More on Personal Growth

Hudson Rennie
3 years ago
My Work at a $1.2 Billion Startup That Failed
Sometimes doing everything correctly isn't enough.
In 2020, I could fix my life.
After failing to start a business, I owed $40,000 and had no work.
A $1.2 billion startup on the cusp of going public pulled me up.
Ironically, it was getting ready for an epic fall — with the world watching.
Life sometimes helps. Without a base, even the strongest fall. A corporation that did everything right failed 3 months after going public.
First-row view.
Apple is the creator of Adore.
Out of respect, I've altered the company and employees' names in this account, despite their failure.
Although being a publicly traded company, it may become obvious.
We’ll call it “Adore” — a revolutionary concept in retail shopping.
Two Apple execs established Adore in 2014 with a focus on people-first purchasing.
Jon and Tim:
The concept for the stylish Apple retail locations you see today was developed by retail expert Jon Swanson, who collaborated closely with Steve Jobs.
Tim Cruiter is a graphic designer who produced the recognizable bouncing lamp video that appears at the start of every Pixar film.
The dynamic duo realized their vision.
“What if you could combine the convenience of online shopping with the confidence of the conventional brick-and-mortar store experience.”
Adore's mobile store concept combined traditional retail with online shopping.
Adore brought joy to 70+ cities and 4 countries over 7 years, including the US, Canada, and the UK.
Being employed on the ground floor, with world dominance and IPO on the horizon, was exciting.
I started as an Adore Expert.
I delivered cell phones, helped consumers set them up, and sold add-ons.
As the company grew, I became a Virtual Learning Facilitator and trained new employees across North America using Zoom.
In this capacity, I gained corporate insider knowledge. I worked with the creative team and Jon and Tim.
It's where I saw company foundation fissures. Despite appearances, investors were concerned.
The business strategy was ground-breaking.
Even after seeing my employee stocks fall from a home down payment to $0 (when Adore filed for bankruptcy), it's hard to pinpoint what went wrong.
Solid business model, well-executed.
Jon and Tim's chase for public funding ended in glory.
Here’s the business model in a nutshell:
Buying cell phones is cumbersome. You have two choices:
Online purchase: not knowing what plan you require or how to operate your device.
Enter a store, which can be troublesome and stressful.
Apple, AT&T, and Rogers offered Adore as a free delivery add-on. Customers could:
Have their phone delivered by UPS or Canada Post in 1-2 weeks.
Alternately, arrange for a person to visit them the same day (or sometimes even the same hour) to assist them set up their phone and demonstrate how to use it (transferring contacts, switching the SIM card, etc.).
Each Adore Expert brought a van with extra devices and accessories to customers.
Happy customers.
Here’s how Adore and its partners made money:
Adores partners appreciated sending Experts to consumers' homes since they improved customer satisfaction, average sale, and gadget returns.
**Telecom enterprises have low customer satisfaction. The average NPS is 30/100. Adore's global NPS was 80.
Adore made money by:
a set cost for each delivery
commission on sold warranties and extras
Consumer product applications seemed infinite.
A proprietary scheduling system (“The Adore App”), allowed for same-day, even same-hour deliveries.
It differentiates Adore.
They treated staff generously by:
Options on stock
health advantages
sales enticements
high rates per hour
Four-day workweeks were set by experts.
Being hired early felt like joining Uber, Netflix, or Tesla. We hoped the company's stocks would rise.
Exciting times.
I smiled as I greeted more than 1,000 new staff.
I spent a decade in retail before joining Adore. I needed a change.
After a leap of faith, I needed a lifeline. So, I applied for retail sales jobs in the spring of 2019.
The universe typically offers you what you want after you accept what you need. I needed a job to settle my debt and reach $0 again.
And the universe listened.
After being hired as an Adore Expert, I became a Virtual Learning Facilitator. Enough said.
After weeks of economic damage from the pandemic.
This employment let me work from home during the pandemic. It taught me excellent business skills.
I was active in brainstorming, onboarding new personnel, and expanding communication as we grew.
This job gave me vital skills and a regular paycheck during the pandemic.
It wasn’t until January of 2022 that I left on my own accord to try to work for myself again — this time, it’s going much better.
