clarification about parameter binding

[Garegin Asatryan Participant Topics: 21 Replies: 22 Points: 35Rank: Member]

both $source and $dest are System.IO.FileInfo objects. I can see through trace-command that it’s taking the value of “C:\foo.log” and converting it to string (the input type for -path). the question is how does it get the value of c:\foo.log. How does it know which of $source’s parameters to use.

 

Trace-Command ParameterBinding -Expression {Copy-Item -Path $source -Destination $dest -force} -PSHost

DEBUG: ParameterBinding Information: 0 : BIND NAMED cmd line args [Copy-Item]
DEBUG: ParameterBinding Information: 0 : BIND arg [C:\foo.log] to parameter [Path]
DEBUG: ParameterBinding Information: 0 : COERCE arg to [System.String[]]
DEBUG: ParameterBinding Information: 0 : Trying to convert argument value from System.IO.FileInfo to
System.String[]

 

 

[Rob Simmers Participant Topics: 16 Replies: 1792 Points: 3,290Rank: Community Hero]

This is a educated guess, but most likely it attempts a conversion with ToString().

PowerShell

PS C:\Users\rasim> $file = Get-Item -Path C:\Scripts\apps.xml PS C:\Users\rasim> $file.GetType() IsPublic IsSerial Name BaseType -------- -------- ---- -------- True True FileInfo System.IO.FileSystemInfo PS C:\Users\rasim> $file.ToString() C:\Scripts\apps.xml

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

PS C:\Users\rasim> $file = Get-Item -Path C:\Scripts\apps.xml     PS C:\Users\rasim> $file.GetType()     IsPublic IsSerial Name                                     BaseType -------- -------- ----                                     -------- True     True     FileInfo                                 System.IO.FileSystemInfo       PS C:\Users\rasim> $file.ToString()   C:\Scripts\apps.xml

As to what ToString() is doing, it appears to get the Fully Qualified Name, which in this case is the FullName. More information about ToString can be found here:
StackOverflow Thread: https://tinyurl.com/y4v4veum

[Garegin Asatryan Participant Topics: 21 Replies: 22 Points: 35Rank: Member]

As to what ToString() is doing, it appears to get the Fully Qualified Name, which in this case is the FullName. More information about ToString can be found here

https://docs.microsoft.com/en-us/dotnet/api/system.object.tostring?view=netcore-3.1 talks more about it.

I never did real dev so don’t know how methods are implemented, overloading, overriding etc. But I got the gist of the idea. It wasn’t binding to any specific parameter but converting the object to a string.

thanks for the help.

[kvprasoon Senior Moderator Topics: 9 Replies: 1365 Points: 5,024Rank: Community MVP]

yes exactly, its a string conversion and AFAIK, done with this internally [System.Management.Automation.LanguagePrimitives]::ConvertTo($Path,’string’)

[js Participant Topics: 32 Replies: 847 Points: 2,723Rank: Community Hero]

The words are cutoff in my browser.

I think you mean which of the $source properties. “-path” of of type string, so powershell casts or coerces $source to type string.

[js Participant Topics: 32 Replies: 847 Points: 2,723Rank: Community Hero]

I can’t edit the last post.

[kvprasoon]

js wrote:

I can’t edit the last post.

@js2010 Fixed. There was a long url text in Rob’s post making the posts non editable. I just removed it.

• This reply was modified 3 days, 11 hours ago by kvprasoon.

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