The long answer on when to use a function vs command

Phil Davis davis.phil at comcast.net
Wed Mar 15 01:39:44 EST 2006


Hi Tom,

Here are some simple ways I figure out whether to use a command or a 
function in a given situation.

A function name can naturally take on the role of a noun in a sentence. 
Or in RunRev terms, it can naturally fill the role of a containerName. A 
good function name can really improve the readability of the code in 
those places where it is used.

   put selectedTunes() into fld "tuneList"
   put cardObjectIDs("firstCard") into tObjectList
   if errorCount() > 3 then...

In each of the above cases, a function name takes the place of a 
subprocess that is probably secondary to the purpose of the calling 
handler. That secondary code is moved to a place of its own, where it 
can be appreciated for its value instead of cursed as a distraction, as 
it might be if it were coded inline. Without functions, code would be a 
lot harder to read.


A command name can be a short imperative sentence without the spaces:

   refreshMembersList
   closeCurrentScreen
   startMotor
   moveRobotArm "left",5 -- this one has 2 parameters

If at a given spot in your code, you can describe what needs to be done 
in a short sentence like the ones above, a command will probably serve 
well in that spot.


This isn't exactly what you asked for, but maybe it helps.

Phil Davis



Thomas McGrath III wrote:
> Hello listeroos,
> 
> Can someone give the long answer on when is it best to use a function  
> versus a command? I have a lot to write of both commands and  functions 
> and have been overly confusing myself. Please give at least  two 
> examples each with parameters and how to call/use them.
> 
> Much appreciated,
> 
> Tom
> 
> 
> Thomas J McGrath III
> 3mcgrath at adelphia.net
> 
> Lazy River Software™ - http://www.lazyriversoftware.com
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