如何从文件中读取变量（其中一些包含PHP代码），并解析PHP代码？

I have to PHP files, one contains variables, some of which contains PHP code:

/* variables.php */

<?php
    $oneVariable = "Hello";
    $anotherVariable = "<<<EOF
<h1>Headline</h1>
<p>Text</p>
<?php echo "I whish this would work!" ?>
EOF;

And another one that I access:

/* output.php */

include("variables.php");
echo "$oneVariable World!";
echo "$anotherVariable";

When accessing output.php through a browser I will get:

Hello World!
Headline
Text
<?php echo "I whish this would work!" ?>

But I'd like the php code in the heredoc to be parsed so that I only see "I whish this would work!".

How can I accomplish that?

EDIT: Don't want to ruin the question by editing out my original example, so here's another one:

I'm want to be able to have one template file:

/* index.php */
<?php
include("article.php");
?>

<title><?php echo "$title" ?></title>
<?php echo "$articleContents" ?>

And a bunch of files containing data for articles, for example this one:

/* article.php */
<?php
$title = "About grapes";
$articleContents = <<<EOF
<h1>The wrath</h1>
<p>Even though the title of this article is <?php echo "$title" ?>,
     what I'm personally really into is raisins!</p>
EOF;

When I request index.php I want to get the "formatted" article.

<?php echo "I whish this would work!" ?>

Replace with:

I whish this would work!

This is just a syntax error, you cannot have php tags embeded in a string declaration. Presuming you do need some kind of logic to be used in the creation of the $anotherVariable string, you just need to construct those parts before the declaration:

$oneVariable = "Hello";
$message = "I wish this would work!";

$anotherVariable = "<<<EOF
    <h1>Headline</h1>
    <p>Text</p>
    $message
EOF;

Another option, if $anotherVariable is to contain a more complex template, would be to use output buffering:

$oneVariable = "Hello";
//start output buffering
ob_start(); 
//now exit php mode, and define the template, inlcluding html and php interspersed
?>

<h1>Headline</h1>
<p>Text</p>
<?php echo "I whish this would work!" ?>

<p>Text</p>
<ul>
<?php foreach([1,2,3] as $el):?>
    <li>item number <?php echo $el;?> </li>
<?php endforeach;?>
</ul>
<?php
//save output to variable
$anotherVariable = ob_get_clean();

There's no clean simple way to achieve what you want. The simplest thing is to keep the actual template in a separate file and include it:

/* variables.php */

<?php

$oneVariable = 'Hello';
$template = 'foo.php';

/* output.php */

include 'variables.php';

echo "$oneVariable World!";
include $template;

Try this out:

function render($path, $data = ''){
    foreach ($data as $key => &$value) {
        //parse the contents of each variable
        ob_start();
        eval('?>' . $value);
        $value = ob_get_clean();
    }
    //bundle variables with template
    ob_start();
    extract($data);
    require $path;
    $content = ob_get_clean();
    return $content;
}

$title = "About grapes";
$articleContents = <<<EOF
<h1>The wrath</h1>
<p>Even though the title of this article is <?php echo "$title" ?>,
     what I'm personally really into is raisins!</p>
EOF;

$data = compact('title', 'articleContents');

echo render('t.txt', $data);

And the template (t.txt):

<h1><?php echo $title; ?></h1>
<hr>
<article>
    <p><?php echo $articleContents; ?></p>
</article>

An output buffer may be preferable to a HEREDOC.

<?php
$var_one = 'I wish you were here.';
ob_start();
?>
     <h1>Running over the same old ground</h1>
     <p>Something <?php echo some_func('blah'); ?> wicked this way comes.</p>
<?php
$var_two = ob_get_clean();

You could place the html in another file if needed:

ob_start();
include '/path/to/file.php';
$output = ob_get_clean();