PHP Use 'eval' As a Function (Get Return Value)

Question

Background

I'm using a 4D server. 4D has a built in PHP processor, but in an odd way. I have to start an inline 4D script in my webpage, then I have to call up PHP Execute, and give it the path of a .php file.

4D Script

C_TEXT($result)
C_BOOLEAN($isOK)
$isOK:=PHP Execute("C:\\php\\myPHPFile.php";"my_function";$result)
ALERT($Result)

myPHPFile.php

<?php
    function my_function() {
        return 'Hello World';
    }
?>

Goal

I want to be able to write this in my webiste:

<?php echo 'Hello World'; ?>

And have it processed. I almost have it figured out. If I first convert it via the server code (4D can do that) to this:

C_TEXT($result)
C_BOOLEAN($isOK)
$isOK:=PHP Execute("";"echo 'Hello World'";$result)
ALERT($Result)

You are supposed to be able to run PHP native functions directly without a .php file. You'd think that would work. Turns out it doesn't.

So I tried this:

C_TEXT($result)
C_BOOLEAN($isOK)
$isOK:=PHP Execute("";"echo";$result;"Hello World") // I can send parameters
ALERT($Result)

Still doesn't work. Turns out that I need to evaluate the code using a function.

C_TEXT($result)
C_BOOLEAN($isOK)
$isOK:=PHP Execute("";"eval";$result;"return 'Hello World;'") // I can send parameters
ALERT($Result)

That SHOULD send "return 'Hello World';" to eval(). Well that STILL doesn't work, because I've found out that eval() isn't actually a function. So what I need to know, after all that background, is this:

Question

Is there a native function in PHP that would work like this:

$evaulatedCode = eval($unEvaluatedCode);

Just, out of curiosity, where is `$Result` declared/initialized? — Brandon White, Sep 24 '15 at 20:59
Yes, that is why I need a function that would work like `eval`, so that I can put it in there. — Kelderic, Sep 24 '15 at 21:03
To answer the question part `eval("\$evaulatedCode = $unEvaluatedCode");` — AbraCadaver, Sep 24 '15 at 21:06
Never heard about that. If you ask me, one of the things you don't need for web development is that proprietary 4D stuff. — hek2mgl, Sep 24 '15 at 21:06
hek, the main reason I'm asking is so that on the web pages, I can just write PHP instead of having to write in the proprietary 4D stuff. — Kelderic, Sep 24 '15 at 21:08
No `$evaluatedCode` will be assigned the return of the evaluated code and be available in global scope. I was answering the stated question, I have no knowledge of 4D. — AbraCadaver, Sep 24 '15 at 21:09
@AndyM Got your point. Believe me, I've worked >10 years in web dev but I've never heard of 4D before. I guess you are doing it on customer's request. (I pity you in that case!) Otherwise I would simply not use that 4D stuff. (Note that I've removed the 4d tag, because it relates to 4d in the sense of 4 dimensions. Check the tag description.) — hek2mgl, Sep 24 '15 at 21:53
If you want to capture the *output* of eval, then use `ob_start` etc. and `eval("?>$script — mario, Sep 24 '15 at 22:09

Barmar · Accepted Answer · 2015-09-24T22:43:45.550

2

You were pretty close, you have the semicolon in the wrong place in your return statement. Try this:

$isOK:=PHP Execute("";"eval";$result;"return 'Hello World';")

edited Sep 24 '15 at 22:43

answered Sep 24 '15 at 21:09

Barmar

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Doesn't work. `eval` was my first thought too, as I explained in the question. But `eval` isn't a function. It doesn't return a value. I think as I review this more that it isn't possible to do what I want. – Kelderic Sep 24 '15 at 21:19
Actually, now that I recheck the documentation, I think your `return` statement should have worked. The manual says: _eval() returns NULL unless return is called in the evaluated code, in which case the value passed to return is returned._ – Barmar Sep 24 '15 at 22:42
That's odd then that it doesn't work. I'm wondering if 4D just isn't treating the eval statement as an official "function". – Kelderic Sep 25 '15 at 12:13
I suppose anything is possible if it has its own PHP interpreter instead of using the real thing. Did you fix the semicolon as I showed? You had it inside the single quotes. – Barmar Sep 25 '15 at 15:33

PHP Use 'eval' As a Function (Get Return Value)

Background

Goal

Question

1 Answers1