php函数调用直接作为html表单动作

Question

I have found that following HTML form code

<form action="<?php foo(bar)?>" method="post" enctype="multipart/form-data">
<label for="file">Filename:</label>
<input type="file" name="file" id="file"><br>
<input type="submit" name="submit" value="submit">
</form>

works fine when foo(bar) is a function available in the current scope.

I am very new to php and html and couldn't find any documentation of this functionality online. Are there any downsides of using <?php foo(bar)?> instead of calling a script file foo.php?

Answer 1

The PHP function will not be called as a HTML form action.

Actually the PHP function will be executed before the server send the form to your browser, so the form's action will be the value printed by the foo function if it did.

Just open the web page's sources received from your server, you shouldn't see anymore PHP code.