src/Carbon/CarbonPeriod.php
public function setStartDate($date, $inclusive = null)
    {
        if (!$date = call_user_func([$this->dateClass, 'make'], $date)) {
            throw new InvalidArgumentException('Invalid start date.');
        }

        $this->startDate = $date;

        if ($inclusive !== null) {
            $this->toggleOptions(static::EXCLUDE_START_DATE, !$inclusive);
        }

        return $this;
    }
public function setStartDate($date, $inclusive = null)
    {
        if (!$date = call_user_func([$this->dateClass, 'make'], $date)) {
            throw new InvalidArgumentException('Invalid start date.');
        }

        $this->startDate = $date;

        if ($inclusive !== null) {
            $this->toggleOptions(static::EXCLUDE_START_DATE, !$inclusive);
        }

        return $this;
    }
public function setStartDate ( $ date , $ inclusive = null ) { if ( ! $ date = call_user_func ( [ $ this -> dateClass , 'make' ] , $ date ) ) { throw new InvalidArgumentException ( 'Invalid start date.' ) ; } $ this -> startDate = $ date ; if ( $ inclusive !== null ) { $ this -> toggleOptions ( static :: EXCLUDE_START_DATE , ! $ inclusive ) ; } return $ this ; }
Change the period start date.

@param DateTime|DateTimeInterface|string $date
@param bool|null                         $inclusive

@throws \InvalidArgumentException

@return $this
Change the period start date .