Sneak peeks at a PHP library that simplifies the asynchronous code, just like `async` and `await` in ES7 Javascript.

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
difficult 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