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https://issues.apache.org/jira/browse/DRILL-5052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15734277#comment-15734277
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ASF GitHub Bot commented on DRILL-5052:
---------------------------------------
Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/660#discussion_r91642325
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/DirectExpression.java
---
@@ -20,6 +20,12 @@
import com.sun.codemodel.JExpressionImpl;
import com.sun.codemodel.JFormatter;
+/**
+ * Encapsulates a Java expression, defined as anything that is
+ * valid in the following code:<br>
+ * <code>(<i>expr</i>)</code>
+ */
+
public class DirectExpression extends JExpressionImpl{
static final org.slf4j.Logger logger =
org.slf4j.LoggerFactory.getLogger(DirectExpression.class);
--- End diff --
Legacy code, but fixed.
> Option to debug generated Java code using an IDE
> ------------------------------------------------
>
> Key: DRILL-5052
> URL: https://issues.apache.org/jira/browse/DRILL-5052
> Project: Apache Drill
> Issue Type: Improvement
> Components: Execution - Codegen
> Affects Versions: 1.8.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Priority: Minor
>
> Drill makes extensive use of Java code generation to implement its operators.
> Drill uses sophisticated techniques to blend generated code with pre-compiled
> template code. An unfortunate side-effect of this behavior is that it is very
> difficult to visualize and debug the generated code.
> As it turns out, Drill's code-merge facility is, in essence, a do-it-yourself
> version of subclassing. The Drill "template" is the parent class, the
> generated code is the subclass. But, rather than using plain-old subclassing,
> Drill combines the code from the two classes into a single "artificial"
> packet of byte codes for which no source exists.
> Modify the code generation path to optionally allow "plain-old Java"
> compilation: the generated code is a subclass of the template. Compile the
> generated code as a plain-old Java class with no byte-code fix-up. Write the
> code to a known location that the IDE can search when looking for source
> files.
> With this change, developers can turn on the above feature, set a breakpoint
> in a template, then step directly into the generated Java code called from
> the template.
> This feature should be an option, enabled by developers when needed. The
> existing byte-code technique should be used for production code generation.
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