{"id":17834,"date":"2008-11-19T07:56:48","date_gmt":"2008-11-19T15:56:48","guid":{"rendered":"http:\/\/devblogs.microsoft.com\/powershell\/?p=17834"},"modified":"2019-06-07T07:58:10","modified_gmt":"2019-06-07T15:58:10","slug":"step-up-your-foreach-game","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/powershell\/step-up-your-foreach-game\/","title":{"rendered":"Step up your FOREACH Game"},"content":{"rendered":"

Last night Bruce Payette and I were interviewed on the PowerScripting Podcast<\/a> with Hal Rottenberg and Jonathan Walz.  It was a blast!  There were a ton of people connected and were firehosing questions & comments in the Chat window.  There were lots of comments\/discussions about Twitter.  I confessed to having never used twitter.  <\/p>\n

This morning I got an email from Jeffery Hicks<\/a> recommended a site called TweetGrid which lets you "monitor the tweet stream" without a Twitter account.  (If I get an account, do I become a Twit?)  He sent me a link to a page with search panels for PowerShell and CTP3<\/a>.<\/p>\n

I’m not ready to recommend it yet BUT the very first item on the bullet was from depping with a link to a blog post by  Hugo Peeters about script that adds RDM size info to a VI client using PowerShell<\/a>.  I love looking at other peoples scripts – it gives me a view into how they think about the world and helps me understand what patterns are in use and gives me ideas about how to evolve the language and engine.<\/p>\n

Hugo wrote a nice script – it is very easy to read and maintain.  One thing caught my eye and I left him a note about it.  He wrote:<\/p>\n

$VMs = Get-VM
ForEach ($VM in $VMs)<\/font><\/p>\n

This is perfectly fine code – it is the traditional way foreach loops are used.  But foreach loops in PowerShell are much more than that.  I’ve found that wherever I had code like that, I’m now converting it to the following form:<\/p>\n

Foreach ($VM in Get-VM)<\/font><\/p>\n

 <\/p>\n

In PowerShell, the COLLECTION part of the statement can be ANYTHING EXPRESSION OR STATEMENT<\/strong> THAT GENERATES A COLLECTION.  So you can use statements in your foreach.  I don’t have VMWARE so I can give you good VM examples but here are some examples of what I mean<\/p>\n

foreach ($p in Get-Process *ss)
{ $p.Name}
# A cmdlet is a statement which generates a collection.  Don’t worry if it
# only generates 1 value – PowerShell casts it to a collection<\/font><\/p>\n

<\/font><\/p>\n

foreach ($p in Get-Process |where {$_.handles -ge 500})
{ $p.Name}
# A pipeline is a statement as well<\/font><\/p>\n

<\/font><\/p>\n

foreach ($p in Get-Process |where {$_.handles -ge 500} | sort handles)
{ $p.Name}
# There is no restrictions on what you do in  your statement<\/font><\/p>\n

 <\/p>\n

If  you want to do something which is multiple statements, you can put them inside a $() and they are considered a single statement.
foreach ($p in $($max=700; gps |where {$_.handles -le $max})) {$p.Name}<\/font><\/p>\n

 <\/p>\n

Here is why I like this usage of foreach:<\/p>\n

    \n
  1. It is more readable\/maintainable.<\/li>\n
  2. It is smaller.  IF the code is readable, smaller code is generally better.  There are fewer things to keep track of and fewer things that can go wrong.<\/li>\n
  3. I don’t have to think up a good variable name.<\/li>\n
  4. I get a charge of the fact that you can do this in PowerShell (not a good reason but it’s honest. \ud83d\ude42 ).<\/li>\n<\/ol>\n

    Thanks for the nice script Hugo!<\/p>\n

    Thanks for the recommendation Jeffrey!<\/p>\n

    Thanks for a great podcast Hal and  Jonathan!<\/p>\n

    Cheers!<\/p>\n

    Jeffrey Snover [MSFT]
    Windows Management Partner Architect
    Visit the Windows PowerShell Team blog at:        http:\/\/blogs.msdn.com\/PowerShell<\/a>
    Visit the Windows PowerShell ScriptCenter at:      http:\/\/www.microsoft.com\/technet\/scriptcenter\/hubs\/msh.mspx<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

    Last night Bruce Payette and I were interviewed on the PowerScripting Podcast with Hal Rottenberg and Jonathan Walz.  It was a blast!  There were a ton of people connected and were firehosing questions & comments in the Chat window.  There were lots of comments\/discussions about Twitter.  I confessed to having never used twitter.  This morning […]<\/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":[192,203,247],"class_list":["post-17834","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-powershell","tag-hal-rottenberg","tag-interview","tag-powerscriptingpodcast"],"acf":[],"blog_post_summary":"

    Last night Bruce Payette and I were interviewed on the PowerScripting Podcast with Hal Rottenberg and Jonathan Walz.  It was a blast!  There were a ton of people connected and were firehosing questions & comments in the Chat window.  There were lots of comments\/discussions about Twitter.  I confessed to having never used twitter.  This morning […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/posts\/17834","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=17834"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/posts\/17834\/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=17834"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/categories?post=17834"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/powershell\/wp-json\/wp\/v2\/tags?post=17834"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}