Powershell: Returning ScriptBlocks and Closures
Powershell lets you return scriptblocks (aka anonymous functions) from functions, for example: function generateAdder ($n) { { param ($x) $n+$x } } PS C:\> $add4 = generateAdder 4 PS C:\> & $add4 7 7 If you've used languages with closures you'd have expected to get back a function that adds 4 to a passed in value. You'd expect that because $n=4 was in lexical scope when we created the scriptblock to be returned. Recall powershell is dynamically scoped so we don't need to bind ($n) to a lexcial location, instead we can pick up $n from our current environment: PS C:\> $n = "Hello" PS C:\> & $add4 7 Hello7 What if you want to instantiate a closure with powershell instead? Luckily someone thought of that and you can do: function generateAdder2 ($n) { { param ($x) $n+$x }.GetNewClosure() } PS C:\> $add4 = generateAdder2 4 PS C:\> & $add4 7 11 Leave a comment if you use th