Adore was perfect. We valued:
Connection
Discovery
Empathy
Everything we did centered on compassion, and we held frequent Justice Calls to discuss diversity and work culture.
The last day of onboarding typically ended in tears as employees felt like they'd found a home, as I had.
Like all nice things, the wonderful vibes ended.
First indication of distress
My first day at the workplace was great.
Fun, intuitive, and they wanted creative individuals, not salesman.
While sales were important, the company's vision was more important.
“To deliver joy through life-changing mobile retail experiences.”
Thorough, forward-thinking training. We had a module on intuition. It gave us role ownership.
We were flown cross-country for training, gave feedback, and felt like we made a difference. Multiple contacts responded immediately and enthusiastically.
The atmosphere was genuine.
Making money was secondary, though. Incredible service was a priority.
Jon and Tim answered new hires' questions during Zoom calls during onboarding. CEOs seldom meet new hires this way, but they seemed to enjoy it.
All appeared well.
But in late 2021, things started changing.
Adore's leadership changed after its IPO. From basic values to sales maximization. We lost communication and were forced to fend for ourselves.
Removed the training wheels.
It got tougher to gain instructions from those above me, and new employees told me their roles weren't as advertised.
External money-focused managers were hired.
Instead of creative types, we hired salespeople.
With a new focus on numbers, Adore's uniqueness began to crumble.
Via Zoom, hundreds of workers were let go.
So.
Early in 2022, mass Zoom firings were trending. A CEO firing 900 workers over Zoom went viral.
Adore was special to me, but it became a headline.
30 June 2022, Vice Motherboard published Watch as Adore's CEO Fires Hundreds.
It described a leaked video of Jon Swanson laying off all staff in Canada and the UK.
They called it a “notice of redundancy”.
The corporation couldn't pay its employees.
I loved Adore's underlying ideals, among other things. We called clients Adorers and sold solutions, not add-ons.
But, like anything, a company is only as strong as its weakest link. And obviously, the people-first focus wasn’t making enough money.
There were signs. The expansion was presumably a race against time and money.
Adore finally declared bankruptcy.
Adore declared bankruptcy 3 months after going public. It happened in waves, like any large-scale fall.
Initial key players to leave were
Then, communication deteriorated.
Lastly, the corporate culture disintegrated.
6 months after leaving Adore, I received a letter in the mail from a Law firm — it was about my stocks.
Adore filed Chapter 11. I had to sue to collect my worthless investments.
I hoped those stocks will be valuable someday. Nope. Nope.
Sad, I sighed.
$1.2 billion firm gone.
I left the workplace 3 months before starting a writing business. Despite being mediocre, I'm doing fine.
I got up as Adore fell.
Finally, can we scale kindness?
I trust my gut. Changes at Adore made me leave before it sank.
Adores' unceremonious slide from a top startup to bankruptcy is astonishing to me.
The company did everything perfectly, in my opinion.
first to market,
provided excellent service
paid their staff handsomely.
was responsible and attentive to criticism
The company wasn't led by an egotistical eccentric. The crew had centuries of cumulative space experience.
I'm optimistic about the future of work culture, but is compassion scalable?

Aparna Jain
3 years ago
Negative Effects of Working for a FAANG Company
Consider yourself lucky if your last FAANG interview was rejected.
FAANG—Facebook, Apple, Amazon, Netflix, Google
(I know its manga now, but watch me not care)
These big companies offer many benefits.
large salaries and benefits
Prestige
high expectations for both you and your coworkers.
However, these jobs may have major drawbacks that only become apparent when you're thrown to the wolves, so it's up to you whether you see them as drawbacks or opportunities.
I know most college graduates start working at big tech companies because of their perceived coolness.
I've worked in these companies for years and can tell you what to expect if you get a job here.
Little fish in a vast ocean
The most obvious. Most billion/trillion-dollar companies employ thousands.
You may work on a small, unnoticed product part.
Directors and higher will sometimes make you redo projects they didn't communicate well without respecting your time, talent, or will to work on trivial stuff that doesn't move company needles.
Peers will only say, "Someone has to take out the trash," even though you know company resources are being wasted.
