A couple months ago we asked our MVPs how they felt about reserving keywords in V2. We received some excellent but mixed feedback, so we\u2019d like to open the discussion up a bit wider.<\/p>\n
There are keywords we hope to use in a future version of PowerShell, but won\u2019t be implemented in V2. \u201cclass\u201d, \u201cusing\u201d, and \u201cnew\u201d are excellent candidates for additions to PowerShell, but we haven\u2019t decided on the exact list yet.<\/p>\n
Because V1 did not reserve these keywords, reserving them now would be a breaking change. For example, some people like to add an alias like:<\/p>\n
New-Alias<\/span> -Name<\/span> new<\/span> -Value<\/span> New-Object<\/span><\/pre>\nIf we reserved \u201cnew\u201d, scripts using this alias would be broken. Similarly, in Bruce Payette\u2019s book \u201cWindows PowerShell In Action\u201d, he describes a way to implement a keyword like \u201cclass\u201d, though he uses \u201cCustomClass\u201d instead of \u201cclass\u201d<\/p>\n
The biggest benefit of reserving in V2 is that we\u2019ll break fewer scripts.<\/p>\n
The cons to reserving in V2 include:<\/p>\n
\n- Breaking scripts needlessly. We\u2019ve tried to make V2 as backwards compatible as possible. The breaking changes that we do have implement real functionality (for example, try\/catch are new keywords, breaking scripts that used try or catch as a function.) <\/li>\n
- Some keywords can be implemented in script, at least well enough to look like a real keyword. <\/li>\n<\/ul>\n
Here\u2019s an example of how you might implement the C# using statement in a V2 PowerShell script:<\/p>\n
function<\/span> using<\/span>\n{<\/span>\n param<\/span>(<\/span>$obj<\/span>,<\/span> [scriptblock]<\/span>$sb<\/span>)<\/span>\n try<\/span> {<\/span>\n &<\/span> $sb<\/span>\n }<\/span> finally<\/span> {<\/span>\n if<\/span> (<\/span>$obj<\/span> -is<\/span> [IDisposable]<\/span>)<\/span> {<\/span>\n $obj<\/span>.<\/span>Dispose<\/span>(<\/span>)<\/span>\n }<\/span>\n }<\/span>\n}<\/span> <\/pre>\nAnd here is how you can use that function \u2013 it looks very similar to how a using keyword might look:<\/p>\n
using<\/span> (<\/span>$stream<\/span> =<\/span> new-object<\/span> System.IO.StreamReader<\/span> $PSHOME\\types.ps1xml<\/span>)<\/span> {<\/span>\n foreach<\/span> (<\/span>$_<\/span> in<\/span> 1<\/span>..<\/span>5<\/span>)<\/span> {<\/span> $stream<\/span>.<\/span>ReadLine<\/span>(<\/span>)<\/span> }<\/span>\n}<\/span><\/pre>\nFeel free to give us your feedback in the comments \u2013 are you using any common language keywords as a function name in your scripts? If you do, how bothersome would it be if you had to change your scripts?<\/p>\n
– Jason Shirk [MSFT]<\/p>\n","protected":false},"excerpt":{"rendered":"
A couple months ago we asked our MVPs how they felt about reserving keywords in V2. We received some excellent but mixed feedback, so we\u2019d like to open the discussion up a bit wider. There are keywords we hope to use in a future version of PowerShell, but won\u2019t be implemented in V2. \u201cclass\u201d, \u201cusing\u201d, […]<\/p>\n","protected":false},"author":600,"featured_media":13641,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-4361","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-powershell"],"acf":[],"blog_post_summary":"
A couple months ago we asked our MVPs how they felt about reserving keywords in V2. We received some excellent but mixed feedback, so we\u2019d like to open the discussion up a bit wider. There are keywords we hope to use in a future version of PowerShell, but won\u2019t be implemented in V2. \u201cclass\u201d, \u201cusing\u201d, […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/posts\/4361","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/users\/600"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/comments?post=4361"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/posts\/4361\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/media\/13641"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/media?parent=4361"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/categories?post=4361"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/tags?post=4361"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}