Switch/Flag Parameters in PowerShell

I wanted to create a function with a ‘-force’ option.  First, I tried to add a [boolean] parameter, but that doesn’t work because it needs a value with the argument; I want it to be invoked with just the presence of the switch/flag.  Here’s how I finally did it:

function Update-Something {
    param(
        [switch] $force)

    if ($force) { 
        #do something here
    }
}


# use like:
$> Update-Something -force

Rounding In PowerShell

Another simple one (from John D. Cook):

$> [int] 1.1
1

$> [int] 1.5
2

$> [int] 1.8
2

PowerShell: Parse Date from String

Incredibly simple (checkout this PowerShell Cookbook):

$> (get-date 2000/01/01)

Saturday, January 01, 2000 12:00:00 AM

PowerShell Format-List (fl)

Staying with the late to the party theme on my PowerShell adventure, today I discovered Format-List (fl alias).  You can pipe results into it and get more detailed output.

Without Format-List:

PS> [Array]

IsPublic IsSerial Name         BaseType
-------- -------- ----         --------
True     True     Array        System.Object

With Format-List:

PS> [Array] | fl

Module                     : CommonLanguageRuntimeLibrary
Assembly                   : mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b7
                             7a5c561934e089
TypeHandle                 : System.RuntimeTypeHandle
DeclaringMethod            : 
BaseType                   : System.Object
UnderlyingSystemType       : System.Array
FullName                   : System.Array
AssemblyQualifiedName      : System.Array, mscorlib, Version=4.0.0.0, Culture=neutral, Pub
                             licKeyToken=b77a5c561934e089
Namespace                  : System
GUID                       : 200fb91c-815d-39e0-9e07-0e1bdb2ed47b
IsEnum                     : False
GenericParameterAttributes : 
IsSecurityCritical         : False
IsSecuritySafeCritical     : False
IsSecurityTransparent      : True

PowerShell RegEx

Trying to learn PowerShell by using it to create a NuGet build scripts. In order to parse some code files, I needed to filter a list of strings using a regular expression and capture a match group from the first string matched:

$line = 
    $assembly_info | 
    where {$_ -match 'AssemblyDescription\("(?<1>[^"]*)"\)'} | 
    select -first 1

$matches[1]

Looks almost like a functional language.  Better late to the party than never…