The power imbalance is frustrating.
What you can do about it
Know your WHY. Consider long-term priorities. Though riskier, I stayed in customer-facing teams because I loved building user-facing products.
This increased my impact. However, if you enjoy helping coworkers build products, you may be better suited for an internal team.
I told the Directors and Vice Presidents that their actions could waste Engineering time, even though it was unpopular. Some were receptive, some not.
I kept having tough conversations because they were good for me and the company.
However, some of my coworkers praised my candor but said they'd rather follow the boss.
An outdated piece of technology can take years to update.
Apple introduced Swift for iOS development in 2014. Most large tech companies adopted the new language after five years.
This is frustrating if you want to learn new skills and increase your market value.
Knowing that my lack of Swift practice could hurt me if I changed jobs made writing verbose Objective C painful.
What you can do about it
Work on the new technology in side projects; one engineer rewrote the Lyft app in Swift over the course of a weekend and promoted its adoption throughout the entire organization.
To integrate new technologies and determine how to combine legacy and modern code, suggest minor changes to the existing codebase.
Most managers spend their entire day in consecutive meetings.
After their last meeting, the last thing they want is another meeting to discuss your career goals.
Sometimes a manager has 15-20 reports, making it hard to communicate your impact.
Misunderstandings and stress can result.
Especially when the manager should focus on selfish parts of the team. Success won't concern them.
What you can do about it
Tell your manager that you are a self-starter and that you will pro-actively update them on your progress, especially if they aren't present at the meetings you regularly attend.
Keep being proactive and look for mentorship elsewhere if you believe your boss doesn't have enough time to work on your career goals.
Alternately, look for a team where the manager has more authority to assist you in making career decisions.
After a certain point, company loyalty can become quite harmful.
Because big tech companies create brand loyalty, too many colleagues stayed in unhealthy environments.
When you work for a well-known company and strangers compliment you, it's fun to tell your friends.
Work defines you. This can make you stay too long even though your career isn't progressing and you're unhappy.
Google may become your surname.
Workplaces are not families.
If you're unhappy, don't stay just because they gave you the paycheck to buy your first home and make you feel like you owe your life to them.
Many employees stayed too long. Though depressed and suicidal.
What you can do about it
Your life is not worth a company.
Do you want your job title and workplace to be listed on your gravestone? If not, leave if conditions deteriorate.
Recognize that change can be challenging. It's difficult to leave a job you've held for a number of years.
Ask those who have experienced this change how they handled it.
You still have a bright future if you were rejected from FAANG interviews.
Rejections only lead to amazing opportunities. If you're young and childless, work for a startup.
Companies may pay more than FAANGs. Do your research.
Ask recruiters and hiring managers tough questions about how the company and teams prioritize respectful working hours and boundaries for workers.
I know many 15-year-olds who have a lifelong dream of working at Google, and it saddens me that they're chasing a name on their resume instead of excellence.
This article is not meant to discourage you from working at these companies, but to share my experience about what HR/managers will never mention in interviews.
Read both sides before signing the big offer letter.

Neeramitra Reddy
3 years ago
The best life advice I've ever heard could very well come from 50 Cent.
He built a $40M hip-hop empire from street drug dealing.
50 Cent was nearly killed by 9mm bullets.
Before 50 Cent, Curtis Jackson sold drugs.
He sold coke to worried addicts after being orphaned at 8.
Pursuing police. Murderous hustlers and gangs. Unwitting informers.
Despite his hard life, his hip-hop career was a success.
An assassination attempt ended his career at the start.
What sane producer would want to deal with a man entrenched in crime?
Most would have drowned in self-pity and drank themselves to death.
But 50 Cent isn't most people. Life on the streets had given him fearlessness.
“Having a brush with death, or being reminded in a dramatic way of the shortness of our lives, can have a positive, therapeutic effect. So it is best to make every moment count, to have a sense of urgency about life.” ― 50 Cent, The 50th Law
50 released a series of mixtapes that caught Eminem's attention and earned him a $50 million deal!
50 Cents turned death into life.
Things happen; that is life.
We want problems solved.
Every human has problems, whether it's Jeff Bezos swimming in his billions, Obama in his comfortable retirement home, or Dan Bilzerian with his hired bikini models.
