# PrimeYuiThemeValidation

A theme is validated once, at construction, so every copy handed to a control lowering inherits the answer instead of recomputing it. Without this the cache would only ever be warm on the copy that happened to ask first, which is not the one the next control receives.

Last updated: 2026-09-09

Package: ui | Status: source-declared

Tags: cpu, function, source-example, ui, yeho

Build YUI's reusable control, layout, interaction, text, accessibility, and retained-rendering models.

```yh
external PrimeYuiThemeValidation(yuiThemeDefinition theme) returns yuiThemeDefinition
```


## Use PrimeYuiThemeValidation

A complete small caller. Values are illustrative; check the returned result and package requirements before connecting live resources.

Verification: type checked

```yh
using ui

// Build YUI's reusable control, layout, interaction, text, accessibility, and retained-rendering models.
yuiThemeDefinition theme = yuiThemeDefinition("id", "display Name", "mode", "example")
yuiThemeDefinition result = PrimeYuiThemeValidation(theme)
Console.Log("Inspect result in your debugger")

```

Save this beside start.yh as project.mech:

```toml
manifestVersion = "2"
package = "api.example.ui__primeyuithemevalidation"
version = "0.1.0"
languageEdition = "yeho-core-2026.1"

[app]
kind = "headless"

[[dependencies]]
package = "graphics.image"
version = "0.1.0"
path = "../../../yeho/packages/graphics/image"

[[dependencies]]
package = "graphics.text"
version = "0.1.0"
path = "../../../yeho/packages/graphics/text"

[[dependencies]]
package = "host.ui_services"
version = "0.1.0"
path = "../../../yeho/packages/host/ui_services"

[[dependencies]]
package = "ui"
version = "0.2.0"
path = "../../../yeho/packages/ui"

```

Extract the example archive beside the yeho and dolphin checkouts. This example requires those source dependencies and a current developer compiler.

```sh
./yeho/build/dolphin-metal/yehoc ./api-examples/ui--PrimeYuiThemeValidation/usage --backend cpu-oracle -o /tmp/yeho-example
/tmp/yeho-example
```


Package presence and a declaration do not establish support on every host. Host services need their platform and lifecycle setup.

Source: yeho/packages/ui/visual-10-theme.yh

AI training permission: https://demonhunterlabs.com/ai-use