Prevent child classes from redefining methods - Revision history

Zhell at 16:13, 7 February 2026

2026-02-07T16:13:01Z

Zhell at 15:54, 7 February 2026

2026-02-07T15:54:43Z

Zhell at 05:29, 7 February 2026

2026-02-07T05:29:16Z

Zhell at 04:51, 30 January 2026

2026-01-30T04:51:26Z

Zhell at 04:50, 30 January 2026

2026-01-30T04:50:13Z

Zhell at 04:49, 30 January 2026

2026-01-30T04:49:57Z

Zhell at 04:49, 30 January 2026

2026-01-30T04:49:41Z

Zhell at 04:42, 30 January 2026

2026-01-30T04:42:34Z

Zhell at 04:41, 30 January 2026

2026-01-30T04:41:13Z

Zhell: Created page with " class MyParentTokenClass extends Token { init(amount, owner) { const extended = this.constructor != MyParentTokenClass..."

2026-01-30T04:38:36Z

Created page with "<syntaxhighlight lang="javascript"> class MyParentTokenClass extends Token { init(amount, owner) { const extended = this.constructor != MyParentTokenClass..."

New page

<syntaxhighlight lang="javascript">

class MyParentTokenClass extends Token {

init(amount, owner) {
const extended = this.constructor != MyParentTokenClass
if (!extended) throw new Error('This contract must be extended');

super.init(amount, owner);

// --- prevent redefining send() in child classes

// basic version (prevent overriding only one method like "send")
// const proto = Object.getPrototypeOf(this);
// if (proto.send !== MyParentTokenClass.prototype.send) {
// throw new Error(`Method 'send' cannot be overridden by class ${this.constructor.name}`);
// }

// advanced version, for ex to prevent overriding all methods
function getDeepPropertyNames(obj) {
const props = new Set(); // set to keep unique names
let current = obj;
while (current && current !== Object.prototype) {
// Get all string properties (including non-enumerable ones)
const ownProps = Object.getOwnPropertyNames(current);
ownProps.forEach(prop => props.add(prop));
// Move one level up the chain
current = Object.getPrototypeOf(current);
}
return Array.from(props);
}
const childProto = Object.getPrototypeOf(this);
const parentProto = Object.getPrototypeOf(childProto);
const childMethods = Object.getOwnPropertyNames(parentProto);
// console.log("childMethods:", childMethods);
const parentMethods = getDeepPropertyNames(MyParentTokenClass.prototype);
// console.log("parentMethods:", parentMethods)
let overriddenMethods = childMethods.filter(method =>
parentMethods.includes(method) && method !== 'constructor'
// && method !== 'init' // unsure if we want to allow overriding init() or not, might depend on case
);
console.log("overriddenMethods:", overriddenMethods);
if (overriddenMethods.includes('send')) {
throw new Error(
`Error: Subclass "${this.constructor.name}" is not allowed to override the critical methods: [${overriddenMethods}]. ` +
`These methods must remain as implemented in the base class.`
);
}
// console.log(`-- No forbidden overrides detected in "${this.constructor.name}". --\n`);
}
}
</syntaxhighlight>

← Older revision		Revision as of 16:13, 7 February 2026
Line 13:		Line 13:

	This could be a new type of Runcraft contracts, that we may call "clone contracts" since all children are a guaranteed clone of the parent (except for properties).		This could be a new type of Runcraft contracts, that we may call "clone contracts" since all children are a guaranteed clone of the parent (except for properties).
		+
		+	Also, properties could be used to turn on/off specific features in the contract.

	== full code for preventing overrides ==		== full code for preventing overrides ==

@@ Line 1: / Line 1: @@
 Here is a solution that we found to prevent child classes (using extends) to override some specific methods from your parent class.
-Note that this has limitations though: it does NOT prevent someone to create a new function and implement any behavior they want. So while they may not be able to change how send() works, they can still create send2() and do anything they want in it.
+Beware that this has limitations though: it does NOT prevent someone to create a new function and implement any behavior they want. So while they may not be able to change how send() works, they can still create send2() and do anything they want in it.
 <syntaxhighlight lang="javascript">
@@ Line 11: / Line 10: @@
 </syntaxhighlight>
-and changing class properties before deploy. This could be a new type of Runcraft contracts, that we may call "clone contracts" since all children are a guaranteed clone of the parent (except for properties).
+and changing class properties before deploy.
 == full code for preventing overrides ==

@@ Line 13: / Line 13: @@
 and changing class properties before deploy. This could be a new type of Runcraft contracts, that we may call "clone contracts" since all children are a guaranteed clone of the parent (except for properties).
-full code for preventing overrides
+== full code for preventing overrides ==
 <syntaxhighlight lang="javascript">

@@ Line 13: / Line 13: @@
 and changing class properties before deploy. This could be a new type of Runcraft contracts, that we may call "clone contracts" since all children are a guaranteed clone of the parent (except for properties).
-# full code for for preventing overrides
+full code for preventing overrides
 <syntaxhighlight lang="javascript">

@@ Line 11: / Line 11: @@
 </syntaxhighlight>
-and changing class properties before deploy
+and changing class properties before deploy. This could be a new type of Runcraft contracts, that we may call "clone contracts" since all children are a guaranteed clone of the parent (except for properties).
 <syntaxhighlight lang="javascript">

@@ Line 29: / Line 29: @@
          // basic version (prevent overriding only one method like "send")
-         // /!\ beware this actually isnt strong enough bc it only checks at 1 level, so 2 extends are enough to bypass it
+         // this will allow deploy but break on instance creation (as expected)
          // const proto = Object.getPrototypeOf(this);
          // if (proto.send !== MyParentTokenClass.prototype.send) {

@@ Line 29: / Line 29: @@
          // basic version (prevent overriding only one method like "send")
          // const proto = Object.getPrototypeOf(this);
          // if (proto.send !== MyParentTokenClass.prototype.send) {
@@ Line 34: / Line 35: @@
          // }
-         // advanced version, for ex to prevent overriding all methods
+         // advanced version -> we check the entire prototype chain to avoid any bypass
          function getDeepPropertyNames(obj) {
              const props = new Set(); // set to keep unique names

← Older revision		Revision as of 04:42, 30 January 2026
Line 10:		Line 10:

	</syntaxhighlight>		</syntaxhighlight>
		+
		+	and changing class properties before deploy
		+
		+	Here is the full code:

← Older revision		Revision as of 04:41, 30 January 2026
Line 1:		Line 1:
		+	Here is a solution that we found to prevent child classes (using extends) to override some specific methods from your parent class.
		+
		+	Note that this has limitations though: it does NOT prevent someone to create a new function and implement any behavior they want. So while they may not be able to change how send() works, they can still create send2() and do anything they want in it.
		+
		+	We might be able to use this to prevent also adding any other function, essentially only allowing
		+
		+
		+	<syntaxhighlight lang="javascript">
		+	class MyToken extends MyParentTokenClass {}
		+
		+	</syntaxhighlight>
		+
		+
	<syntaxhighlight lang="javascript">		<syntaxhighlight lang="javascript">