Getting out of Callback Hell in PHP
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Sneak peeks at a PHP library that simplifies the asynchronous code, just like `async` and `await` in ES7 Javascript.
![CALLBACK
$web3 = new Web3('http://localhost:8545');
$eth = $web3->eth;
$eth->accounts(function ($err, $accounts) use ($eth) {
if ($err !== null) {
echo 'Error: ' . $err->getMessage();
return;
}
$eth->getBalance($accounts[0], function ($err, $balance) use ($eth, $accounts) {
if ($err !== null) {
echo 'Error: ' . $err->getMessage();
return;
}
echo $accounts[0] . ' Balance: ' . $balance . PHP_EOL;
$eth->getBalance($accounts[1], function ($err, $balance2) use ($eth, $accounts, $balance) {
if ($err !== null) {
echo 'Error: ' . $err->getMessage();
return;
}
echo $accounts[1] . ' Balance: ' . $balance2 . PHP_EOL;
$total = $balance->add($balance2);
echo 'Total Balance: ' . $total . PHP_EOL;
});
});
});](https://image.slidesharecdn.com/asyncawait-180706031723/85/Getting-out-of-Callback-Hell-in-PHP-8-320.jpg)
![<?php
require __DIR__ . '/../vendor/autoload.php';
use Web3Web3;
try {
$web3 = new Web3('http://localhost:8545');
$eth = $web3->eth;
$accounts = $eth->accounts();
$balance = $eth->getBalance($accounts[0]);
echo $accounts[0] . ' Balance: ' . $balance . PHP_EOL;
$balance2 = $eth->getBalance($accounts[1]);
echo $accounts[1] . ' Balance: ' . $balance2 . PHP_EOL;
$total = $balance->add($balance2);
echo 'Total Balance: ' . $total . PHP_EOL;
} catch (Throwable $err) {
echo 'Error: ' . $err->getMessage();
}
/*
0x262bc77dfc5748620641325b3617fc07b20f0b92 Balance: 100000000000000000000
0x2d8785375886cf900126cf3082aad6f47427a1d7 Balance: 100000000000000000000
Total Balance: 200000000000000000000
*/
SYNC](https://image.slidesharecdn.com/asyncawait-180706031723/85/Getting-out-of-Callback-Hell-in-PHP-9-320.jpg)
![SYNCuse Web3Web3;
function balance()
{
try {
$web3 = new Web3('http://localhost:8545');
$eth = $web3->eth;
$accounts = $eth->accounts();
$balance = $eth->getBalance($accounts[0]);
echo $accounts[0] . ' Balance: ' . $balance . PHP_EOL;
$balance2 = $eth->getBalance($accounts[1]);
echo $accounts[1] . ' Balance: ' . $balance2 . PHP_EOL;
$total = $balance->add($balance2);
echo 'Total Balance: ' . $total . PHP_EOL;
return $total;
} catch (Throwable $err) {
echo 'Error: ' . $err->getMessage();
}
}
balance();
/*
0x262bc77dfc5748620641325b3617fc07b20f0b92 Balance: 100000000000000000000
0x2d8785375886cf900126cf3082aad6f47427a1d7 Balance: 100000000000000000000
Total Balance: 200000000000000000000
*/](https://image.slidesharecdn.com/asyncawait-180706031723/85/Getting-out-of-Callback-Hell-in-PHP-10-320.jpg)
![use Web3Web3;
function balance(): Generator
{
try {
$web3 = new Web3('http://localhost:8545');
$eth = $web3->eth;
$accounts = yield [$eth, 'accounts'];
$balance = yield [$eth, 'getBalance', $accounts[0]];
echo $accounts[0] . ' Balance: ' . $balance . PHP_EOL;
$balance2 = yield [$eth, 'getBalance', $accounts[1]];
echo $accounts[1] . ' Balance: ' . $balance2 . PHP_EOL;
$total = $balance->add($balance2);
echo 'Total Balance: ' . $total . PHP_EOL;
return $total;
} catch (Throwable $err) {
echo 'Error: ' . $err->getMessage();
}
}
async(balance());
/*
0x262bc77dfc5748620641325b3617fc07b20f0b92 Balance: 100000000000000000000
0x2d8785375886cf900126cf3082aad6f47427a1d7 Balance: 100000000000000000000
Total Balance: 200000000000000000000
*/
ASYNC](https://image.slidesharecdn.com/asyncawait-180706031723/85/Getting-out-of-Callback-Hell-in-PHP-11-320.jpg)
![function balance(): Generator
{
try {
$web3 = new Web3('http://localhost:8545');
$eth = $web3->eth;
$accounts = yield [$eth, 'accounts'];
$total = new BigInteger();
foreach ($accounts as $account) {
$balance = yield [$eth, 'getBalance', $account];
echo $account . ' Balance: ' . $balance . PHP_EOL;
$total = $total->add($balance);
}
echo 'Total Balance: ' . $total . PHP_EOL;
return $total;
} catch (Throwable $err) {
echo 'Error: ' . $err->getMessage();
}
}
async(balance());
ASYNC](https://image.slidesharecdn.com/asyncawait-180706031723/85/Getting-out-of-Callback-Hell-in-PHP-13-320.jpg)
![Symfony internals [english]](https://cdn.slidesharecdn.com/ss_thumbnails/symfonyinternalsenglish-120615182511-phpapp01-thumbnail.jpg?width=560&fit=bounds)
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Getting out of Callback Hell in PHP
- 1. THE CALLBACK HELL a sneak peak! Getting out of
