5g: Source Structure - Basic

Documentation Block - This section is where we can add a comment that appears in the Name Manager. We also add our revision log. The revision log also serves as a version identifier. 

Change:

• <enter function's name here with λ> to your function's name. Place a lambda character (λ) at the end to help differentiate custom functions from Excel's functions. Do not include the angled brackets (< >).

• <enter a brief description of the function's purpose> to a sentence or two explaining what this function does.

• <Mmm dd yyyy> to the date this was edited..

• <Your Name> Your name> to your name

• <What changed> to a brief description of what was done. If this is when the function was created, we suggest either a copyright notice or "original development". 

Function Declaration - Here is where we declare our function's name. 

Change:

• FunctionNameλ to your function's name. Use the lambda symbol (λ) at the end of the function name to draw attention to the fact this is a user defined function. Excel's IntelliSense will make it so no one has to enter that symbol when using our function.

Argument Declarations - All function arguments must be declared here. Argument names must be concise and meaningful to strangers. 

All arguments must be enclosed in square brackets to enable inline help to function. To Excel, this makes function arguments optional which allows users to enter the function name without any arguments. When the required arguments are missing, our function can use that to trigger the inline help.

Change:

• [ArgumentX> to your function's arguments. Enclose all arguments in square brackets here. 

Omitted Required Arguments Test - With all arguments declared as optional, we must test for omitted required arguments, and if any required arguments are missing, we must display inline help. In this example Argument1 and Argument2 are required.

Change:

• [ArgumentX] to your function's required arguments. Add all required arguments.

Inline Help - All Excel functions have inline help. At this time, Microsoft has no facility for adding hypertext pop-up inline help so we came up with a way to display inline help in Excel's cells using the TEXTSPLIT() function. To control TEXTSPLIT's behavior when text contains commas, we replace TEXTSPLIT's default delimiters with → for columns, and ¶ for rows.

Change:

• <FunctionNameλ> to your function's name. 

• ArgumentX to your function's arguments. Be sure to enclose optional arguments in square brackets here.

• <Copy the functions description to here> to the description in the documentation block.

• <enter function's webpage URL here (if any)> to a webpage dedicated to explaining this function (if any exists).

• <Author's initials> to your initials or your company's name

• Mmm dd yyyy to the date this was edited..

• <argument description> to what is appropriate to describe each argument.

• <Default value> to each optional argument's default value

Defaults and Named Constants - In this example, Argument3 is optional.

Change:

• "default value" to whatever is required for your default value. Any optional arguments must be provided defaults and If we find ourselves adding hard coded numbers to our formulas, like 12 for 12 months, we urge creators to name those values in this section and use the name, rather than the value, in our formulas.

Procedure - This is where we put the formulas that provide our function's functionality. Change LET step names and "enter formulas starting here" to your LET step names and formulas. All LET steps must have clear and concise names. Use mnemonics for LET step names with LET step names would otherwise be more than about 10 characters..

Change:

• LET Step name to clear and concise names for each formula 

• "enter formulas here" to your function's formulas.

• "enter last formula here" to your function's last formula

Function Result - At the end of the procedure, LET allows us to have a formula as its last step; however, to make debugging functions easier, 5g requires the last LET step to be the name of the last formula. This allows us, when debugging, to change this last name to any of the other LET step names to see what they produce.