iText 7 - how to ensure proper cleanup of resources on exceptions

Question

For iText7, sample code (from https://kb.itextpdf.com/home/it7kb/examples/itext-7-jump-start-tutorial-chapter-6 )

using System;
using System.IO;
using iText.Kernel.Pdf;
using iText.Kernel.Utils;

namespace Tutorial.Chapter06 {
    public class C06E04_88th_Oscar_Combine {
        public const String SRC1 = "../../../resources/pdf/88th_reminder_list.pdf";

        public const String SRC2 = "../../../resources/pdf/88th_noms_announcement.pdf";

        public const String DEST = "../../../results/chapter06/88th_oscar_combined_documents.pdf";

        public static void Main(String[] args) {
            FileInfo file = new FileInfo(DEST);
            file.Directory.Create();
            new C06E04_88th_Oscar_Combine().CreatePdf(DEST);
        }

        public virtual void CreatePdf(String dest) {
            //Initialize PDF document with output intent
            PdfDocument pdf = new PdfDocument(new PdfWriter(dest));
            PdfMerger merger = new PdfMerger(pdf);
            //Add pages from the first document
            PdfDocument firstSourcePdf = new PdfDocument(new PdfReader(SRC1));
            merger.Merge(firstSourcePdf, 1, firstSourcePdf.GetNumberOfPages());
            //Add pages from the second pdf document
            PdfDocument secondSourcePdf = new PdfDocument(new PdfReader(SRC2));
            merger.Merge(secondSourcePdf, 1, secondSourcePdf.GetNumberOfPages());
            firstSourcePdf.Close();
            secondSourcePdf.Close();
            pdf.Close();
        }
    }
}

What I'm not sure about, is whether resources like open files will be cleaned up properly, if an exception occurs inside a method like CreatePdf. Is there a way to rewrite CreatePdf, perhaps using "using" blocks etc., that could ensure more robust clean up if/when things go wrong ? Or is the code, as written, robust enough for real life use ?

Answer 1

You can use using on objects that implements IDisposable to ensure they are disposed when you leave the function (and in case of exception). You dont need to call Close on them. And add a catch to delete the file.

public virtual void CreatePdf(String dest) 
{
  try
  {
      using var writer = new PdfWriter(dest);
      ...
  } 
  catch (Exception)
  {
    File.Delete(dest);
    throw;
  }
}