- 2. ¡°The situation where callbacks are nested within other callbacks several levels deep, potentially making it di?cult to understand and maintain the code. -Wiktionary
- 3. USE OF CALLBACKS Why just wait for Disk reading/writing Network reading/writing Communication with DB Sending mail When we have other things to do
- 4. USE OF CALLBACKS an example
- 5. WHY WE NEED CALLBACKS? Typically PHP JS
- 6. NOW PHP CAN DO ASYNC ? Several built-in functions ? Several libraries (using the built-in functions) ? Facebook Hack
- 7. NOW PHP CAN DO ASYNC ? Several built-in functions ? Using Curl as async system ? Several libraries (using the built-in functions) ? ReactPHP ? Facebook Hack
- 8. CALLBACK $web3 = new Web3('http://localhost:8545'); $eth = $web3->eth; $eth->accounts(function ($err, $accounts) use ($eth) { if ($err !== null) { echo 'Error: ' . $err->getMessage(); return; } $eth->getBalance($accounts[0], function ($err, $balance) use ($eth, $accounts) { if ($err !== null) { echo 'Error: ' . $err->getMessage(); return; } echo $accounts[0] . ' Balance: ' . $balance . PHP_EOL; $eth->getBalance($accounts[1], function ($err, $balance2) use ($eth, $accounts, $balance) { if ($err !== null) { echo 'Error: ' . $err->getMessage(); return; } echo $accounts[1] . ' Balance: ' . $balance2 . PHP_EOL; $total = $balance->add($balance2); echo 'Total Balance: ' . $total . PHP_EOL; }); }); });
- 9. <?php require __DIR__ . '/../vendor/autoload.php'; use Web3Web3; try { $web3 = new Web3('http://localhost:8545'); $eth = $web3->eth; $accounts = $eth->accounts(); $balance = $eth->getBalance($accounts[0]); echo $accounts[0] . ' Balance: ' . $balance . PHP_EOL; $balance2 = $eth->getBalance($accounts[1]); echo $accounts[1] . ' Balance: ' . $balance2 . PHP_EOL; $total = $balance->add($balance2); echo 'Total Balance: ' . $total . PHP_EOL; } catch (Throwable $err) { echo 'Error: ' . $err->getMessage(); } /* 0x262bc77dfc5748620641325b3617fc07b20f0b92 Balance: 100000000000000000000 0x2d8785375886cf900126cf3082aad6f47427a1d7 Balance: 100000000000000000000 Total Balance: 200000000000000000000 */ SYNC
- 10. SYNCuse Web3Web3; function balance() { try { $web3 = new Web3('http://localhost:8545'); $eth = $web3->eth; $accounts = $eth->accounts(); $balance = $eth->getBalance($accounts[0]); echo $accounts[0] . ' Balance: ' . $balance . PHP_EOL; $balance2 = $eth->getBalance($accounts[1]); echo $accounts[1] . ' Balance: ' . $balance2 . PHP_EOL; $total = $balance->add($balance2); echo 'Total Balance: ' . $total . PHP_EOL; return $total; } catch (Throwable $err) { echo 'Error: ' . $err->getMessage(); } } balance(); /* 0x262bc77dfc5748620641325b3617fc07b20f0b92 Balance: 100000000000000000000 0x2d8785375886cf900126cf3082aad6f47427a1d7 Balance: 100000000000000000000 Total Balance: 200000000000000000000 */
- 11. use Web3Web3; function balance(): Generator { try { $web3 = new Web3('http://localhost:8545'); $eth = $web3->eth; $accounts = yield [$eth, 'accounts']; $balance = yield [$eth, 'getBalance', $accounts[0]]; echo $accounts[0] . ' Balance: ' . $balance . PHP_EOL; $balance2 = yield [$eth, 'getBalance', $accounts[1]]; echo $accounts[1] . ' Balance: ' . $balance2 . PHP_EOL; $total = $balance->add($balance2); echo 'Total Balance: ' . $total . PHP_EOL; return $total; } catch (Throwable $err) { echo 'Error: ' . $err->getMessage(); } } async(balance()); /* 0x262bc77dfc5748620641325b3617fc07b20f0b92 Balance: 100000000000000000000 0x2d8785375886cf900126cf3082aad6f47427a1d7 Balance: 100000000000000000000 Total Balance: 200000000000000000000 */ ASYNC
- 12. function balance() { try { $web3 = new Web3('http://localhost:8545'); $eth = $web3->eth; $accounts = $eth->accounts(); $total = new BigInteger(); foreach ($accounts as $account) { $balance = $eth->getBalance($account); echo $accounts . ' Balance: ' . $balance . PHP_EOL; $total = $total->add($balance); } echo 'Total Balance: ' . $total . PHP_EOL; return $total; } catch (Throwable $err) { echo 'Error: ' . $err->getMessage(); } } balance(); SYNC
- 13. function balance(): Generator { try { $web3 = new Web3('http://localhost:8545'); $eth = $web3->eth; $accounts = yield [$eth, 'accounts']; $total = new BigInteger(); foreach ($accounts as $account) { $balance = yield [$eth, 'getBalance', $account]; echo $account . ' Balance: ' . $balance . PHP_EOL; $total = $total->add($balance); } echo 'Total Balance: ' . $total . PHP_EOL; return $total; } catch (Throwable $err) { echo 'Error: ' . $err->getMessage(); } } async(balance()); ASYNC