How to create a smarty variable in prestashop 1.5

I am working on a button that switches view with onClick. I wish to store the last/default position in a variable in order to prevent switching to the default view state on each page refresh or navigation.

I read that I can do the following in a php file:

$myVar= -1;
$smarty->assign('myVar', $myVar);

and then use `$myVar` in the tpl file. But it does not work for me.
The tpl file I am working on is not part of a module and has no .php file in the prestashop root folder.

Can anyone educate me a little on smarty/php and how to create variables and use them to store button's state?

Thanks

In order to use variables in your smarty file, you need to use for example :

$this->context->smarty->assign(
array(
'myVar' => $myvar,
'otherVar' => $otherVar
)
);

Then to use it in your tpl file you simply need to use :

<div>my var = {$myVar}</div>

To use a variable in your smarty you need to write it inside {}.

Smarty is a PHP template engine for PHP, which facilitates the separation of presentation (XHTML/CSS) from the PrestaShop's core functions/controllers.

A template file (usually with a .tpl extension in PrestaShop) is always called by a PHP controller file (it can be a Front-end core controller or a module controller).

Example: `/prestashop/controllers/front/ContactController.php`

$this->context->smarty->assign(array(
'contacts' => Contact::getContacts($this->context->language->id),
'message' => html_entity_decode(Tools::getValue('message'))
));

$this->setTemplate(_PS_THEME_DIR_.'contact-form.tpl');

We can see that this file is retrieving information from the database and assigning it to Smarty.

Then, the 'contact-form.tpl' template will display it to the visitors.

The syntax is pretty similar for modules,
example:`/prestashop/modules/blocklink/blocklink.php`

public function hookLeftColumn($params)
{
$this->smarty->assign('blocklink_links', $this->getLinks());

return $this->display(__FILE__, 'blocklink.tpl');
}

Also, to store values in Smarty variables, you can use the 'assign' function in two ways:

1. `$this->context->smarty->assign('my_smarty_variable_name', $my_value);`

or if you have several variables:

2. `$this->context->smarty->assign(array('my_smarty_variable_name1' => $my_value1), ('my_smarty_variable_name2' => $my_value2));`

And then in the Smarty template:

The value of my variable is {$my_smarty_variable_name|escape:'htmlall':'UTF-8'}.

The 'escape' modifier is used to avoid XSS security issues.