Thread on Twitter: https://twitter.com/benjamincremer/status/1086327888717041664

IsNotInThePastValidation.php

<?php
// $clock implements Clock
// interface Clock
// {
//     public function now() : DateTimeImmutable;
// }

// setup
$startDate = Date::fromString('2019-01-04');

// variant 1A) Tell, Don't Ask
$isNotPast = $startDate->isNotInThePast($clock);

// variant 1B)
$isNotPast = (new IsNotInThePastValidator($clock))
  ->isNotInThePast($startDate);


// ==== Add Offset Support, Check if given Date is today in another Timezone
// Example: It's 2019-01-04 08:00 in UTC
// User Submitted 2019-01-03 as Checkindate
// Check if 2019-01-03 is still today for an earlier timezone.

// setup
$startDate = Date::fromString('2019-01-04');
$offset = '-0800';

// variant 2A) Tell, Don't Ask
$isNotPast = $startDate->isNotInThePast($clock, $offset);

// via @matthiasnoback
$isNotPast = $startDate->isNotInThePast($clock->now(), $offset);

// via @mathiasverraes https://twitter.com/mathiasverraes/status/1086356193847721990
$clock = new Clock($earliestTimezone)
!$clock->isInPast($someDate)
$clock->now()->isLaterThan($someDate)

// via @rosstuck  https://twitter.com/rosstuck/status/1086364229119152128
  SearchDate::basedOn($userInput, $clock) 
    
  // variant 2B)
$isNotPast = (new IsNotInThePastValidator($clock, $offset))
  ->isNotInThePast($startDate);

// variant 2C)
$isNotPast = (new IsNotInThePastValidator($clock))
  ->isNotInThePast($startDate, $offset);

Z_implementation.php

<?php
class IsNotInThePastValidator
{
    public function isNotInThePast(Clock $clock, string $offset): bool
    {
        $today = self::fromDateTime(
            $clock->now()->setTimezone(new \DateTimeZone($offset)
        );

        return $this->equals($today) || $this->isLaterThan($today);
    }
}
    
class IsNotInThePastValidator
{
    public function __construct(Clock $clock, string $offset)
    {
        $this->clock = $clock;
        $this->timezone = new \DateTimeZone($offset);
    }

    public function isNotInThePast(Date $date): bool
    {
        $today = Date::fromDateTime(
            $this->clock->now()->setTimezone($this->timezone)
        );

        return  $date->equals($today) || $date->isLaterThan($today);
    }
}