René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Select-Object -First X skips End{ } blocks of previous cmdlets","articleBody":"Using the `-First $n` parameter for `Select-Object` *completely skips* the `end {}` blocks of **all** cmdlets preceding it in the pipeline.\r\n\r\nThis can be quite hazardous, e.g., for a cmdlet that access a resource that needs to have that handle properly disposed of (like a file) may not release that handle correctly.\r\n\r\nThere is no `finally {}` block available to PS, and the method in which `Select-Object` terminates the pipeline appears to happen in such a manner that *no script-based function can account for*; that is, even *with* a `try...finally` construct in the cmdlets' `process {}` blocks it will not kick off in the event that `Select-Object` is used to prematurely end the pipeline.\r\n\r\nInstead, a method should be exposed for `Select-Object` (and potentially other cmdlets?) to *safely* terminate the pipeline by ceasing all `process` steps and kicking off the chain of `end {}` steps in the pipeline.\r\n\r\nSteps to reproduce\r\n------------------\r\n(shamelessly pinched from @TimCurwick's [fantastic example](https://gist.github.com/TimCurwick/c1794b1c2f978fc5fd9c86d19a683636) he posted in the PS Slack)\r\n```powershell\r\nfunction test {\r\n    [cmdletbinding()]\r\n    param(\r\n        [Parameter(ValueFromPipeline)]\r\n        $X \r\n    )\r\n    begin {\r\n        Write-Host \"Begin test\"\r\n    }\r\n    process {\r\n        Write-Host \"Process test\"\r\n        $X\r\n    }\r\n    end {\r\n        Write-Host \"End test\"\r\n    }\r\n}\r\n    \r\n1, 2, 3 | test | test | select -first 2\r\n```\r\n\r\nExpected behavior\r\n-----------------\r\n\r\n```none\r\nBegin Test\r\nBegin Test\r\nProcess Test\r\nProcess Test\r\n1\r\nProcess Test\r\nProcess Test\r\n2\r\nEnd Test\r\nEnd Test\r\n```\r\n\r\nActual behavior\r\n---------------\r\n\r\n```none\r\nBegin test\r\nBegin test\r\nProcess test\r\nProcess test\r\n1\r\nProcess test\r\nProcess test\r\n2\r\n```\r\n\r\nEnvironment data\r\n----------------\r\n\r\n\u003c!-- provide the output of $PSVersionTable --\u003e\r\n\r\n```powershell\r\n\u003e $PSVersionTable\r\n\r\nName                           Value\r\n----                           -----\r\nPSVersion                      6.1.0\r\nPSEdition                      Core\r\nGitCommitId                    6.1.0\r\nOS                             Microsoft Windows 10.0.17763\r\nPlatform                       Win32NT\r\nPSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}\r\nPSRemotingProtocolVersion      2.3\r\nSerializationVersion           1.1.0.1\r\nWSManStackVersion              3.0\r\n```\r\n","author":{"url":"https://github.com/vexx32","@type":"Person","name":"vexx32"},"datePublished":"2018-10-03T01:36:08.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":10},"url":"https://github.com/7930/PowerShell/issues/7930"}