SourceMonitor for code metrics

http://www.campwoodsw.com/sourcemonitor.html

Following information can be retrieved in your source code:

• No. of files
• No. of lines
• No. of statements
• % of comments
• % of docs
• Classes
• Max complexity
• Max depth
• Avg. depth
• Avg complexity

If you are using a source control mechanism such as Perforce, then you can get the changes for each time period or revision. This is significantly fast also.

ANTLR important language syntaxes

* Rules begins with lower case

* Token types begins with upper case letter

* Lexer rules are given in upper case.

* x | y | z - match any alternative: x or y or z

* x? - x is optional

* x* - x can present zero or more times

* x+ - x can present one or more times

* Lexer rules are always tokens and should be given in upper case. Methods related to lexer rules are prefixed with 'm'.

Reference: The defenitive antlr reference - building domain specific languages

ANTLR FAQ

Does ANTLR knows about a specific language?
No. It recognizes the language using the provided grammar*.
ANTLR can generate a recognizer which will get a particular sentence or phrase as an input and apply the grammatical structure defined in grammar files for those input symbols.

These recognizers can be implemented using different language targets such as C# or Java.

What do you mean by grammar?
Using the grammar, we can tell ANTR how a particular language looks like, so that ANTLR can identify that. Grammar describes a syntax of a language.
Grammar will consist of set of language rules*. Grammar notation used is BNF*.

What is a rule?
A rule represents a phrase or sentence of the language.
Each rule may consist of one of more alternatives sub rules. Rules are invoked in a recursive manner.

Example for BNF notation?
Postal address ::= Name Route City Country
Name ::= First name Middle name? Last name
Route ::= Route name part*

What is a token file?
Token file can be considered as vocabulary for the grammar of specific language.

What is a target language?
Target language is a computer language which ANTLR can generate the recognizer from.

What are actions?
Actions are code blocks written in target language. Actions can refer tokens, rules or character reference using element labels. (x = T where x - label name, T - token)

How to fix "TypeInitializationException"?

This exception is thrown as a wrapper around the exception thrown by the class initializer.
Best thing is to check the inner exception details. (View details)

I got the following exception:
The type initializer for 'Antlr.StringTemplate.StringTemplate' threw an exception

Due to one assembly missing:

{"Could not load file or assembly 'antlr.runtime, Version=2.7.7.3, Culture=neutral, PublicKeyToken=d7701e059243744f' or one of its dependencies. The system cannot find the file specified.":"antlr.runtime, Version=2.7.7.3, Culture=neutral, PublicKeyToken=d7701e059243744f"}

I could fix this after I add antlr.runtime dll as a reference to the project.

Nested IF conditions vs Single line IF with AND operation

In C#, compiler will generate the same MSIL code for following code chunks.

Single line IF

if ( A && B ){
  // Do something;
}

Nested IF

if ( A ){
  if ( B ) {
  // Do something;
  }
}

How to fix TypeLoadException was unhandled Error?

Problem: I got the following runtime error while debugging my application.
TypeLoadException was unhandled

"Evaluate" is an interface method defined in a different project (Assembly A) and implemented in another project. (Assembly B).

Then I saw following warning message in the Error list:
Warning: Found conflicts between different versions of the same dependent assembly.

The given assembly name (Assembly C) for the above warmning is referenced by both Assembly A and Assembly B. It is a third party dll. Also, Assembly A is referenced by Assembly B.

Once I double clicked on the warning, it prompted me saying "One or more dependent assemblies have version conflicts. Do you want to fix these conflicts by adding binding redirect records in the app.config file?

Then, once I accepted that, the code chunk given below was automatically added to my App.config file.

Consequently, that has fixed the issue!

But I suspected that there can be some unused dlls as the above App.config entry is redirecting all assembly binding references for versions 0.0.0.0 to 3.1.3.42154 (the latest) to version 3.1.3.42154 dll. This should happen as you can't load multiple versions of the same assembly in the same app domain. So, without binding redirect, an attempt to load a different version of an already loaded assembly will fail.