All problems.
Problems churn through life. solve one, another appears.
It's harsh. Life's unfair. We can face reality or run from it.
The latter will worsen your issues.
“The firmer your grasp on reality, the more power you will have to alter it for your purposes.” — 50 Cent, The 50th Law
In a fantasy-obsessed world, 50 Cent loves reality.
Wish for better problem-solving skills rather than problem-free living.
Don't wish, work.
We All Have the True Power of Alchemy
Humans are arrogant enough to think the universe cares about them.
That things happen as if the universe notices our nanosecond existences.
Things simply happen. Period.
By changing our perspective, we can turn good things bad.
The alchemists' search for the philosopher's stone may have symbolized the ability to turn our lead-like perceptions into gold.
Negativity bias tints our perceptions.
Normal sparring broke your elbow? Rest and rethink your training. Fired? You can improve your skills and get a better job.
Consider Curtis if he had fallen into despair.
The legend we call 50 Cent wouldn’t have existed.
The Best Lesson in Life Ever?
Neither avoid nor fear your reality.
That simple sentence contains every self-help tip and life lesson on Earth.
When reality is all there is, why fear it? avoidance?
Or worse, fleeing?
To accept reality, we must eliminate the words should be, could be, wish it were, and hope it will be.
It is. Period.
Only by accepting reality's chaos can you shape your life.
“Behind me is infinite power. Before me is endless possibility, around me is boundless opportunity. My strength is mental, physical and spiritual.” — 50 Cent
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Andy Raskin
3 years ago
I've Never Seen a Sales Deck This Good
It’s Zuora’s, and it’s brilliant. Here’s why.
My friend Tim got a sales position at a Series-C software company that garnered $60 million from A-list investors. He's one of the best salespeople I know, yet he emailed me after starting to struggle.
Tim has a few modest clients. “Big companies ignore my pitch”. Tim said.
I love helping teams write the strategic story that drives sales, marketing, and fundraising. Tim and I had lunch at Amber India on Market Street to evaluate his deck.
After a feast, I asked Tim when prospects tune out.
He said, “several slides in”.
Intent on maximizing dining ROI, Tim went back to the buffet for seconds. When he returned, I pulled out my laptop and launched into a Powerpoint presentation.
“What’s this?” Tim asked.
“This,” I said, “is the greatest sales deck I have ever seen.”
Five Essentials of a Great Sales Narrative
I showed Tim a sales slide from IPO-bound Zuora, which sells a SaaS platform for subscription billing. Zuora supports recurring payments (e.g. enterprise software).
Ex-Zuora salesman gave me the deck, saying it helped him close his largest business. (I don't know anyone who works at Zuora.) After reading this, a few Zuora employees contacted me.)
Tim abandoned his naan in a pool of goat curry and took notes while we discussed the Zuora deck.
We remarked how well the deck led prospects through five elements:
(The ex-Zuora salesperson begged me not to release the Zuora deck publicly.) All of the images below originate from Zuora's website and SlideShare channel.)
#1. Name a Significant Change in the World
Don't start a sales presentation with mentioning your product, headquarters, investors, clients, or yourself.
Name the world shift that raises enormous stakes and urgency for your prospect.
Every Zuora sales deck begins with this slide:
Zuora coined the term subscription economy to describe a new market where purchasers prefer regular service payments over outright purchases. Zuora then shows a slide with the change's history.
Most pitch recommendation advises starting with the problem. When you claim a problem, you put prospects on the defensive. They may be unaware of or uncomfortable admitting the situation.
When you highlight a global trend, prospects open up about how it affects them, worries them, and where they see opportunity. You capture their interest. Robert McKee says:
…what attracts human attention is change. …if the temperature around you changes, if the phone rings — that gets your attention. The way in which a story begins is a starting event that creates a moment of change.
#2. Show There’ll Be Winners and Losers
Loss aversion affects all prospects. They avoid a loss by sticking with the status quo rather than risking a gain by changing.
To fight loss aversion, show how the change will create winners and losers. You must show both
that if the prospect can adjust to the modification you mentioned, the outcome will probably be quite favorable; and
That failing to do so is likely to have an unacceptable negative impact on the prospect's future
Zuora shows a mass extinction among Fortune 500 firms.
