Function Fn 

pub fn Fn<R: Runtime>(
    _ApplicationHandle: &AppHandle<R>,
    MethodName: &str,
    Parameters: Value,
) -> Result<MappedEffect, String>

Maps a string-based method name (command or RPC) to its corresponding effect constructor, returning a boxed closure (MappedEffect) that can be executed by the ApplicationRunTime.

Arguments

• ApplicationHandle: Tauri app handle for accessing state
• MethodName: The command/RPC method name to map
• Parameters: JSON value containing parameters for the effect

Returns

Result<MappedEffect, String> - either a boxed async closure or an error if the command is unknown