Software Carpentry

Today finished reading the software carpentry. It introduces the basic principles of software engineering to research scientists and engineers. In doing so in a short and effective manner, it claims to introduce 10% of the software engineering that can meet 90% of the needs. This material becomes open licensed since 2005.

PHPUnit, Hudson CI, Doxygen and Silverlilght

PHPUnit is used for writing unit tests in PHP. This is a first tutorial.

Hudson CI is a continuous integration server system. Can be used for automated unit testing.

Doxygen is a documentation system for many programming languages.

Silverlight is Microsoft's RIA solution coming with MPF. See here for tutorial.

MS SQL schema

Obtain metadata of objects of a database can add lots of flexibility. This can be obtained in the following ways:

1) INFORMATION_SCHEMA
e.g.:
select table_name as Name FROM INFORMATION_SCHEMA.Tables where TABLE_TYPE ='VIEW'

2) sysobjects
e.g.:
SELECT name FROM sysobjects WHERE xtype = 'U' -- Tables
SELECT name FROM sysobjects WHERE xtype = 'V' -- Views
SELECT name FROM sysobjects WHERE xtype = 'P' -- Stored Procedures

A Subversion Cheat Sheet

SVN can use a GUI interface such as TortoiseSVN, or a command line version such as slik SVN.

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Setup ssh key for svn so no need to enter password each time: HOWTO: set up ssh keys

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A short usage note for Subversion.

Often used svn commands are:

Create a Repository

UNIX: svnadmin create /path/to/repository
Windows: svnadmin create d:/path_to_repository

Checking Out a Project - svn checkout

UNIX: svn checkout file:///repository_name/project/trunk project
Windows: svn checkout file:///d:/repository_name/project/trunk project
Network: svn checkout http://host_name/svn_dir/repository_name/project/trunk project

Getting a List of Projects - svn list

UNIX: svn list --verbose file:///repository_name/project
Network: svn list --verbose http://host_name/svn_dir/repository_name/project

Reviewing Changes - svn status

UNIX: svn status

Adding New Files and Directories - svn add

UNIX: svn add file_or_dir_name

Deleting Files and Directories - svn delete

UNIX: svn delete file_or_dir_name
Network: svn delete -m "Deleting project dir" http://localhost/svn_dir/repository/project_dir

Committing Changes - svn commit

Network: svn commit -m "Saving recent changes" http://localhost/svn_dir/repository/project_dir

Updating Your Local Files - svn update

Network: svn update

Get revision number - svn info

svn info | grep Rev

Check log for the 10 most recent entries:

svn log --limit 10
or
svn log -l 10

MSSQL extended property

MSSQL extended property is used to store metadata information on database objects (tables, views, columns, indexes etc.).

- Extended Property is NOT case sensitive.
- MSDN: add, drop, update, list extended properties:
  http://msdn.microsoft.com/en-us/library/ms180047.aspx

- list all extended properties:
  SELECT * FROM sys.extended_properties;
- list all extended properties for columns in all tables:
  SELECT major_id, minor_id, t.name AS [Table Name], c.name AS [Column Name], value AS [Extended Property]
  FROM sys.extended_properties AS ep
  INNER JOIN sys.tables AS t ON ep.major_id = t.object_id 
  INNER JOIN sys.columns AS c ON ep.major_id = c.object_id AND ep.minor_id = c.column_id
  WHERE class = 1;
- Show all the E.P. of a specific columns in a specific table:
  SELECT objtype, objname, name, value
  FROM fn_listextendedproperty (NULL, 'schema', 'dbo', 'table', 'T1', 'column', 'id');
  
Add/drop/update/list the Extended Property of a column:
  
- Show an E.P. of a columns in a table:
  SELECT objtype, objname, name, value
  FROM fn_listextendedproperty ('[E.P. name]', 'schema', 'dbo', 'table', 'T1', 'column', 'id');

- Add an E.P. of a column in a table (the IF part is optional check):