…and then showing how the “winners” have shifted from product ownership to subscription services. Those include upstarts…
…as well as rejuvenated incumbents:
To illustrate, Zuora asks:
Winners utilize Zuora's subscription service models.
#3. Tease the Promised Land
It's tempting to get into product or service details now. Resist that urge.
Prospects won't understand why product/service details are crucial if you introduce them too soon, therefore they'll tune out.
Instead, providing a teaser image of the happily-ever-after your product/service will assist the prospect reach.
Your Promised Land should be appealing and hard to achieve without support. Otherwise, why does your company exist?
Zuora shows this Promised Land slide after explaining that the subscription economy will have winners and losers.
Not your product or service, but a new future state.
(I asked my friend Tim to describe his Promised Land, and he answered, "You’ll have the most innovative platform for ____." Nope: the Promised Land isn't possessing your technology, but living with it.)
Your Promised Land helps prospects market your solution to coworkers after your sales meeting. Your coworkers will wonder what you do without you. Your prospects are more likely to provide a persuasive answer with a captivating Promised Land.
#4. Present Features as “Mystic Gifts” for Overcoming Difficulties on the Road to the Promised Land
Successful sales decks follow the same format as epic films and fairy tales. Obi Wan gives Luke a lightsaber to help him destroy the Empire. You're Gandalf, helping Frodo destroy the ring. Your prospect is Cinderella, and you're her fairy godmother.
Position your product or service's skills as mystical gifts to aid your main character (prospect) achieve the Promised Land.
Zuora's client record slide is shown above. Without context, even the most technical prospect would be bored.
Positioned in the context of shifting from an “old” to a “new world”, it's the foundation for a compelling conversation with prospects—technical and otherwise—about why traditional solutions can't reach the Promised Land.
#5. Show Proof That You Can Make the Story True.
In this sense, you're promising possibilities that if they follow you, they'll reach the Promised Land.
The journey to the Promised Land is by definition rocky, so prospects are right to be cautious. The final part of the pitch is proof that you can make the story come true.
The most convincing proof is a success story about how you assisted someone comparable to the prospect. Zuora's sales people use a deck of customer success stories, but this one gets the essence.
I particularly appreciate this one from an NCR exec (a Zuora customer), which relates more strongly to Zuora's Promised Land:
Not enough successful customers? Product demos are the next best evidence, but features should always be presented in the context of helping a prospect achieve the Promised Land.
The best sales narrative is one that is told by everyone.
Success rarely comes from a fantastic deck alone. To be effective, salespeople need an organization-wide story about change, Promised Land, and Magic Gifts.
Zuora exemplifies this. If you hear a Zuora executive, including CEO Tien Tzuo, talk, you'll likely hear about the subscription economy and its winners and losers. This is the theme of the company's marketing communications, campaigns, and vision statement.
According to the ex-Zuora salesperson, company-wide story alignment made him successful.
The Zuora marketing folks ran campaigns and branding around this shift to the subscription economy, and [CEO] Tien [Tzuo] talked it up all the time. All of that was like air cover for my in-person sales ground attack. By the time I arrived, prospects were already convinced they had to act. It was the closest thing I’ve ever experienced to sales nirvana.
The largest deal ever
Tim contacted me three weeks after our lunch to tell me that prospects at large organizations were responding well to his new deck, which we modeled on Zuora's framework. First, prospects revealed their obstacles more quickly. The new pitch engages CFOs and other top gatekeepers better, he said.
A week later, Tim emailed that he'd signed his company's biggest agreement.
Next week, we’re headed back to Amber India to celebrate.

Juxtathinka
3 years ago
Why Is Blockchain So Popular?
What is Bitcoin?
The blockchain is a shared, immutable ledger that helps businesses record transactions and track assets. The blockchain can track tangible assets like cars, houses, and land. Tangible assets like intellectual property can also be tracked on the blockchain.
Imagine a blockchain as a distributed database split among computer nodes. A blockchain stores data in blocks. When a block is full, it is closed and linked to the next. As a result, all subsequent information is compiled into a new block that will be added to the chain once it is filled.
