Coding standards - inclusion

[Eric Bauman]

Hi there,

 From http://pear.php.net/manual/en/standards.including.php: "Anywhere
you are unconditionally including a class file, use require_once.
Anywhere you are conditionally including a class file (for example,
factory methods), use include_once."

Out of curiosity, why is this the case? What benefits does it offer?

Best regards,
Eric

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[Christian Weiske]

Hello Eric,

>  From http://pear.php.net/manual/en/standards.including.php:
> "Anywhere you are unconditionally including a class file, use
> require_once. Anywhere you are conditionally including a class file
> (for example, factory methods), use include_once."
>
> Out of curiosity, why is this the case? What benefits does it offer?

A failed require leads to a fatal error which is not catchable by code.
In you library, you should include a file and throw an exception if
that failed - this is programmatically verifiable.


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Christian Weiske

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[Eric Bauman]

On 13/10/2009 7:54 PM, Christian Weiske wrote:

> Hello Eric,
>
>>    From http://pear.php.net/manual/en/standards.including.php:
>> "Anywhere you are unconditionally including a class file, use
>> require_once. Anywhere you are conditionally including a class file
>> (for example, factory methods), use include_once."
>>
>> Out of curiosity, why is this the case? What benefits does it offer?
>
> A failed require leads to a fatal error which is not catchable by code.
> In you library, you should include a file and throw an exception if
> that failed - this is programmatically verifiable.
>
>

Thank-you for the response, and good point.

Is there some recommended way of checking success? I thought of this:

if (@include 'test.php')
        echo 'yes';
else
        throw new Exception('no');

Some say the error control operator is quite slow; is there some
advantage to the above vs:

if (file_exists('test.php'))
        require 'test.php';
else
        throw new Exception('no');


Cheers,
Eric

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[Christian Weiske]

Hello Eric,

> >>    From http://pear.php.net/manual/en/standards.including.php:
> >> "Anywhere you are unconditionally including a class file, use
> >> require_once. Anywhere you are conditionally including a class file
> >> (for example, factory methods), use include_once."
> >>
> >> Out of curiosity, why is this the case? What benefits does it
> >> offer?
> >
> > A failed require leads to a fatal error which is not catchable by
> > code. In you library, you should include a file and throw an
> > exception if that failed - this is programmatically verifiable.
>
> Thank-you for the response, and good point.
>
> Is there some recommended way of checking success? I thought of this:
>
> if (@include 'test.php')
> echo 'yes';
> else
> throw new Exception('no');

I would not do that - especially during development, a syntax error in
test.php would be silenced and you'd stare at a white page without
knowing anything.

> Some say the error control operator is quite slow; is there some
> advantage to the above vs:
>
> if (file_exists('test.php'))
> require 'test.php';
> else
> throw new Exception('no');
That one does not work with files in your include path.

I'd include the file without any file_exist checks. If you really need
to know if your file is includable, use fopen with the
search-include-path option on (3rd parameter).

After inclusion, you can do a class_exists check to see if the class
you expected is available.


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Mit freundlichen Grüßen
Christian Weiske

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