Tips for naming variables

http://makinggoodsoftware.com/2009/05/04/71-tips-for-naming-variables/

by albertoG • 17 years ago

11 22 17 years ago

makinggoodsoftware.com

babo• 17 years ago

Stopped reading here: "Good example: daysFromDateRangeStartToEnd".

mrduncan• 17 years ago

Seems like the author didn't take his own advice - "2.- The variable name has to be as short as possible."

albertoG2• 17 years ago

Hi babo,

you are absolutely right with your observation, that variable name its just a bad example, I have just edited the post and I have changed its name to daysDateRange.

Thanks for your feedback

pwim• 17 years ago

Neither your original daysFromDateRangeStartToEnd nor daysDateRange seem to capture what it is supposed to represent. Perhaps if it was seen in context, it would be understandable, but by itself I do not think it is a good example.

mojuba5• 17 years ago

  void swap(int* x, int* y)
    { int t = *x; *x = *y; *y = t; }

Small blocks with very obvious code are perfectly Ok to have short variable names in. All other rules in this post can be criticized as easily.

Hence, rule #8: forget about the previous rules, just be a smart coder.

sethg2• 17 years ago

Indeed, I think one very useful rule for naming variables is "the length of the name should be proportional to the scope". If you're iterating through a list of objects representing unfilled orders, it's OK to do this:

  for uo in unfilledOrdersIterator():
      oid = uo.id
      status = uo.status
      email = uo.customer.email
      sendEmail(email, "Your order %s is in status %s" % (oid, status))

But if there's a 200-line method that does all sorts of other things with a single unfilled order, then calling the order "uo" is probably a bad idea.

pp• 17 years ago

Shouldn't there NOT be 200-line methods in the first place?

bkudria2• 17 years ago

Um, have you ever written code like this in a real program? Honestly? Why would you ever want to swap variables?

(I mean, I remember doing this thing in TI-83+ BASIC, where valid variable names were limited to the letters of the alphabet ...)

mojuba5• 17 years ago

Check out some popular sorting algorithms, those that do the job "in place", i.e. without additional memory allocation.

Deestan• 17 years ago

> Example. If your customer just considers “order” an “order” that has been approved, don’t call “order” to a non approved one in your code, call it “nonApprovedOrder”.

Doesn't this violate his rule #5?

albertoG2• 17 years ago

Hi Deestann, good catch, I should have stressed that these are guidelines not rules, what I meant is if possible use positive logic, but it fits better the negative, use the negative one.

Thanks for the comment

ashleyw• 17 years ago

Ideally should be using short methods, so what's wrong with using generic names?

Daniel_Newby2• 17 years ago

"Don´t use negative logic for your variable names."

Obviously written by a software weenie who lives far, far away from the actual hardware. ;-) (Digital logic often uses active-low signals for good electrical reasons. And some purely historic reasons: do memory chips actually need to power up in the activated state?)

wlievens2• 17 years ago

What what what?

Daniel_Newby2• 17 years ago

Many circuits work with Boolean values that are true in the 0 state, and false in the 1 state: negative logic. That had better be reflected in the variable names.

Tips for naming variables

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