The WhereObject cmdlet is incredibly powerful, in that it allows you to filter your output based on arbitrary criteria. For extremely simple filters (such as filtering based only on a comparison to a single property), though, the syntax can get a little ungainly:
GetProcess | WhereObject { $_.Handles gt 1000 }
load all the syntax to the script itself:
GetProcess | CompareProperty Handles gt 1000 GetChildItem | CompareProperty PsIsContainer
With a shorter alias, this becomes even easier to type:
PS >gt;SetAlias wheres CompareProperty PS >GetChildItem | wheres Length gt 100
Example 23 implements this “simple where” functionality. Note that supplying a nonexisting operator as the $operator parameter will generate an error message.
Example 23. CompareProperty.ps1
############################################################################## ## CompareProperty.ps1 ## ## Compare the property you provide against the input supplied to the script. ## This provides the functionality of simple WhereObject comparisons without ## the syntax required for that cmdlet. ## ## Example: ## GetProcess | CompareProperty Handles gt 1000 ## dir | CompareProperty PsIsContainer ############################################################################## param($property, $operator = "eq", $matchText = "$true")
Begin { $expression = "`$_.$property $operator `"$matchText`"" } Process { if(InvokeExpression $expression) { $_ } }
