如何从Smarty模板构造新对象？

Question

What I want to do is this:

{myfunc myattribute=new MyClass('arg1', 'arg2')}

But it gives me an error when I try, saying that the function MyClass isn't defined.

The work-around I've been using is to create a top level function like this:

function MyClass($arg1, $arg2) { return new MyClass($arg1, $arg2); }

Then in the template doing:

{myfunc myattribute=MyClass('arg1', 'arg2')}

But is there anyway to avoid creating a new top level function for every class that I want contrastable from Smarty?

I guess I could also create a function that just takes the name of a class to let me construct any class, but that's kind of an ugly solution.

Edit: To everyone telling my violating best practices, perhaps this will make you feel better:

The object I'm constructing is a widget to render some html. The actual code looks like:

{render_widget widget=new MyWidget() id="myid" name="myname"}

Also, I'm unfortunately currently stuck on PHP 5.2, so I cannot use closures. I can use the latest version of Smarty3, though I'm currently using a version of Smarty 3.0.

Answer 1

From http://www.smarty.net/best_practices

1. Do not embed PHP
2. Keep PHP constructs separate
3. Keep business logic separate

In your case you mix presentation logic with business logic - and it is bad.

However, you can write your custom Smarty plugin (wrapper) for custom objects creation - and (I think) that it is more appropriate "Smarty-way" solution.

See http://www.smarty.net/docsv2/en/plugins.tpl and http://www.smarty.net/docsv2/en/plugins.functions.tpl

For example.

Definition:

function smarty_function_custom_class($params, &$smarty)
{
    $class = $params['class'];       
    $smarty->assign($params['var'], new $class());  
}    

Usage:

{custom_class var='myObject' class='MyClass'}

---

Update

So, if you have such construction:

{render_widget widget=new MyWidget() id="myid" name="myname"}

You can change your render_widget in this way:

function smarty_function_render_widget($params, &$smarty)
{
    $class = $params['widget'];       

    $id = $params['id'];
    $name = $params['name'];

    $widget = new $class($id, $name);

    /**
     *  if you need object in your template, assign it to same variable:
     */
    $smarty->assign($params['widget'], $widget);
    // rest of your code    
}    

And after that you can use it in this way:

{render_widget widget="MyWidget" id="myid" name="myname"}

Answer 2

How about using closures ?

{myfunc myattribute=function() { return new MyClass('arg1', 'arg2'); }}

It's not the prettiest thing ever, but it should get the job done. (As a side note, you may want to consider switching to the PHP Templating language sometime in the future)

Answer 3

Unless I'm seriously mis-reading the question you are going about it the wrong way. Smarty should only hold html and the smarty variables (with very few exceptions). You'll want to write your class in PHP and instantiate an object there and pass that to smarty. Here's an example:

Php:

class Class_name
{
    private $int;

    public function funtion_name()
    {
        $this->int = 1;
        return $this->int;
    }
}

//instantiate the object  

$obj = new Class_name();

$smarty->('smarty_variable_name', $obj);

Smarty:

$smarty_variable_name->funtion_name()}

This should output 1.

Also bear with me, I wrote this on my phone :(