Oops: corrected the typo in the example!
class MyClass {
data = {};
constructor() {
return new Proxy(this, {
get(target, prop) {
prop = prop.toString();
console.log(`Getting property: ${prop}`);
if(prop==="toString"){
return target.toString.bind(target);
}
if(prop==='valueOf'){
return target.valueOf.bind(target);
}
if(prop==="Symbol(Symbol.iterator)"){
return target[Symbol.iterator].bind(target);
}
return target.data[prop];
},
set(target, prop, value) {
console.log(`Setting property: ${prop.toString()} to ${value}`);
target.data[prop] = value;
return true;
},
deleteProperty(target, prop) {
console.log(`Deleting property: ${prop.toString()}`);
delete target.data[prop.toString()];
return true;
},
has(target, prop) {
console.log(`Checking property presence: ${prop.toString()}`);
return prop in target.data;
},
});
}
valueOf() {
return 'running valueOf: ' + JSON.stringify(this.data);
}
toString() {
return 'running tostring:' + JSON.stringify(this.data);
}
*[Symbol.iterator]() {
for (const key in this.data) {
console.log('called iterator!');
yield [key, this.data[key]];
}
}
}
const obj = new MyClass();
obj['key'] = 'value'; // Setting property: key to value
console.log("testing setting and getting 'key'");
console.log(obj['key']); // Getting property: key, value
delete obj['key']; // Deleting property: key
console.log("deleted, should be false: ")
console.log('key' in obj); // Checking property presence: key, false
console.log("testing toString ")
obj['key3'] = 'value1';
obj['key4'] = 'value2';
console.log(obj.toString()); // {"key1":"value1","key2":"value2"}
console.log("testing Symbol.iterator");
for (const [key, value] of obj) {
console.log(`${key}: ${value}`);
}
On Friday, August 4, 2023 at 9:53:24 PM UTC-4 Félix wrote:
> Dunder methods being (unexhaustive list) : *__contains__, __delitem__,
> __getitem__, __setitem__, __iter__ and __repr__* in my case.
>
> Using javascript little-known 'Proxy object', and passing itself as the
> target, it's possible to implement the equivalent of Leo's
> SqlitePickleShare class!
>
> *simple proof-of-concept below where it just mimics a dummy dict.
> Customize as needed for other behaviors!*
>
> Félix 🚀😊
>
> class MyClass {
> data = {};
>
> constructor() {
> return new Proxy(this, {
> get(target, prop) {
> prop = prop.toString();
> console.log(`Getting property: ${prop}`);
> if(prop==="toString"){
> return target.toString.bind(target);
> }
> if(prop==='valueOf'){
> return target.toString.bind(target);
> }
> if(prop==="Symbol(Symbol.iterator)"){
> return target[Symbol.iterator].bind(target);
> }
> return target.data[prop];
> },
> set(target, prop, value) {
> console.log(`Setting property: ${prop.toString()} to ${value}`);
> target.data[prop] = value;
> return true;
> },
> deleteProperty(target, prop) {
> console.log(`Deleting property: ${prop.toString()}`);
> delete target.data[prop.toString()];
> return true;
> },
> has(target, prop) {
> console.log(`Checking property presence: ${prop.toString()}`);
> return prop in target.data;
> },
> });
> }
>
> valueOf() {
> return 'running valueOf: ' + JSON.stringify(this.data);
> }
> toString() {
> return 'running tostring:' + JSON.stringify(this.data);
> }
>
> *[Symbol.iterator]() {
> for (const key in this.data) {
> console.log('called iterator!');
> yield [key, this.data[key]];
> }
> }
>
> }
>
> const obj = new MyClass();
> obj['key'] = 'value'; // Setting property: key to value
> console.log("testing setting and getting 'key'");
> console.log(obj['key']); // Getting property: key, value
> delete obj['key']; // Deleting property: key
> console.log("deleted, should be false: ")
> console.log('key' in obj); // Checking property presence: key, false
>
> console.log("testing toString ")
> obj['key3'] = 'value1';
> obj['key4'] = 'value2';
> console.log(obj.toString()); // {"key1":"value1","key2":"value2"}
>
> console.log("testing Symbol.iterator");
> for (const [key, value] of obj) {
> console.log(`${key}: ${value}`);
> }
>
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