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Reference Guide: What does this symbol mean in PHP? (PHP Syntax)（25个回答）
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4天前关闭。
从手动可变长度参数列表中，应该只有一个可变长度参数作为函数的最后一个参数。
但是为什么这个opentelemetry-php api function：return $c(...$a, ...($a = []));有两个？

function trace(SpanInterface $span, Closure $closure, iterable $args = [])
{
    $s = $span;
    $c = $closure;
    $a = $args;
    unset($span, $closure, $args);

    $scope = $s->activate();

    try {
        /** @psalm-suppress InvalidArgument */
        return $c(...$a, ...($a = []));
    } catch (Throwable $e) {
        $s->setStatus(StatusCode::STATUS_ERROR, $e->getMessage());
        $s->recordException($e, ['exception.escaped' => true]);

        throw $e;
    } finally {
        $scope->detach();
        $s->end();
    }
}

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