Call one script from another

iangoldby

I want to conditionally load and run php code in a second file based on the outcome of a test in the first file. The second file is big and expensive to load and parse.

The manual says

Note: Prior to PHP 4.0.2, the following applies: require() will always attempt to read the target file, even if the line it's on never executes.

Unfortunately my host still uses version 4.0.1. I want to know how I can achieve something similar so that the considerable expense of loading the second script on every page is avoided, when it is only needed occasionally. (The second script just writes some site stats data to a file, so it doesn't return any values to the first script, nor does it output anything to the browser.)

Thanks.

bobthedog

The "include" function!!!

http://www.php.net/manual/en/function.include.php.

If you read the online manual I believe include is linked to from the require functions page - so remember to look there in future!

iangoldby

Thanks. Unfortunately, include() works the same way as require() - e.g.

if ($condition)
{
  include ('bigscript.inc');
}

If $condition is FALSE, versions 4.0.2+ will not read in bigscript.inc. Version 4.0.1 and earlier will read and parse it regardless (but not actually execute the code in it).

I want to avoid opening, reading, and parsing bigscript.inc if $condition is FALSE in version 4.0.1.

bobthedog

Hmmm - I am not convinced that this is happening... however, I don't have 4.0.2 or lower installed anywhere at present, and I can't be bothered to go about it....

Anyhow - follow this....

how can a file be included even if that code block is not executed. As far as I recall (many apologies if I am wrong) but include(..) is not a pre-processor directive, therefore should not actually be executed until it gets to that line. BUT, if PHP never goes to that line, then the file should never be included. Take this example:


$strFilename = 'no_file';

if (false)
{
    // Unless something very screwy is going on PHP will NEVER get here and therefore no code should get executed
    $strFilename = 'test.inc.php';
    include($strFilename);
}
else
{
    // But it will get here
}

print($strFilename);

In the above code PHP will never get to "$strFilename = 'test.inc.php';" and so, $strFilename will never be set to the correct value, and no file will be included. If it tried to, the include would fail and produce a PHP warning. Warning's only appear on the 2nd pass of the PHP (code execution - the 1st pass would be parsing the file), this therefore proves (in a convoluted way) that "include" is not a pre-processor directive, and so is only executed when that line is reached.

Anyhow - I am going a slightly long winded way about describing this - but it's the end of a long weeked so I apologise!

In summary - I cannot test this because I don't have the time or the inclanation to install an old version of PHP. However, if you are convinced it is happening, then place the include filename into a variable and call include with that variable. If this manages to include the file (as you suggest it would), then I would be totally shocked, since the pre-processor and syntactic check will not look at variable values since the code is not being executed.

In short - I don't think you have a problem....but try the above if you are convinced you do 🙂

iangoldby

Thanks again.

I've tried out your test script (or a simplified version - I don't think making the include file name a variable is necessary).

Anyway, it works as you describe on both my local machine (4.2.1) and on the server (4.0.1). However, when I change 'include' to 'require' then on version 4.2.1 it is happy whereas on version 4.0.1 it stops with an error that it cannot find the required file.

I think I agree with you then - include() only tries to read the file in if it would be executed. On the other hand require() requires the file regardless in <=4.0.1, but only if it would be executed in >=4.0.2.

Thanks for helping me to clear that up. I read the documentation as meaning the only difference between include() and require() was whether it aborts on error. Looks like it's a bit more subtle than that in earlier versions.