2025, Nov 01 15:00

How to Cap Hope and Fear at 6 in a Python d12 Dice Roller: Guarded Increments and min() Clamping

Learn to cap Hope and Fear at 6 in a Python dice roller. Use guarded increments or min() clamping, avoid extra int casts, and prevent negatives when spending.

When you automate dice rolls for a tabletop mechanic that tracks two resources, it’s tempting to think you can “lock” a variable to a maximum value. In Python, though, there’s no built-in way to assign a hard cap directly to a variable. If you’re accumulating Hope and Fear up to 6 based on two d12 rolls, you need to code the limit explicitly.

Problem setup

Two d12s are rolled. If the Hope die beats the Fear die, Hope increases by 1. If the Fear die wins, Fear increases by 1. Neither resource may exceed 6. Here’s a minimal slice that increments without any cap, which allows the value to go past the limit:

if user_cmd == 'r':
    pos_d12 = int(random.randint(1, 12))
    neg_d12 = int(random.randint(1, 12))
    sum_roll = int(pos_d12) + int(neg_d12)
    print('You rolled {} with ...'.format(sum_roll))
    if pos_d12 > neg_d12:
        print('... hope')
        hope_pool += 1

What actually causes the issue

Python doesn’t enforce an upper bound on ordinary integers. That means increments will keep going as long as your code asks them to. To enforce a maximum, you must check the current value before increasing it or explicitly clamp the result to the maximum.

There’s also no need to cast the results of randint to int. The function already returns an integer. As documented:

Return a random integer N such that a <= N <= b. Alias for randrange(a, b+1).

Two reliable ways to cap the resource

The first way is a guarded increment. You only add 1 when the current value is strictly below the cap:

if pos_d12 > neg_d12:
    if hope_pool < 6:
        hope_pool = hope_pool + 1

The second way is to always attempt to add 1, then clamp the result using min so it never exceeds 6:

if pos_d12 > neg_d12:
    hope_pool = min(hope_pool + 1, 6)

If hope_pool is already 6, min(6 + 1, 6) evaluates to 6, so the value stays capped.

Integrated snippet with both resources capped

The following refactor applies the guarded increment to Hope and Fear and removes the unnecessary int casts on randint and sums:

if user_cmd == 'r':
    pos_d12 = random.randint(1, 12)
    neg_d12 = random.randint(1, 12)
    sum_roll = pos_d12 + neg_d12
    print('You rolled {} with ...'.format(sum_roll))
    if pos_d12 > neg_d12:
        print('... hope')
        if hope_pool < 6:
            hope_pool = hope_pool + 1
    if pos_d12 < neg_d12:
        print('... fear')
        if fear_pool < 6:
            fear_pool = fear_pool + 1
    if pos_d12 == neg_d12:
        print('Doubles! An extreme event')
        print('%s Hope, %s Fear' % (hope_pool, fear_pool))

If you prefer the clamping style, you can swap the guarded increments with min on both branches while keeping the rest identical:

if pos_d12 > neg_d12:
    print('... hope')
    hope_pool = min(hope_pool + 1, 6)
if pos_d12 < neg_d12:
    print('... fear')
    fear_pool = min(fear_pool + 1, 6)

Preventing negative values when spending a resource

When a resource is consumed, ensure it never drops below zero. A simple availability check is enough:

if user_cmd == 'h':
    if hope_pool > 0:
        hope_pool = hope_pool - 1
        print('%s Hope, %s Fear' % (hope_pool, fear_pool))
    else:
        print('No hope available')

Why this matters

Explicit caps keep game state consistent and predictable. They avoid silent overflows, make edge cases (like already-maxed resources) unambiguous, and keep counters from drifting into invalid ranges. That predictability is essential for a clean gameplay loop.

Conclusion

In Python, you don’t “set a maximum on a variable.” You enforce it with logic. For increments, either guard with a comparison or clamp with min. For decrements, verify there’s something to spend. Keep randint results as-is—they’re already integers—and your dice roller will behave exactly as intended while never exceeding the resource cap.

The article is based on a question from StackOverflow by Nienke and an answer by StandingDuck.