The Real Basics of Functions in ASP - Customer Spec Part 2

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Customer Spec part 2: "Ok John, that’s great, now we need to do it for all of these numbers too…."

You suddenly need to work out the result of hundreds of sums. But because we have a function that does all of the dirty work (okay, perhaps it’s not that dirty) you only need to add one line of code per calculation:

<%
function simplemaths(var1, var2)
result=var1+var2
' Add a new line to do the multiplication
result=result*10
response.write result & "<br />"
end function

call simplemaths(1, 2)
call simplemaths(1, 9)
call simplemaths(3, 4)
call simplemaths(1, 5)
%>

So you’re happily coding away, putting the final sum together when the customer calls you again:

"Erm, I’ve just realized – I need you to multiply all of the numbers by ten before you write them to the screen! Sorry!"

If you had hundreds of individual calculations then that could be a big task. If you have one function that does it all, then it’s easy!

<%
function simplemaths(var1, var2)
result=var1+var2
' Add a new line to do the multiplication
result=result*10
response.write result & "<br />"
end function

call simplemaths(2, 2)
call simplemaths(1, 2)
call simplemaths(1, 9)
call simplemaths(3, 4)
call simplemaths(1, 5)

input1=10
input2=20
call simplemaths(input1, input2)

%>

Pretty compelling, eh? So functions are the bee’s knees and re-usable, maintainable code will save us all. The functions that developers have as a resource act as the foundations for the applications that they produce and the ability to control these functions is a valuable one. The concept relies upon the fact that you and your code shouldn’t really have to worry about how to achieve the specific task – because after you’ve coded it once you never need to code it again. It’s a little black-box of code and all you need to know is how to use it (not how it works inside). This description is edging us gently towards the concepts of Object-Orientated (OO) Design and if you’d like to stick with me through the series of articles we’ll attempt to cover this in more detail – by developing more real-life examples and ideally code that we all can use and re-use!