Coding Style

This page contains Best Practice guidelines for styling code.

Guidelines

Components:
- Name specs consistently with NAMEComponentSpec to generate a component called NAMEComponent.
- The ComponentContext argument should be simply called c to make the layout code less verbose and more readable.
Resource Types - where appropriate, use resource types, such as ResType.STRING, ResType.COLOR, ResType.DIMEN_SIZE, to make it easier to set prop values from Android resources.
Props:
- Declare all required props first then the optional ones (optional = true).
- Declare common props (props defined for all Components on Component.Builder) after the component's own props.
Enums - use static imports on all layout Enums (such as YogaEdge, YogaAlign, YogaJustify) to reduce layout code and make it more readable.
Conditionals - use inline conditionals on optional children to keep the layout construction code fluent if possible.
Child Container - if constructing a child container, add the container in the following line. This gives the code a layout like construction.
Lifecycle methods - such as @OnCreateLayout, should be static and package-private.

The following snippet is an example of an application of the Litho Best Practice coding style:

@LayoutSpec
class MyComponentSpec {

  @OnCreateLayout
  static Component onCreateLayout(
      ComponentContext c,
      @Prop(resType = STRING) String title,
      @Prop(optional = true) Drawable image) {

  return Row.create(c)
      .alignItems(CENTER)
      .paddingRes(R.dimen.some_dimen)
      .child(
          Image.create(c)
              .drawable(image)
              .width(40)
              .height(40)
              .marginRes(RIGHT, R.dimen.my_margin))
      .child(TextUtils.isEmpty(title) ? null :
          Text.create(c)
              .text(title)
              .textColorAttr(R.attr.textColorTertiary)
              .marginDip(5)
              .flexGrow(1f))
      .build();
  }
}

Guidelines​

Guidelines