Thread by @championswimmer

Something common to be found in large Android codebases is dimens.xml file with contents that look like this

This is a major 🚩🚩🚩🚩

It originates from overzealous developers not wanting to *hardcode pixel/dp in layout XMLs*, but it very counterproductive.

We need not be grammar-nazi like in our approach and go for a hard-rule on never to write android:layout_height=12dp kind of code, because from a readability perspective, there is no advantage of turning fig.1 into fig.2

@dimen/_24dp has to be 24dp right? What is the point?

In fact, now we have opened ourselves to a whole different level of subterfuge in the code in the future.

What if, some day, (by mistake, not deliberately), someone changes these values. Perfectly possible under time-constraint, doing last-minute UI fixes.

Voila now, "@dimen/_38dp" actually means 48dp. We just turned the situation way worse. Nothing means what it says anymore.

This is waaaaay worse than just hardcoding 38dp or 48dp in the ImageView or wherever.

So what is a good approach you ask ?

Well there are 2 situations

1. the dimension can be semantically named, if so then do it and use a dimen.xml argument
2. it is really ad-hoc in nature, cannot have a semantic name. Then just hardcode the dp value.

Addendum: What is a semantic name ?

Something like "fragment_vertical_padding" - the const you use paddings of all your fragments.
Or "heading_text_size" - the const you use for text size of all your heading texts.