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https://issues.apache.org/jira/browse/DRILL-5052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15732481#comment-15732481
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ASF GitHub Bot commented on DRILL-5052:
---------------------------------------

Github user arina-ielchiieva commented on a diff in the pull request:

    https://github.com/apache/drill/pull/660#discussion_r91278330
  
    --- Diff: 
exec/java-exec/src/main/java/org/apache/drill/exec/expr/DebugStringBuilder.java 
---
    @@ -0,0 +1,57 @@
    +/**
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you under the Apache License, Version 2.0 (the
    + * "License"); you may not use this file except in compliance
    + * with the License.  You may obtain a copy of the License at
    + *
    + * http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +package org.apache.drill.exec.expr;
    +
    +import java.io.PrintWriter;
    +import java.io.StringWriter;
    +
    +import com.sun.codemodel.JFormatter;
    +
    +/**
    + * Utility class to build a debug string for an object
    + * in a standard format.
    + */
    +
    +public class DebugStringBuilder {
    +
    +  private StringWriter strWriter;
    +  public PrintWriter writer;
    +  public JFormatter fmt;
    +
    --- End diff --
    
    1. Make variables private, and use getter when access is needed.
    2.  All variables can be made final.


> 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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