10.7 Other Embperl Variables row and col
10.7 Other Embperl Variables ”$ row and $ colEmbperl 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 |
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