The blockchain is designed so that adding a transaction requires consensus. That means a majority of network nodes must approve a transaction. No single authority can control transactions on the blockchain. The network nodes use cryptographic keys and passwords to validate each other's transactions.
Blockchain History
The blockchain was not as popular in 1991 when Stuart Haber and W. Scott Stornetta worked on it. The blocks were designed to prevent tampering with document timestamps. Stuart Haber and W. Scott Stornetta improved their work in 1992 by using Merkle trees to increase efficiency and collect more documents on a single block.
In 2004, he developed Reusable Proof of Work. This system allows users to verify token transfers in real time. Satoshi Nakamoto invented distributed blockchains in 2008. He improved the blockchain design so that new blocks could be added to the chain without being signed by trusted parties.
Satoshi Nakomoto mined the first Bitcoin block in 2009, earning 50 Bitcoins. Then, in 2013, Vitalik Buterin stated that Bitcoin needed a scripting language for building decentralized applications. He then created Ethereum, a new blockchain-based platform for decentralized apps. Since the Ethereum launch in 2015, different blockchain platforms have been launched: from Hyperledger by Linux Foundation, EOS.IO by block.one, IOTA, NEO and Monero dash blockchain. The block chain industry is still growing, and so are the businesses built on them.
Blockchain Components
The Blockchain is made up of many parts:
1. Node: The node is split into two parts: full and partial. The full node has the authority to validate, accept, or reject any transaction. Partial nodes or lightweight nodes only keep the transaction's hash value. It doesn't keep a full copy of the blockchain, so it has limited storage and processing power.
2. Ledger: A public database of information. A ledger can be public, decentralized, or distributed. Anyone on the blockchain can access the public ledger and add data to it. It allows each node to participate in every transaction. The distributed ledger copies the database to all nodes. A group of nodes can verify transactions or add data blocks to the blockchain.
3. Wallet: A blockchain wallet allows users to send, receive, store, and exchange digital assets, as well as monitor and manage their value. Wallets come in two flavors: hardware and software. Online or offline wallets exist. Online or hot wallets are used when online. Without an internet connection, offline wallets like paper and hardware wallets can store private keys and sign transactions. Wallets generally secure transactions with a private key and wallet address.
4. Nonce: A nonce is a short term for a "number used once''. It describes a unique random number. Nonces are frequently generated to modify cryptographic results. A nonce is a number that changes over time and is used to prevent value reuse. To prevent document reproduction, it can be a timestamp. A cryptographic hash function can also use it to vary input. Nonces can be used for authentication, hashing, or even electronic signatures.
5. Hash: A hash is a mathematical function that converts inputs of arbitrary length to outputs of fixed length. That is, regardless of file size, the hash will remain unique. A hash cannot generate input from hashed output, but it can identify a file. Hashes can be used to verify message integrity and authenticate data. Cryptographic hash functions add security to standard hash functions, making it difficult to decipher message contents or track senders.
Blockchain: Pros and Cons
The blockchain provides a trustworthy, secure, and trackable platform for business transactions quickly and affordably. The blockchain reduces paperwork, documentation errors, and the need for third parties to verify transactions.
Blockchain security relies on a system of unaltered transaction records with end-to-end encryption, reducing fraud and unauthorized activity. The blockchain also helps verify the authenticity of items like farm food, medicines, and even employee certification. The ability to control data gives users a level of privacy that no other platform can match.
In the case of Bitcoin, the blockchain can only handle seven transactions per second. Unlike Hyperledger and Visa, which can handle ten thousand transactions per second. Also, each participant node must verify and approve transactions, slowing down exchanges and limiting scalability.
The blockchain requires a lot of energy to run. In addition, the blockchain is not a hugely distributable system and it is destructible. The security of the block chain can be compromised by hackers; it is not completely foolproof. Also, since blockchain entries are immutable, data cannot be removed. The blockchain's high energy consumption and limited scalability reduce its efficiency.
Why Is Blockchain So Popular?
The blockchain is a technology giant. In 2018, 90% of US and European banks began exploring blockchain's potential. In 2021, 24% of companies are expected to invest $5 million to $10 million in blockchain. By the end of 2024, it is expected that corporations will spend $20 billion annually on blockchain technical services.
