René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"AutomationNull Behaviour","articleBody":"See the comments in #9794 for the full extent of the existing discussion, starting with https://github.com/PowerShell/PowerShell/pull/9794#issuecomment-504796781\r\n\r\nAutomationNull.Value is sometimes detectable and distinguishable from $null in certain cases, for example:\r\n\r\n```powershell\r\nusing namespace System.Management.Automation.Internal\r\n\r\n$null -is [psobject] # false\r\n[AutomationNull]::Value -is [psobject] # true\r\n\r\n@($null).Count # 1\r\n@([AutomationNull]::Value).Count # 0\r\n```\r\n\r\n@SeeminglyScience mentioned a possible way we could have it be handled more closely like `[dbnull]` and `[nullstring]` are being handled as of #9794, without losing its current function in the pipeline internals, in https://github.com/PowerShell/PowerShell/pull/9794#issuecomment-505107426:\r\n\r\n\u003e Ideally if this were to be fixed it would just be removed from assignment, e.g. `$obj = [AutomationNull]::Value` would populate `$obj` with true `null`. The `-is` operator is one of the few things that never \"lie\" on occasion and I think it would be a detriment to change that.\r\n\u003e \r\n\u003e You can also make `[AutomationNull]::Value -is [AutomationNull]` work by:\r\n\u003e \r\n\u003e 1. Removing the `static` keyword from the class decl\r\n\u003e 2. Make it inherit `PSObject`\r\n\u003e 3. Change the singleton instance to `new AutomationNull()`\r\n\u003e \r\n\u003e That would allow `$autoNull -is [psobject]` to still work while enabling `$autoNull -is [AutomationNull]`. Though I think there are a few places in the compiler where it uses a pattern like `if (expr.ExpressionType == typeof(PSObject) \u0026\u0026 expr.Value == AutomationNull.Value)` so that might need to change.\r\n\r\n/cc @daxian-dbw @mklement0 \r\n\r\nI'm personally in favor of Patrick's solution, as it enables the very clear and concise `$item -is [AutomationNull]` with few downsides (the biggest downside being potential implementation complications, but in my opinion these are probably worth tackling). Interested to hear any further discussion on this! 💖 \r\n","author":{"url":"https://github.com/vexx32","@type":"Person","name":"vexx32"},"datePublished":"2019-06-24T18:00:30.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":44},"url":"https://github.com/9997/PowerShell/issues/9997"}