如何将工具提示放在用户定义的函数上

Professional Excel Development by Stephen Bullen describes how to register UDFs, which allows a description to appear in the Function Arguments dialog:

Function IFERROR(ByRef ToEvaluate As Variant, ByRef Default As Variant) As Variant
If IsError(ToEvaluate) Then
IFERROR = Default
Else
IFERROR = ToEvaluate
End If
End Function


Sub RegisterUDF()
Dim s As String
s = "Provides a shortcut replacement for the common worksheet construct" & vbLf _
& "IF(ISERROR(<expression>), <default>, <expression>)"


Application.MacroOptions macro:="IFERROR", Description:=s, Category:=9
End Sub


Sub UnregisterUDF()
Application.MacroOptions Macro:="IFERROR", Description:=Empty, Category:=Empty
End Sub

From: http://www.ozgrid.com/forum/showthread.php?t=78123&page=1

To show the Function Arguments dialog, type the function name and press CtrlA. Alternatively, click the "fx" symbol in the formula bar:

Unfortunately there is no way to add Tooltips for UDF Arguments.
To extend Remou's reply you can find a fuller but more complex approach to descriptions for the Function Wizard at
http://www.jkp-ads.com/Articles/RegisterUDF00.asp

Not a tooltip solution but an adequate workaround:

Start typing the UDF =MyUDF( then press CTRL + Shift + A and your function parameters will be displayed. So long as those parameters have meaningful names you at-least have a viable prompt

For example, this:

=MyUDF( + CTRL + Shift + A

Turns into this:

=MyUDF(sPath, sFileName)

I just create a "help" version of the function. Shows up right below the function in autocomplete - the user can select it instead in an adjacent cell for instructions.

Public Function Foo(param1 as range, param2 as string) As String


Foo = "Hello world"


End Function


Public Function Foo_Help() as String


Foo_Help = "The Foo function was designed to return the Foo value for a specified range a cells given a specified constant." & CHR(10) & "Parameters:" & CHR(10)
& "  param1 as Range   :   Specifies the range of cells the Foo function should operate on." & CHR(10)
&"  param2 as String  :   Specifies the constant the function should use to calculate Foo"
&" contact the Foo master at master@foo.com for more information."


END FUNCTION

The carriage returns improve readability with wordwrap on. 2 birds with one stone, now the function has some documentation.

I tried @ScottK's approach, first as a side feature of my functional UDF, then as a standalone _Help suffix version when I ran into trouble (see below). In hindsight, the latter approach is better anyway--more obvious to a user attentive enough to see a tool tip, and it doesn't clutter up the functional code.

I figured if an inattentive user just typed the function name and closed the parentheses while he thought it over, help would appear and he would be on his way. But dumping a bunch of text into a single cell that I cannot format didn't seem like a good idea. Instead, When the function is entered in a cell with no arguments i.e.

   = interpolateLinear()
or
= interpolateLinear_Help()

a msgBox opens with the help text. A msgBox is limited to ~1000 characters, maybe it's 1024. But that's enough (barely 8^/) for my overly tricked out interpolation function. If it's not, you can always open a user form and go to town.

The first time the message box opened, it looked like success. But there are a couple of problems. First of course, the user has to know to enter the function with no arguments (+1 for the _Help suffix UDF).

The big problem is, the msgBox reopens several times in succession, spontaneously while working in unrelated parts of the workbook. Needless to say, it's very annoying. Sometimes it goes on until I get a circular reference warning. Go figure. If a UDF could change the cell formula, I would have done that to shut it up.

I don't know why Excel feels the need recalculate the formula over and over; neither the _Help standalone, nor the full up version (in help mode) has precedents or dependents. There's not an application.volatile statement anywhere. Of course the function returns a value to the calling cell. Maybe that triggers the recalc? But that's what UDFs do. I don't think you can not return a value.

Since you can't modify a worksheet formula from a UDF, I tried to return a specific string --a value --to the calling cell (the only one you can change the value of from a UDF), figuring I would inspect the cell value using application.caller on the next cycle, spot my string, and know not to re-display the help message. Seemed like a good idea at the time--didn't work. Maybe I did something stupid in my sleep-deprived state. I still like the idea. I'll update this when (if) I fix the problem. My quick fix was to add a line on the help box: "Seek help only in an emergency. Delete the offending formula to end the misery.

In the meantime, I tried the Application.MacroOptions approach. Pretty easy, and it looks professional. Just one problem to work out. I'll post a separate answer on that approach later.

A lot of dancing around the answer. You can add the UDF context help, but you have to export the Module and edit the contents in a text editor, then re-import it to VBA. Here's the example from Chip Pearson: Adding Code Attributes

I know you've accepted an answer for this, but there's now a solution that lets you get an intellisense style completion box pop up like for the other excel functions, via an Excel-DNA add in, or by registering an intellisense server inside your own add in. See here.

Now, i prefer the C# way of doing it - it's much simpler, as inside Excel-DNA, any class that implements IExcelAddin is picked up by the addin framework and has AutoOpen() and AutoClose() run when you open/close the add in. So you just need this:

namespace MyNameSpace {
public class Intellisense : IExcelAddIn {
public void AutoClose() {
}
public void AutoOpen() {
IntelliSenseServer.Register();
}
}
}

and then (and this is just taken from the github page), you just need to use the ExcelDNA annotations on your functions:

[ExcelFunction(Description = "A useful test function that adds two numbers, and returns the sum.")]
public static double AddThem(
[ExcelArgument(Name = "Augend", Description = "is the first number, to which will be added")]
double v1,
[ExcelArgument(Name = "Addend", Description = "is the second number that will be added")]
double v2)
{
return v1 + v2;
}

which are annotated using the ExcelDNA annotations, the intellisense server will pick up the argument names and descriptions.

There are examples for using it with just VBA too, but i'm not too into my VBA, so i don't use those parts.

@will's method is the best. Just add few lines about the details for the people didn't use ExcelDNA before like me.

Download Excel-DNA IntelliSense from https://github.com/Excel-DNA/IntelliSense/releases

There are two version, one is for 64, check your Excel version. For my case, I'm using 64 version.

Open Excel/Developer/Add-Ins/Browse and select ExcelDna.IntelliSense64.xll.

Insert a new sheet, change name to "IntelliSense", add function description, as https://github.com/Excel-DNA/IntelliSense/wiki/Getting-Started

Then enjoy! :)

Also you can use, this Macro to assign Descriptions to arguments and the UDF:

Private Sub RegisterMyFunction()
Application.MacroOptions _
Macro:="SampleFunction", _      '' Your UDF name
Description:="calculates a result based on provided inputs", _
Category:="My UDF Category", _  '' Or use numbers, a list in the link below
ArgumentDescriptions:=Array( _  '' One by each argument
"is the first argument.  tell the user what it does", _
"is the second argument.  tell the user what it does")
End Sub

Credits to Kendall and the original post here. For the UDF Categories