Since the above code chunk sounds like a workaround to overcome the issue, I revisited the code to find the actual reason for the exception.

There, I could find that different versions of the same dll is used in two dependent projects.

So, when I refer the third party dll (Assembly C) from the same folder, same version, and remove the code chunk in the App.config, I did not get the "TypeLoadException" issue.

After doing some research on this I found that this may occur if you have an interface in one assembly and it's implementation in another, and the implementation assembly was build against a different version of the interface.

Also, this issue can occur if you load assembly dynamically using LoadFrom(string) method. I used LoadFrom method to invoke Assembly B.

Also, the project dependency given above is called as "diamond shaped" dependency which may cause this issue.

However, the error message is little bit mis-leading, but we can get some clue out of that. Exception can occur even the method is not executed during the runtime.

How to survive as a Software Engineer? It's not all about CODING!

Being a software engineer for few years and also being involved in some other fields such as quality assurance and database administration, made me to think twice on "What are the essential qualities you need to develop to survive as a software engineer?".

These may be some of the SPECIFIC qualities you need in order to ENJOY your work, (in the sense) you can still keep on working as a software engineer and gain some income without having them.
Without boasting further about it, I will get in to the topic.

1.  Being Curious

2. Love Problems (This is hilarious though!)

3. Have faith that problems will not last forever, might as well call this "Optimism"

4. See problems and challenges as means of improving - as opposed to get "Suicidal feelings"

5. Celebrate "fixing a bug"

6. Hate 8 - 5

This is it up to this time. I'll keep on adding when ever I found some more. Add anything if missing. I will elaborate on each of the above later.

Using ANTLR with Visual Studio 2008 (C# Target)

ANTLR can be used with different language targets such as C# and Java. This is how to use ANTLR with C# in VisualStudio IDE.

1. Install Java Runtime Environment (JRE).
2. Verify the above using "java -version" command.
3. Set the Java CLASSPATH variable to point the ANTLR package version you want to use. Ex: antlr-3.1.3.jar
4. Build the ANTLR project to verify that there are no issues using following command:
5. java -cp "path to ANTLR package" org.antlr.Tool "grammer file name"
6. Ex: java -cp "C:\antlr\antlr-3.1.3.jar" org.antlr.Tool tsqllexer.g

Some important options:

If you get "java.lang.OutofMemoryError: Java heap space" issue, use the following command to modify the JVM heap size.
Xmx750M

If you get "Multiple token rules can match input such as X, Tokens X.Y was disabled for that input" issue, use the following command to set NFA conversion timeout for each decision for a suitable value.
-Xconversiontimeout 10000

1. Create new C# project.
2. Add these dlls as references: antlr.runtime.dll, Antlr3.Runtime.dll, Antlr3.Utility, StringTemplate.dll
3. Build the C# project.

How to fix "Exception in thread "main" java.lang.NoClassDefFoundError:org/antlr/Too"

The following error is an initial error for ANTLR developers, when they try to build their application for the first time using command prompt:

What you need to do?

You need to set the Java Classpath for ANTLR application as given below in cmd:
set CLASSPATH = D:\antlr\antlr-3.1.3.jar

Check if it is set correctly using the following command:
echo %CLASSPATH%

Above command should display the given path.

Then verify it using the following command:
java org.antlr.Tool -version

The result should be something like this based on your ANTLR version:
ANTLR Parser Generator Version 3.1.3 Mar.18 2009 10:09:25

Why you need to do that?

The Classpath is a parameter set either command line or through envronment variable that tells JVM (Java Virtual Machine) where to look for user defined classes and packages when running Java programs. Without this, JVM does not know where to fine code base related to org.antlr.Tool.

Multi-dimensional databases vs Relational databases

Just back from the SQL Server user group meeting and the first topic was about implementing multidimensional databases using OLAP.

Below video has a good introduction about this interesting concept!