I'm developing an application with Python. I want to have a Boolean variable that represent whether something is buy or sell but I'm not sure how I should name it. Here are my current ideas:

  • isBuy
  • isSell
  • buy_sell
  • sell_buy
  • buy1_sell0

actually I like the last one the most although it's somehow the ugliest because it tells you all you need to know about it with certainty. However I thought I'd ask some more experienced people to see what is the actual python convention for such situations.

  • 9
    Or maybe the name is less important if you use an enum instead of a boolean?
    – amon
    Commented May 25, 2018 at 10:02
  • An enum is likely best. IsBuy or isSell is just about acceptable. Buy_sell and the others are just awful. You might as well have “isBuyOrSell” which always returns true.
    – gnasher729
    Commented Nov 18, 2022 at 17:40

2 Answers 2


Don't use a Boolean. Use an enum. E.g TransactionType with instances Buy and Sell.

That is unambiguous and far easier to understand.

If you want to persist the data efficiently, the boolean can be a good solution as long as there are only two instances in the enum. However, your code need not be efficient at that level of detail (that's the interpreters job); it needs to be very understandable. The enum achieves that goal far better.

  • Additionally, an enum gives you the option to easily extend the data type in case a new option needs to be added, e.g. "Lend". Commented May 25, 2018 at 15:17
  • Another bonus is that you can add logic to the enum. Example sign(), taxCode(), etc.
    – Borjab
    Commented Nov 18, 2022 at 11:33
  • @Borjab: depends on the language. It's possible in Python and Java, but in most other languages, enums cannot have functionality. Commented Nov 18, 2022 at 12:07
  • Also possible to add logic to enums in PHP, where enums are really special types of classes & objects.
    – bdsl
    Commented Nov 18, 2022 at 12:28

You should use is or has keyword in prefix to show that it is a Boolean variable. So, according to me first and second variable names are preferable instead of other variables as it clearly shows the meaning of the variable. Some of the built-in boolean variable name are as follows:


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