How to Display output from snippet without using echo

The documentation on snippets in modx: http://rtfm.modx.com/display/revolution20/Snippets

Near the top of the doc it says: Note how we returned the code rather than echo'ed the content out. Never use echo in a Snippet - a开发者_开发问答lways return the output.

This doesn't display anything:

return $product_attribute $product_info[0][$column_name];

This does display:

echo $product_attribute $product_info[0][$column_name];

If I can't echo the content how do I get it to print in the html page?

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It basically means that you can echo the returned value rather than echo the value in the function itself. In OOP programming, echoing (or printing) to the screen is strictly monitored.

For example I have this function

function testExample($var) {
    return $var*2;
}

So when I need to echo it, I just need to

echo testExample(5);

Instead of this (bad practice)

function testExample($var) {
    echo $var*2;
}

The reason is that when you print value in the function, you can only use that function for printing the value, which isn't reusable at all. But by returning it, you can now use it for printing, or assigning to another variable or re-calculating on it.

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From what I can understand from the note, there is a convention not to use echo inside a function, but rather return the value and perhaps echo it afterwards.

Other printing posibilities would be:

print $your_variable;

or die($your_variable);

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return is used to return values from a function/method ect The snippet functionality of modx is actually just a function/class wrapper.