BitLogger/docs/api/style-tag-registry-set-tag.md

name, group, category, update-time, description, key-word

name	group	category	update-time	description	key-word
style-tag-registry-set-tag	api	formatter	20260613	Add or override a named style tag in a StyleTagRegistry.	style registry tag public

Style-tag-registry-set-tag

Add or override one named style tag inside a StyleTagRegistry. This is the main mutation helper for building custom formatter tag vocabularies in code.

Interface

pub fn StyleTagRegistry::set_tag(
  self : StyleTagRegistry,
  name : String,
  style~ : TextStyle = text_style(),
  fg~ : String? = None,
  bg~ : String? = None,
  bold~ : Bool = false,
  dim~ : Bool = false,
  italic~ : Bool = false,
  underline~ : Bool = false,
) -> StyleTagRegistry {

input

• self : StyleTagRegistry - Registry to update.
• name : String - Tag name to define or replace.
• style : TextStyle - Base style value to store before overlay options are applied.
• fg : String? - Optional foreground color override.
• bg : String? - Optional background color override.
• bold : Bool - Whether to enable bold in the stored style.
• dim : Bool - Whether to enable dim in the stored style.
• italic : Bool - Whether to enable italic in the stored style.
• underline : Bool - Whether to enable underline in the stored style.

output

• StyleTagRegistry - The same registry value after the named entry is updated.

Explanation

Detailed rules explaining key parameters and behaviors

• The tag name is normalized before storage, so lookup is case-insensitive in practice.
• The explicit fg, bg, and boolean flags are merged on top of the supplied style value.
• Calling set_tag(...) for an existing name replaces that entry with the merged result.
• The method returns the registry itself so calls can be chained while building formatter configuration.

How to Use

Here are some specific examples provided.

When Need A Custom Semantic Tag

When text output should recognize a project-specific tag name:

let tags = style_tag_registry()
  .set_tag("accent", fg=Some("#4cc9f0"), bold=true)

In this example, <accent>...</> becomes available to formatters that use the registry.

When Need To Start From An Existing Style

When a tag should reuse a prepared TextStyle and then tweak one field:

let base = text_style(fg=Some("#22cc88"))
let tags = style_tag_registry().set_tag("success", style=base, underline=true)

In this example, underline is layered on top of the base style value.

Error Case

e.g.:

• If style markup is disabled in the formatter, defining tags here has no visible effect on rendered output.

• If the same tag name is set multiple times, the latest stored value wins.

Notes

1. Use this method when custom tag definitions should live in a local registry instead of the global one.

2. define_alias(...) is the better fit when one tag name should mirror an existing tag exactly.