"Limiting the Range of a Number": Harlowe (v2.0)

Summary

This recipe demonstrates how to limit a numeric variable to a value between a set range. This process is commonly known as clamping.

The example adds a clamp() function to the existing built-in Math global JavaScript object, which can then be called to achieve the desired result.

Note: The example also adds a clamp() function to the built-in Number global JavaScript object, which the new Math.clamp() function uses internally. However, due to how Harlowe implements variables, the .clamp() function can't be used directly within a (set:) macro.

Twee Code

:: StoryTitle
Limiting the range of a number in Harlowe

:: UserScript [script]
(function () {

/*
Returns the number clamped to the specified bounds.

WARNING:
Due to how Harlowe implements variables you can NOT call this function directly,
you must use the Math.clamp() function instead.
*/
Object.defineProperty(Number.prototype, 'clamp', {
configurable : true,
writable     : true,

value(/* min, max */) {
if (this == null) { // lazy equality for null
throw new TypeError('Number.prototype.clamp called on null or undefined');
}

if (arguments.length !== 2) {
throw new Error('Number.prototype.clamp called with an incorrect number of parameters');
}

var min = Number(arguments);
var max = Number(arguments);

if (min > max) {
var tmp = min;
min = max;
max = tmp;
}

return Math.min(Math.max(this, min), max);
}
});

/*
Returns the given numerical clamped to the specified bounds.

Usage:
→ Limit numeric variable to a value between 1 and 10 inclusive.
(set: \$variable to Math.clamp(\$variable, 1, 10))

→ Limit result of mathematical operation to a value between 1 and 10 inclusive.
(set: \$variable to Math.clamp(\$variable + 5, 1, 10)_
*/
Object.defineProperty(Math, 'clamp', {
configurable : true,
writable     : true,

value(num, min, max) {
var value = Number(num);
return Number.isNaN(value) ? NaN : value.clamp(min, max);
}
});

})();

:: Start
Initialise the numeric variable to a value with the range you want.
eg. between ''1'' and ''10'' inclusive.
&#40;note: You don't need to use the //Math.clamp()// funtion at this point.&#41;\

(set: \$valueToClamp to 5)
''Current value'': \$valueToClamp

Increase the number to a value that is ''within'' the desired range.
eg. Add 1 to the current value.\

(set: \$valueToClamp to Math.clamp(\$valueToClamp + 1, 1, 10))
''New value'': \$valueToClamp

Try to increase the number to a value that is ''outside'' the desired range.
eg. Add 100 to the current value.\

(set: \$valueToClamp to Math.clamp(\$valueToClamp + 100, 1, 10))
''New value'': \$valueToClamp

Decrease the number to a value that is ''within'' the desired range.
eg. Minus 5 from the current value.\

(set: \$valueToClamp to Math.clamp(\$valueToClamp - 5, 1, 10))
''New value'': \$valueToClamp

Try to decrease the number to a value that is ''outside'' the desired range.
eg. Minus 100 from the current value.\

(set: \$valueToClamp to Math.clamp(\$valueToClamp - 100, 1, 10))
''New value'': \$valueToClamp