// Copyright 2018-2025 the Deno authors. MIT license.
// This module is browser compatible.
import { getLogger } from "./get_logger.ts";
import type { GenericFunction } from "./logger.ts";
import "./setup.ts";
export type { GenericFunction };
/**
* Log at the warning level.
*
* This function is a pass-through to the default logger's `warn` method. By
* default, the default logger is configured to use {@linkcode console.log} and
* print in yellow text.
*
* @template T The type of the message to log.
* @param msg The message to log.
* @param args Arguments to be formatted into the message.
* @returns The message that was logged.
*
* @example Usage
* ```ts
* import { warn } from "@std/log/warn";
* import { assertEquals } from "@std/assert/equals";
*
* assertEquals(warn("This is a warning message."), "This is a warning message.");
* // Prints: "WARN This is a warning message."
*
* assertEquals(warn(() => "This is a warning message."), "This is a warning message.");
* // Prints: "WARN This is a warning message."
* ```
*/
export function warn<T>(msg: () => T, ...args: unknown[]): T | undefined;
/**
* Log at the warning level.
*
* This function is a pass-through to the default logger's `warn` method. By
* default, the default logger is configured to use {@linkcode console.log}.
*
* @template T The type of the message to log.
* @param msg The message to log.
* @param args Arguments to be formatted into the message.
* @returns The message that was logged.
*
* @example Usage
* ```ts
* import { warn } from "@std/log/warn";
* import { assertEquals } from "@std/assert/equals";
*
* assertEquals(warn("This is a warning message."), "This is a warning message.");
* // Prints: "WARN This is a warning message."
*
* assertEquals(warn(() => "This is a warning message."), "This is a warning message.");
* // Prints: "WARN This is a warning message."
* ```
*/
export function warn<T>(
msg: T extends GenericFunction ? never : T,
...args: unknown[]
): T;
export function warn<T>(
msg: (T extends GenericFunction ? never : T) | (() => T),
...args: unknown[]
): T | undefined {
// Assist TS compiler with pass-through generic type
if (msg instanceof Function) {
return getLogger("default").warn(msg, ...args);
}
return getLogger("default").warn(msg, ...args);
}
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