:sig
DValue* unit_call(String file_name, String function_name, DValue* call_param = null)

:params
file_name : UCE file to load and execute
function_name : name of the function to invoke
call_param : optional, call parameter
return value : DValue* returned from function

:see
>ob
unit_load
unit_render
unit_info
1_RENDER
1_COMPONENT

:content
Calls an exported function inside another UCE file.

Use `unit_call()` when you need structured data exchange between units rather than rendered HTML output.

The callee must expose an `EXPORT` function whose name matches `function_name`. Arguments are passed through `call_param`, and the return value is a `DValue*` owned by the callee.

`unit_call()` also understands the request-bound UCE entrypoint names:

- `RENDER`
- `RENDER:NAME`
- `COMPONENT`
- `COMPONENT:NAME`
- `ONCE`
- `INIT`

When `function_name` matches one of those macro-style entrypoints, `unit_call()` does not look for a plain `EXPORT DValue* ...` function. Instead, it translates the name to the generated C++ symbol, uses the current `Request` context, and passes `call_param` into `context.props`, matching the normal component invocation model.

For `RENDER...` and `COMPONENT...`, the unit's `ONCE(Request& context)` hook is still honored automatically before the selected handler runs.

Example:


Calling a named component handler through `unit_call()`:


Calling a page render handler through `unit_call()`:


:example
unit_call("examples/sample_unit.uce", "doc_greet");