输出缓冲？ 为什么不？

Question

I found few articles on the Internet that are suggesting use of ob_ functions, all of these emphase benefits, and there are no downsides of using functions mentioned.

My question is what are the downsides of using ob_ functions, or setting ini_set('output_buffering', '1'); ?

Answer 1

The cons of using output buffering entirely depend on the context of your usage.

One of the biggest cons of output buffering is your runtime error messages or warnings may get suppressed, and you may sometimes end up with erroneous data.

Consider this example:

<?php
function render_template() {
    ob_start();
    // Do some processing
    fetch_template_and_render();
    do_render();
    // end capture
    $output = ob_get_clean();
    return $output;
}

memchace::set( $some_key, render_template() );
?>

If either of fetch_template_and_render or do_render throw run time errors, they will get dumped into your output, and eventually in this example will end up in the database or cache.

Here are 2 snippets that demonstrate what I mean which you can try for yourself

#1

<?php 
    echo 1/0; 
?>

outputs

Warning: Division by zero on line 1

#2

<?php 
    ob_start();
    echo 1/0; 
    $var = ob_get_clean();
?>

outputs nothing.

To avoid such cases, you will need to be diligent about error checking and take precautions.

When used diligently, ob_* functions are very powerful and super useful.