this post was submitted on 19 Jun 2023

50 points (91.7% liked)

Programming

17392 readers

147 users here now

Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!

Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.

Hope you enjoy the instance!

Rules

Follow the programming.dev instance rules
Keep content related to programming in some way
If you're posting long videos try to add in some form of tldr for those who don't want to watch videos

Wormhole

Follow the wormhole through a path of communities [email protected]

founded 1 year ago

MODERATORS

[email protected]

A quick tip for better variable names (programming.dev)

submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]

20 comments fedilink hide all child comments

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

top 19 comments

sorted by: hot top controversial new old

[–] [email protected] 9 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.

[–] [email protected] 10 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.

[–] [email protected] 1 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.

[–] [email protected] 5 points 1 year ago (2 children)

In languages with static and convenient type systems, I try to instead encode units as types. With clever C++ templating, you can even get implicit conversions (e.g. second -> hour) and compound types (e.g. meter and second types also generate m/s, m/s^2 and so on).

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

IIRC F# even has built-in support for units.

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

A good example is Go's time package. You'd normally express durations like 5 * time.Second and the result is a time.Duration. Under the hood, it's just an int64 nanoseconds, but you'd never use it as a plain nanoseconds. You'd instead use it like d.Seconds() to get whichever unit you desire.

[–] [email protected] 3 points 1 year ago (1 children)

Looks like Hungarian Notation

[–] [email protected] 7 points 1 year ago* (last edited 1 year ago)

Related: Making Wrong Code Look Wrong

TL;DR: there is good and bad Hungarian notation. Encoding types (like string or int) in variable names is bad. Encoding information that cannot be expressed in the type system is good. (Though with the development of type systems, more and more of those concepts can be moved into the types, keeping variable names clean.)

But as a Hungarian, I'm obviously a little biased :)

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

The better fix is to try to use types that represent those units or data types (e.g. duration instead of ms). Makes it harder to accidentally use the wrong units and documents the code / intent better.

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

fileSizeLimitGB

Surely its fileSizeLimitGiB

[–] [email protected] 2 points 1 year ago (1 children)

That seems akin to commenting. The problem with this approach is that text is not code. It's very easy to forget to change text. In that case it becomes the worst of both worlds, you have a variable name that actually misleads you.

Much safer than this is to encode this kind of information into the code itself in such a way the program won't compile of the types are incorrect.

[–] [email protected] 4 points 1 year ago

I understand what you mean, and I even agree with it, but just to be a little pedantic, variable names are code, or at least they are more code than comments or docs.

But yes, encoding units into the type system is a much better solution. It doesn't work however for config options, environment variables or CLI switches.

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

I think some of the modern languages handle this pretty well. Rust has algebraic data types thanks to its brilliant use of enums. Go has a similar type system. Taking the elapsedTime example from the post, for solving this duration related problem, a Rust programmer would use Duration::from_millis(millis) or Duration::from_secs(secs) and forget about the unit. It's a duration, that's what you wanna care about.

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

It's so annoying when you have to figure out what unit a variable is describing :(

[–] [email protected] 1 points 1 year ago (2 children)

But what if the FileSize can be „1G“, „1024M“, 518K“, etc.?

Documentation itself is much more important and modern IDEs and Editors will show you what to type in :)

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

Then use bytes

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

In that case I would call the variable fileSizeWithUnit and also document what the possible units are. I wouldn't say that documentation is categorically more important than good naming. Both are different aspects of good software development.

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

Variables, meh. As long as the code is clear, I don't mind too much about naming. For config options? Absolutely.

load more comments