There is one programing concept that always hurts my head, and that is the variable variables or dynamic variables. What dynamic let you do is access data from the value of the a variable you are viewing. (See I told you it would hurt your head)

 
$b =20;  // set the value of b
$c="b";  // set c to the name of the variable you want to view
$d=${$c}; // the variable variable  $d is now equal to 20
 

Many of you are probably asking yourself, " OK I understand that , but why do I need to do that?"
The number one place I use this, is in a web grid form. Any place you need to update/or delete data in that grid. Below is an example of what a grid of data may look like:

The issues you face in the above grid is how do I delete multiple items and change multiple elements of data in grid once it is submitted. The solution is you assign each field a row number and add that to the field name.

Example:

 
<input name="del_1" type="checkbox" />
<input name="id_1" type="hidden" value="117" />
<input name="del_2" type="checkbox" />
<input name="id_2" type="hidden" value="95" />

Note each field had its name attached with a _row number so you will see an id_1 as a field name. After this form is submitted you can use the below php code to get the values dynamically.


// Check for item delete
if ((isset($_POST['delete'])) or (isset($_POST['delete_x']))){
for ($i=0; $i<=$totrecs; $i++)
{
$tdel=$_POST['del_'.$i];
$tid=$_POST['id_'.$i];
// Another way to do this is this way
// $tempvar="id_".$i;
// $tid=$_POST[${$tempvar}];
if ($tdel=="on")
{
// Delete Item, the item ID is $tid
}
} // Loop
} // End Post Check


Template Lite And Dynamic Variables
Form Data grid is also the reason I used dynamic variables in templates. Once I have edited a data grid I need to set values in the grid, select drop downs and, check radio or check boxes. There is some extra steps you need to do to use them and it also depends on how you pass your data to template lite. The following is an example showing a more complex use of variable variables.

{foreach key=key2 value=item2 from=$jetarray }
{ assign var="dummyvar1" value="`$item2.jetski_id`_bookid"}
{ assign var="dummyvar2" value="`$item2.jetski_id`_owner"}
{ assign var="cellcolor" value="`$item2.jetski_id`_color"}
{ assign var="dummyvar3" value="`$item2.jetski_id`"}
 
 {if $item[$dummyvar1]!=""}
   {if $session.myid == $item[$dummyvar2]}
<input name="jetid_{$item2.jetski_id}_{$key}" type="hidden"
 value="{$item2.jetski_id}" />
   {/if}
{/if}
 
 {/foreach}

Note we assigned a variable $dummyvar1 with the value $item2.jetski_id and appended _bookid to that variable name. Jetski number 1 turns into 1_bookid. After that we pull the value out of the array $item[$dummyvar1] so what we are actually doing is viewing $item['1_bookid'].

While there are some other uses for dynamic variables these are how I most recently have used them. If it helps someone other than myself, cool. Otherwise this is a place I have my own personal reference library.

One of the greatest tools I have in my library set is Template Lite . Template lite is a light-weight version of another template engine known as Smarty. Once you start using template lite you will be pleasantly surprised by how powerful yet modular it is.

My whole point of this blog is to talk about modifiers. A modifier enables you to pass some php modifying code into a template lite variable.

Example:


{$mytlitevariable|ucfirst }
//This would capitalize the first letter of the variable.
What doesn't work

It is important to note that you cannot necessarily use this on all modify type php functions. Some php functions do not pass the main variable into the first option.

Using str_replace would not work as the passed variable is the third option in the command. {$mytlitevariable|str_replace:black:brown }
//is the equivalent to
str_replace($mytlitevariable,"black","brown")
//which will not work. You will have to use it via php:
{php} echo str_replace("black","brown",$mytlitevariable) {/php}

Modifiers Stacking

Modifier stacking allows you to make multiple changes to a variable by passing multiple modifiers to the template lite variable.

Example: {$myvar|ucfirst|truncate:40:"..."}

Creating your own Modifiers

Don't be afraid to create your own modifiers. When ever I run into something that I can't do I add it into template lite.
//Example: This is the source code for the indent modifier.
//Once you create the modifier and save it in the plugins folder with the name
//modifier.indent.php.
{$myvar|indent}
//Note there are 2 extra arguments you can use with it as well.

function tpl_modifier_indent($string,$chars=4,$char=" ")
{
return preg_replace('!^!m',str_repeat($char,$chars),$string);
}
This is the start of my experimentation with blogs. I am constantly forgetting how to do things with template lite and other things. I plan on adding these tips and tricks to my blog so I have one place to search for the info. Feel free to comment as I realize I don't know it all but am willing to share my experiences along the way.