8000 Show implementation problems and renumber examples · HowProgrammingWorks/Transaction@4db9f6e · GitHub
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tshemsedinovtshemsedinov
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Show implementation problems and renumber examples
1 parent d108ebb commit 4db9f6e

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+87
-90
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3 files changed

+87
-90
lines changed

‎JavaScript/3-problems.js

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,62 @@
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'use strict';
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function Transaction() {}
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Transaction.start = (data) => {
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console.log('\nstart transaction');
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let delta = {};
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const methods = {
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commit: () => {
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console.log('\ncommit transaction');
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Object.assign(data, delta);
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delta = {};
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},
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rollback: () => {
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console.log('\nrollback transaction');
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delta = {};
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}
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};
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return new Proxy(data, {
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get(target, key) {
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if (methods.hasOwnProperty(key)) return methods[key];
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if (delta.hasOwnProperty(key)) return delta[key];
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return target[key];
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},
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set(target, key, val) {
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console.log('set', key, val);
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if (target[key] === val) delete delta[key];
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else delta[key] = val;
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return true;
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}
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});
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};
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// Usage
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const data = { name: 'Marcus Aurelius', born: 121 };
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const transaction = Transaction.start(data);
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console.log('data', JSON.stringify(data));
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console.log('transaction', JSON.stringify(transaction));
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transaction.name = 'Mao Zedong';
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transaction.born = 1893;
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transaction.city = 'Shaoshan';
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console.log('\noutput with JSON.stringify:');
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console.log('data', JSON.stringify(data));
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console.log('transaction', JSON.stringify(transaction));
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console.log('\noutput with console.dir:');
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console.dir({ transaction });
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console.log('\noutput with for-in:');
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for (const key in transaction) {
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console.log(key, transaction[key]);
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}
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transaction.commit();
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console.log('data', JSON.stringify(data));
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console.log('transaction', JSON.stringify(transaction));

‎JavaScript/4-delta.js

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This file was deleted.

‎JavaScript/3-descriptor.js renamed to ‎JavaScript/4-descriptor.js

Lines changed: 25 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -3,17 +3,17 @@
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function Transaction() {}
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Transaction.start = (data) => {
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console.log('start transaction');
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console.log('\nstart transaction');
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let delta = {};
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const methods = {
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commit: () => {
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console.log('commit transaction');
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console.log('\ncommit transaction');
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Object.assign(data, delta);
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delta = {};
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},
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rollback: () => {
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console.log('rollback transaction');
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console.log('\nrollback transaction');
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delta = {};
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}
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};
@@ -24,11 +24,14 @@ Transaction.start = (data) => {
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if (delta.hasOwnProperty(key)) return delta[key];
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return target[key];
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},
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// Added handler
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getOwnPropertyDescriptor: (target, key) => (
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Object.getOwnPropertyDescriptor(
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delta.hasOwnProperty(key) ? delta : target, key
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)
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),
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set(target, key, val) {
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console.log('set', key, val);
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if (target[key] === val) delete delta[key];
@@ -40,25 +43,30 @@ Transaction.start = (data) => {
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// Usage
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const data = { name: 'Marcus Aurelius', city: 'Rome', born: 121 };
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const data = { name: 'Marcus Aurelius', born: 121 };
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const transaction = Transaction.start(data);
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console.log(JSON.stringify(data), JSON.stringify(transaction));
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console.dir({ data, transaction });
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console.log('data', JSON.stringify(data));
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console.log('transaction', JSON.stringify(transaction));
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transaction.name = 'Mao Zedong';
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transaction.born = 1893;
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console.log('JSON:', JSON.stringify(data), JSON.stringify(transaction));
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console.dir({ data, transaction });
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transaction.city = 'Shaoshan';
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transaction.commit();
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console.log('JSON:', JSON.stringify(data), JSON.stringify(transaction));
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console.dir({ data, transaction });
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console.log('\noutput with JSON.stringify:');
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console.log('data', JSON.stringify(data));
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console.log('transaction *', JSON.stringify(transaction));
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transaction.city = 'Shaoshan';
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console.log('JSON:', JSON.stringify(data), JSON.stringify(transaction));
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console.dir({ data, transaction });
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console.log('\noutput with console.dir *:');
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console.dir({ transaction });
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console.log('\noutput with for-in *:');
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for (const key in transaction) {
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console.log(key, transaction[key]);
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}
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transaction.rollback();
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console.log('JSON:', JSON.stringify(data), JSON.stringify(transaction));
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console.dir({ data, transaction });
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console.log('\n* partially fixed, except .city\n');
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transaction.commit();
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console.log('data', JSON.stringify(data));
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console.log('transaction', JSON.stringify(transaction));

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