Using TCPDF across multiple classes

Question

I am trying to write a function that would call multiple classes, each would add a widget to a single PDF file and then return that entire PDF file.

Here's the constructor's code:

<?php

class PdfConstructor {

    protected $logger; // I'm sure there's another way to use the logger located in the public dependencies without having to initalise it here

    public function __construct($logger){
        $this->logger = $logger;
    }

    public function studentPdf(){
        $pdf = new TCPDF(PDF_PAGE_ORIENTATION, PDF_UNIT, PDF_PAGE_FORMAT, true, 'UTF-8', false);

        // ---------------------------------------------------------
        require 'pdfwidgets/studentheader.php'; // TODO: Need to load this via autoloader
        $headerController = new StudentHeader($pdf);
        $headerInfo = $hederController->getHeader();

        // ---------------------------------------------------------

        //Close and output PDF document
        $pdf->Output('C:\xampp7\htdocs\edquire-api\logs\test.pdf', 'F');
    }
}

Then in studentheader I have this:

<?php

class StudentHeader {

    protected $pdf;

    public function __construct($pdf){
        $this->$pdf = $pdf;
    }

    public function getHeader(){
        $this->pdf->AddPage();
    }
}

I am trying to pass the $pdf object to studentheader but I'm getting the error:

Catchable fatal error: Object of class TCPDF could not be converted to string in C:\xampp7\htdocs\edquire-api\classes\pdfwidgets\studentheader.php on line 8

Why is it trying to convert it to string, and is there a better way to achieve constructing that pdf using widgets?

Answer 1

This is line 8:

 $this->$pdf = $pdf;

It should be:

 $this->pdf = $pdf;

It's saying it can't convert $pdf to a string because property names need to be a string. You're using it as a property name there.

Footnote to this: if you don't "get" an error message, it's always a good strategy to Google it. I googled "Catchable fatal error: Object of class TCPDF could not be converted to string" and the top results all point one on the right direction.