{"id":9763,"date":"2011-08-31T07:00:00","date_gmt":"2011-08-31T07:00:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/oldnewthing\/2011\/08\/31\/modernizing-our-simple-program-that-retrieves-information-about-the-items-in-the-recycle-bin\/"},"modified":"2011-08-31T07:00:00","modified_gmt":"2011-08-31T07:00:00","slug":"modernizing-our-simple-program-that-retrieves-information-about-the-items-in-the-recycle-bin","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20110831-00\/?p=9763","title":{"rendered":"Modernizing our simple program that retrieves information about the items in the Recycle Bin"},"content":{"rendered":"

\nLast time,\n\nwe wrote a simple program to print various properties of the items\nin the Recycle Bin<\/a>,\nand we did so in the classical style,\nusing item ID lists and IShell­Folder<\/code>s.\nOne thing you may have noticed is that a lot of functions take\nthe combination of an IShell­Folder<\/code> and a\nPCUITEMID_CHILD<\/code>.\nIn the shell namespace, operations on items usually happen\nby means of the pair (folder, child),\nand one of the common mistakes made by beginners is\nfailing to keep track of the pairing and passing child pidls\nto the wrong parent folder.\n<\/p>\n

\nEven if you’re not a beginner and are good at keeping track of\nwhich child pidls correspond to which parent folders,\nit’s still extra work you have to do,\nand it means that a lot of functions take two parameters in order to\ndescribe one thing.\n<\/p>\n

\nEnter IShell­Item<\/code>.\n<\/p>\n

\nThe IShell­Item<\/code> encapsulates the pair (folder, child).\nThis solves two problems:\n<\/p>\n

    \n
  1. You only have to pass one thing around (the IShell­Item<\/code>)\n instead of two (the IShell­Folder<\/code> and the\n PCUITEMID_CHILD<\/code>).<\/p>\n
  2. By keeping track of the two items as a single unit,\n it reduces the risk that you’ll accidentally use a child pidl\n with the wrong parent folder.\n<\/ol>\n

    \nAnother complexity of the classic shell interface is that there\nare a bunch of ways of obtaining COM objects from a shell folder:\n<\/p>\n