  IF NOT Exists (SELECT * FROM fn_listextendedproperty(
    'Summary', 'schema', 'dbo', 'table', 'T1', 'column', 'id'
  ))
  EXEC sp_addextendedproperty 
    @name = 'caption' 
    ,@value = 'Employee ID' 
    ,@level0type = 'schema', @level0name = dbo
    ,@level1type = 'table', @level1name = 'T1'
    ,@level2type = 'column', @level2name = id;
  GO

- Drop an E.P. of a column in a table (the IF part is optional check):

  IF Exists (SELECT * FROM fn_listextendedproperty(
    'Summary', 'schema', 'dbo', 'table', 'T1', 'column', 'id'
  ))
  EXEC sp_dropextendedproperty 
    @name = 'caption' 
    ,@level0type = 'schema', @level0name = dbo
    ,@level1type = 'table', @level1name = 'T1'
    ,@level2type = 'column', @level2name = id;
  GO

- Update an E.P. of a column in a table:
  EXEC sp_updateextendedproperty 
    @name = N'Caption'
    ,@value = 'Employee ID must be unique.'
    ,@level0type = N'Schema', @level0name = dbo
    ,@level1type = N'Table',  @level1name = T1
    ,@level2type = N'Column', @level2name = id;
  GO

Add/drop/update/list the Extended Property of a table:

- The above shows how to add/drop/update/list the E.P. of a column.
  To do the same thing for a table, just ignore the last 2 items for
  level2type/level2name. For the IF part, use NULL for the last two items. E.g.:
  IF Exists (SELECT * FROM fn_listextendedproperty(
    'Summary', 'schema', 'dbo', 'table', 'T1', NULL, NULL
  ))
  Examples are given below.

- Drop an extended property of a table:  
  IF Exists (SELECT * FROM fn_listextendedproperty(
    'Summary', 'schema', 'dbo', 'table', 'T1', null, null
  ))
  EXEC sp_dropextendedproperty 
    @name = 'Summary' 
    ,@level0type = 'schema' ,@level0name = dbo
    ,@level1type = 'table' ,@level1name = 'T1';
  GO
  
- Add an extended property to a table:  
  IF NOT Exists (SELECT * FROM fn_listextendedproperty(
    'Summary', 'schema', 'dbo', 'table', 'T1', null, null
  ))
  EXEC sp_addextendedproperty 
    @name = 'Summary' 
    ,@value = 'T1 table''s summary' 
    ,@level0type = 'schema' ,@level0name = dbo
    ,@level1type = 'table' ,@level1name = 'T1';
  GO  

Add/drop/update/list the Extended Property of a view or view's column:

- Same as table, except that use "view" instead of "table" as level1type.
  
Note:

- Since single quote "'" is used as delimiter, it should escaped
  by "''" if it is used in the value.
- Note that string quoted by "'" is allowed to contain new line character.
  So if a value spans multiple lines, it won't be a problem.

Perl OOP and reference

Perl can do OOP for sure. I reviewed relevant material for recent work. Use "Package" to define a class. What's interesting is the use of "bless" keyword. An object is used in the syntax of a C++ object, say you use "->" to retrieve its member variable or function.

The use of reference facilitates a lot of programming features. In Perl using a back slash "\" in front of a variable (scalar, array or hash) turns it into a reference. This can be passed to subroutines, to be used recursively etc. To cast it back and refer to the object, use $/@{}/%{} for scalar/array/hash respectively.

References:
- Object Oriented Programming in PERL

Perl - count number of occurrences

http://www.chengfu.net/2005/10/count-occurrences-perl/

The author wants to find out what's the fastest way of counting occurrences of a string in a text. e.g. '-' in “1-4-7-8-37-5-7-8-3-42″. He gives 5 ways of doing this:

1. my $size = (scalar(@{[$string =~ /-/g]}) + 1);
2. my $size = scalar(split /-/, $string);
3. my $size = (($string =~ s/-//g) + 1);
4. my $size = (($string =~ tr/-//) + 1);
5. my $size = 1; $size++ while $string =~ /-/g;

He found the speed to be 4, 3, 5, 1, 2 in the order of fastest to slowest on his machine.