Blockchain is used in cryptocurrency, medical records storage, identity verification, election voting, security, agriculture, business, and many other fields. The blockchain offers a more secure, decentralized, and less corrupt system of making global payments, which cryptocurrency enthusiasts love. Users who want to save time and energy prefer it because it is faster and less bureaucratic than banking and healthcare systems.
Most organizations have jumped on the blockchain bandwagon, and for good reason: the blockchain industry has never had more potential. The launch of IBM's Blockchain Wire, Paystack, Aza Finance and Bloom are visible proof of the wonders that the blockchain has done. The blockchain's cryptocurrency segment may not be as popular in the future as the blockchain's other segments, as evidenced by the various industries where it is used. The blockchain is here to stay, and it will be discussed for a long time, not just in tech, but in many industries.
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mbvissers.eth
3 years ago
Why does every smart contract seem to implement ERC165?
ERC165 (or EIP-165) is a standard utilized by various open-source smart contracts like Open Zeppelin or Aavegotchi.
What's it? You must implement? Why do we need it? I'll describe the standard and answer any queries.
What is ERC165
ERC165 detects and publishes smart contract interfaces. Meaning? It standardizes how interfaces are recognized, how to detect if they implement ERC165, and how a contract publishes the interfaces it implements. How does it work?
Why use ERC165? Sometimes it's useful to know which interfaces a contract implements, and which version.
Identifying interfaces
An interface function's selector. This verifies an ABI function. XORing all function selectors defines an interface in this standard. The following code demonstrates.
// SPDX-License-Identifier: UNLICENCED
pragma solidity >=0.8.0 <0.9.0;
interface Solidity101 {
function hello() external pure;
function world(int) external pure;
}
contract Selector {
function calculateSelector() public pure returns (bytes4) {
Solidity101 i;
return i.hello.selector ^ i.world.selector;
// Returns 0xc6be8b58
}
function getHelloSelector() public pure returns (bytes4) {
Solidity101 i;
return i.hello.selector;
// Returns 0x19ff1d21
}
function getWorldSelector() public pure returns (bytes4) {
Solidity101 i;
return i.world.selector;
// Returns 0xdf419679
}
}This code isn't necessary to understand function selectors and how an interface's selector can be determined from the functions it implements.
Run that sample in Remix to see how interface function modifications affect contract function output.
Contracts publish their implemented interfaces.
We can identify interfaces. Now we must disclose the interfaces we're implementing. First, import IERC165 like so.
pragma solidity ^0.4.20;
interface ERC165 {
/// @notice Query if a contract implements an interface
/// @param interfaceID The interface identifier, as specified in ERC-165
/// @dev Interface identification is specified in ERC-165.
/// @return `true` if the contract implements `interfaceID` and
/// `interfaceID` is not 0xffffffff, `false` otherwise
function supportsInterface(bytes4 interfaceID) external view returns (bool);
}We still need to build this interface in our smart contract. ERC721 from OpenZeppelin is a good example.
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/ERC721.sol)
pragma solidity ^0.8.0;
import "./IERC721.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/introspection/ERC165.sol";
// ...
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
// ...
function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
return
interfaceId == type(IERC721).interfaceId ||
interfaceId == type(IERC721Metadata).interfaceId ||
super.supportsInterface(interfaceId);
}
// ...
}I deleted unnecessary code. The smart contract imports ERC165, IERC721 and IERC721Metadata. The is keyword at smart contract declaration implements all three.
Kind (interface).
Note that type(interface).interfaceId returns the same as the interface selector.
We override supportsInterface in the smart contract to return a boolean that checks if interfaceId is the same as one of the implemented contracts.
Super.supportsInterface() calls ERC165 code. Checks if interfaceId is IERC165.
function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
return interfaceId == type(IERC165).interfaceId;
}So, if we run supportsInterface with an interfaceId, our contract function returns true if it's implemented and false otherwise. True for IERC721, IERC721Metadata, andIERC165.
Conclusion
I hope this post has helped you understand and use ERC165 and why it's employed.
Have a great day, thanks for reading!
