10.7 Other Embperl Variables row and col

10.7 Other Embperl Variables ”$ `row` and $ `col`

Embperl can generate one- or two-dimensional tables dynamically with the use of $row and/or $col . If either $row or $col (or $cnt ) is used within a <table> , Embperl repeats the text between <table> and </table> as long as the expression that includes $row / $col does not evaluate to undef .

For instance, if a program has this code:

 [- @nums = (1..5); -]  <table>    <tr><td>[+ $nums[$row] +]</td></tr>  </table>

this means start the table and then use $row to loop through @nums , one element at a time. And because it is $row , each element is treated as a row, so it repeats <tr><td> ... </td></tr> . Therefore, this is the result of this code:

 <table>    <tr><td>1</td></tr>    <tr><td>2</td></tr>    <tr><td>3</td></tr>    <tr><td>4</td></tr>    <tr><td>5</td></tr>  </table>

Changing the code to this:

 [- @nums = (1..5); -]  <table>    <tr><td>[+ $nums[$col] +]</td></tr>  </table>

loops through @nums , and because we use $col , each element is treated as a column, so it repeats <td> ... </td> . Therefore, this is the result of this code:

 <table>    <tr><td>1</td><td>2</td><td>3</td><td>4</td><td>5</td></tr>  </table>

Cool HTML table magic!

As an example, we display the environment variables in a table. First, we show how the table might be built without the magic and then how more magic makes life better. This code can be found in /var/www/html/embperl/rowcol.html :

 <html>  <head>  <title>Using $row and $col</title>  </head>  <body bgcolor="#ffffff">  <h1>Using a <tt>foreach</tt></h1>  <table border="1">  [# loop through the sorted keys of %ENV, #]  [# printing the keys and their values    #]  [$ foreach $key (sort keys %ENV) $]    <tr><th> [+ $key +] </th><td> [+ $ENV{$key} +] </td></tr>  [$ endforeach $]  </table>  <h1>Using the Magical <tt>$row</tt> and <tt>$col</tt></h1>  [# grab the sorted keys of %ENV, put them in @k      #]  [# then, define one row in the table, and $row will  #]  [# magically take on the values of the indices of @k #]  [- @k = sort keys %ENV -]  <table border="1">    <tr><th> [+ $k[$row] +] </th><td> [+ $ENV{$k[$row]} +] </td></tr>  </table>  </body>  </html>

Try this program by going to one of these URLs: http://localhost/embperl/rowcol.html or www.opensourcewebbook.com/embperl/rowcol.html. You should see something that resembles Figure 10.6.

Figure 10.6. Using `$row` and `$col`

graphics/10fig06.jpg

10.7 Other Embperl Variables ”$ row and $ col

Figure 10.6. Using $row and $col

10.7 Other Embperl Variables ”$ `row` and $ `col`

Figure 10.6. Using `$row` and `$col`