'Data' sucks

One of the two hard things about programming is naming things, and as programmers we spend a fair bit of time thinking about what we name different 'things'. Having a consistently good naming scheme across a large codebase can significantly speed up development, and having confusing names will slow it down.

Let's say the "badness" of a variable name is: "how badly named something is" multiplied by "how often you see the bad name". I think the worst variable name in all of programming is the word "data".

Why it sucks:

• It doesn't mean anything. Everything is data.
• I guarantee you can think of a better name. You're being lazy.
• It is an invariable noun. Like the word "sheep", it could mean one sheep, or many sheep. (Some might argue that the singular is "datum" but that's pretty uncommon). So you can't even reason about whether the "data" is iterable or not.

If I run the query "(data, language:Python" in GitHub across all public repos, we can look at some nice Python examples of functions where "data" is the first arg. Here is the first example:

def imgcat(data, lines=-1):

See what I mean? What is data? What type is it? What does the function do? 🤷

Since Python has type hints, and everyone who endeavors to actually write good Python should be using them, let's do ourselves a favour and change our search to "(data: language:Python" so it only finds typed examples.

async def stream_offline(data: dict):

What's data? I mean, it's a dictionary, but since it's only half typed, and not something strict like a dict[str, int] or something, once again, it could technically be anything.

Or this great example!

def calc_zscore(data: np.ndarray) -> np.ndarray:
    """
    计算数据的z分数。

Nice, "data" is actually a numpy array! A strict type! However, np.ndarrays are actually quite spicy multi-dimensional containers, so you usually want to specify what sort of data array you're expecting unless a "z-score" is something that applies to all ndarrays regardless of size and dimensionality. What does this function do anyway? Let's translate the comment using ChatGPT:

I don't know what I expected.

Let's say we have a great example like the following.

from dataclasses import dataclass

@dataclass
class JohnsSpecialObject:
    bing: int
    bong: str

def do_something(data: JohnsSpecialObject) -> None:
    pass

Now we know exactly what data is! In this case though, wouldn't it make more sense to write:

def do_something(johns_special_object: JohnsSpecialObject) -> None:
    pass

instead of calling it "data"?

If I find myself ever using the word "data" in code, I do some more thinking and come up with a better name. Please for everyone's sake, you should do the same.