDML.
As an example, executing the following code via DMLScript:
{code}
foo();
{code}
generates the following result to the console if log4j is not configured:
{code}
Exception in thread "main" org.apache.sysml.api.DMLException:
org.apache.sysml.parser.ParseException: One or more errors found during parsing
(could not construct AST for file: example.dml). Cannot proceed ahead.
at org.apache.sysml.api.DMLScript.executeScript(DMLScript.java:350)
at org.apache.sysml.api.DMLScript.main(DMLScript.java:197)
Caused by: org.apache.sysml.parser.ParseException: One or more errors found
during parsing (could not construct AST for file: example.dml). Cannot proceed
ahead.
at
org.apache.sysml.parser.dml.DMLParserWrapper.parse(DMLParserWrapper.java:98)
at org.apache.sysml.api.DMLScript.execute(DMLScript.java:588)
at org.apache.sysml.api.DMLScript.executeScript(DMLScript.java:338)
... 1 more
{code}
There are a few issues to address here.
1) A stacktrace such as the one above does not help an end user to write/fix
DML/PyDML. In fact, it detracts from the import information (the parse error
message) that the user needs.
2) The actual parsing errors are needed by the end user (not the stacktrace),
and these should be displayed to standard output/standard error (ie, the
console) if SystemML is being invoked via DMLScript.
3) The parsing error information should be available at higher levels of the
call stack (ie, in DMLScript and MLContext, for example). Allowing this
information to be available at these higher levels has benefits, for example to
display the parse error information in a notebook via MLContext.
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