this post was submitted on 19 Jun 2023
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Programming

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A quick tip for better variable names (self.programming)
submitted 1 year ago* (last edited 1 year ago) by sisyphean to c/programming
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Whenever you store a value that has a unit in a variable, config option or CLI switch, include the unit in the name. So:

  • maxRequestSize => maxRequestSizeBytes
  • elapsedTime => elapsedSeconds
  • cacheSize => cacheSizeMB
  • chargingTime => chargingTimeHours
  • fileSizeLimit => fileSizeLimitGB
  • temperatureThreshold => temperatureThresholdCelsius
  • diskSpace => diskSpaceTerabytes
  • flightAltitude => flightAltitudeFeet
  • monitorRefreshRate => monitorRefreshRateHz
  • serverResponseTimeout => serverResponseTimeoutMs
  • connectionSpeed => connectionSpeedMbps

EDIT: I know it’s better to use types to represent units. Please don’t write yet another comment about it. You can find my response to that point here: https://programming.dev/comment/219329

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[–] [email protected] 13 points 1 year ago* (last edited 1 year ago) (2 children)

Those are just types. You shouldn't write types in the names. It's called Hungarian Notation, but it's just redundant. If you need to check the type of a variable, hover over it and your IDE should tell you that temperatureThreshold is type DegreesCelsius. No need to add extra cruft. There's also a question of how specific everything needs to be.

It's also especially problematic if you later refactor things. If you change units, then you have to rename every variable.

Plus, variables shouldn't really be tied to a specific unit. If you need to display in Fahrenheit, you ideally just pass temperatureThreshold and it converts types as needed. A Temperature type that that has degreesF() and degreesC() functions is even cleaner. Units should just be private to the type's struct.

[–] sisyphean 16 points 1 year ago* (last edited 1 year ago) (1 children)

I absolutely agree. But:

  • sometimes you need to modify existing code and you can't add the types necessary without a giant refactoring
  • you can't express units with types in:
    • JSON/YAML object keys
    • XML tag or attribute names
    • environment variable names
    • CLI switch names
    • database column names
    • HTTP query parameters
    • programming languages without a strong type system

Obviously as a Hungarian I have a soft spot for Hungarian notation :) But in these cases I think it's warranted.

[–] [email protected] 2 points 1 year ago

Not sure what languages you commonly work with, but in good modern languages you can simply declare "feet" as an alias of integer (or double?), and no refactoring would be required.

And any good toolchain to parse / generate JSON/etc can absolutely get the types right.

[–] JackbyDev 5 points 1 year ago

There are plenty of times where the type is just something generic like an integer and making a wrapper type is not worth the effort and this is a useful approach.