What is [cmdletbinding()] and how does it work?

Question

According to get-help about_Functions_CmdletBindingAttribute

The CmdletBinding attribute is an attribute of functions that makes them operate like co

Answer 1

Regarding the syntax question, the format closely matches how you apply a .NET attribute class to a member using named parameters in C#.

Compare the (simplified) grammar for attributes from section B.2.4 of The PowerShell Language Specification with that from section C.2.13 of the C# Language Specification:

B.2.4 Attributes   (PowerShell)

attribute:
  [ attribute-name ( attribute-arguments ) ]

attribute-arguments:
  attribute-argument
  attribute-argument , attribute-arguments

attribute-argument:
  simple-name = expression

---

C.2.13 Attributes   (C#)

attribute:
  [ attribute-name ( named-argument-list ) ]

named-argument-list:
  named-argument
  named-argument-list , named-argument

named-argument:
  identifier = attribute-argument-expression

---

I agree it might have been nice from a sense of conceptual brevity to e.g. re-use hashtable initialization syntax for attribute initialization. However, I can imagine supporting all the options from hashtables (like [A(P=v)] and [A('P'=v)] and $n = 'P'; [A($n=v)] and such, or some particular subset of them) just to use ; as the separator character would have been more trouble than it was worth.

On the other hand, if you want to use advanced functions, then maybe it makes sense to learn an advanced syntax :)