php如何在for循环中重新声明类

Question

Im using a library called PDFmerger , naturally, it merges pdfs together. I wish to run a cron every night that builds these to have them ready for the next day. The issue is when I run the code after the first one it fails because it is attempting to redeclare the class.

The for statement...

            foreach ($pdfs_to_build as $pdf) {

                // do stuff

                $this->merge_pdfs($pdf['pdf_id']);

            }

And my pdf merging code that gets ran in the loop...

$pdf = new PDFMerger;

$pdf->addPDF(DIR_BOOKS.$book_path.'/static-pages/page-1.pdf', '1'); 
$pdf->addPDF(DIR_FINAL_PDFS.$pdf_id.'/custom-page-1.pdf','1'); 
$pdf->addPDF(DIR_BOOKS.$book_path.'/static-pages/page-2.pdf', '1'); 

$pdf->merge('file', DIR_FINAL_PDFS.$pdf_id.'/final-build-'.$pdf_id.'.pdf');

Error after the first 1 is complete and we've onto the next one...

Fatal error: Cannot redeclare class PDFMerger in /var/www/example/pdfmerger/PDFMerger.php on line 24

Im wondering is there a workaround for this?

Answer 1

The problem isn't that you're calling new PDFMerger twice, that's perfectly acceptable. The problem is that the file:

/var/www/example/pdfmerger/PDFMerger.php

Is being include'd (or otherwise executed) twice, which has on line 24:

class PDFMerger {

That is what is triggering your error, that class has already been declared. Figure out why that file is being included twice and your error will clear up.