When Do Brackets Apply With Commands?

The answer is pretty much as in the link you posted. Broadly speaking, if you are using Call or if you are using the result of a function, then you use brackets; otherwise you do not.

Parens are used when a sub or function takes arguments (like a worksheet function).

IE:
When I do:

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I can call it with:

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But when I do:

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then I must call it and pass it a string:

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You also then have thing like byref and byval, etc.

In what way do you find intellisense misleading? It basically gives you the possible methods, properties, arguments and in some cases objects/collections that can be used as you write your code. The only time I find it a problem is when it doesnt give me anything when I know there should be.

Originally Posted by ranman256

Functions ALWAYS return a value so the params must be in parens. val = MyFunction(a,b,c)

Only if you use it.

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is also valid

What do you mean by commands, if not Subroutines and functions?

Originally Posted by Dal123

I wasn't able to ascertain much from my linked article.

Thats because the article you linked is specifically in context of calls to subs and functions. If you mean how you use parens in a command the answer depends on what the command is composed of.

Some are obvious, like using a VBA function. A VBA function like "Left()" always uses parens (as far as I know).

However something like msgbox can be confusing to new programmers.

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are both valid as is. To be honest I am not sure of the rules specifically for these as I typically just write the code and that syntax is second nature for me now.

You only use the := if you are using a named parameter- so

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When you invoke a Sub with Call, you must use parens around the arguments:

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When you assign the result of a function to a variable, you must use parens around the arguments:

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If you want to pass arguments ByVal (by value, a copy of the variable) or ByRef (by reference, a pointer to the variable), according to the procedure's signature, you don't include parens:

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If you want to pass arguments ByVal, irrespective of the procedure’s signature (which won't work for a procedure expecting an array (because arrays are always passed by reference) or an object), you enclose the argument in parens, or an extra set of parens. In the examples below, arg1 is passed by value, and arg2 according to the procedure’s signature:

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That’s because when you add parens around an argument that doesn't require them, the argument is evaluated, and the result of the evaluation is passed to the procedure. It means the argument is passed by value regardless of how the procedure requested it.

That also explains why you can't use parens around two or more arguments when they are not required; the evaluation of (arg1) may be meaningful, but the evaluation of (arg1, arg2) is not. That's why this generates an error:

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That also explains why if you call a procedure expecting a range with parens where none are required, you get a type mismatch error; because the evaluation of a range is a Variant, or Variant/Array.

You can't pass a Variant ByRef as a static type (Long, String, ...). You can pass a statically-typed variable ByRef as a Variant, and the called procedure can modify its value with data of the appropriate (or coercible) type.

So: Parens means completely different things according to context. VBA might have used some other bookends (curly braces, square brackets, whatever) to indicate enclosing a list of arguments versus a call for evaluation, but it didn't.

Since objects are always passed ByRef, you can never put unnecessary parens around an object variable. Chip Pearson (http://www.cpearson.com/excel/byrefbyval.aspx) explains the meaning of ByRef and ByVal for an object variable:

The ByRef and ByVal modifiers indicate how the reference is passed to the called procedure. When you pass an object type variable to a procedure, the reference or address to the object is passed -- you never really pass the object itself. When you pass an object ByRef, the reference is passed by reference and the called procedure can change the object to which that reference refers to. When an object is passed ByVal, a copy of the reference (address) of the object is passed.

Originally Posted by Zer0Cool

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are both valid as is.

If you use the latter, you will note that the IDE actually amends it to

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with a space after msgbox. In this context the brackets are evaluating the expression, so it is exactly the same as

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However, if you tried to pass more than one parameter like that you would get an error

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since it makes no sense to try and evaluate ("test", vbokonly). If you are not storing the result of the msgbox function, you should use

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or

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though the latter looks decidedly odd to my eyes.

Originally Posted by Dal123

I mean the actual commands e.g. Range, Err.Number etc...

Those are objects/properties, rather than commands.

Originally Posted by Dal123

xlnitwit - take for example the parameters itself; we're adding parameters; you can't add := in both areas of the parameter. The intellisence appears suggesting an opening (bracket). Yet it doesn't take a (.

I’m afraid I don’t follow. Can you clarify what you mean with an example?

Intellisense isn’t contextual in that way. It doesn’t examine your code to see if you are using Call or returning a value, it just gives the basic syntax. Bear in mind the IDE is over 20 years old.