How to write a PowerShell advanced function that can work with both piped in objects and objects get from parameter value?

I'm writing a function Chunk-Object that can chunk an array of objects into sub arrays. For example, if I pass it an array @(1, 2, 3, 4, 5) and specify 2 elements per chunk, then it will return 3 arrays @(1, 2), @(3, 4) and @(5). Also the user can provide an optional scriptblock parameter if they want to process each elements before chunk them into sub arrays. Now my code is:

function Chunk-Object()
{
    [CmdletBinding()]
    Param(
        [Parameter(Mandatory = $true,
                   ValueFromPipeline = $true,
                   ValueFromPipelineByPropertyName = $true)] [object[]] $InputObject,
        [Parameter()] [scriptblock] $Process,
        [Parameter()] [int] $ElementsPerChunk
    )

    Begin {
        $cache = @();
        $index = 0;
    }

    Process {
        foreach($o in $InputObject) {
            $current_element = $o;
            if($Process) {
                $current_element = & $Process $current_element;
            }
            if($cache.Length -eq $ElementsPerChunk) {
                ,$cache;
                $cache = @($current_element);
                $index = 1;
            }
            else {
                $cache += $current_element;
                $index++;
            }
        }
    }

    End {
        if($cache) {
            ,$cache;
        }
    }
}


(Chunk-Object -InputObject (echo 1 2 3 4 5 6 7) -Process {$_ + 100} -ElementsPerChunk 3)
Write-Host "------------------------------------------------"
(echo 1 2 3 4 5 6 7 | Chunk-Object -Process {$_ + 100} -ElementsPerChunk 3)

The result is:

PS C:\Users\a> C:\Untitled5.ps1
100
100
100
100
100
100
100
------------------------------------------------
101
102
103
104
105
106
107

PS C:\Users\a> 

As you can see, it works with piped in objects, but does not work with values get from parameter. How to modify the code to make it work in both cases?