#
Migration: From Ethers v4

##
BigNumber

###
Namespace

Since BigNumber is used quite frequently, it has been moved to the top level of the umbrella package.

// v4
ethers.utils.BigNumber
ethers.utils.BigNumberish
// v5
ethers.BigNumber
ethers.BigNumberish

###
Creating Instances

The `bigNumberify` method was always preferred over the constructor since it could short-circuit an object instantiation for [[bignumber] objects (since they are immutable). This has been moved to a static `from` class method.

// v4
new ethers.utils.BigNumber(someValue)
ethers.utils.bigNumberify(someValue);
// v5
// - Constructor is private
// - Removed `bigNumberify`
ethers.BigNumber.from(someValue)

##
Contracts

TODO

##
Errors

###
Namespace

All errors now belong to the Logger class and the related functions have been moved to Logger instances, which can include a per-package version string.

Global error fucntions have been moved Logger class methods.

// v4
ethers.errors.UNKNOWN_ERROR
ethers.errors.*
errors.setCensorship(censorship, permanent)
errors.setLogLevel(logLevel)
errors.checkArgumentCount(count, expectedCount, suffix)
errors.checkNew(self, kind)
errors.checkNormalize()
errors.throwError(message, code, params)
errors.warn(...)
errors.info(...)
// v5
ethers.utils.Logger.errors.UNKNOWN_ERROR
ethers.utils.Logger.errors.*
Logger.setCensorship(censorship, permanent)
Logger.setLogLevel(logLevel)
const logger = new ethers.utils.Logger(version);
logger.checkArgumentCount(count, expectedCount, suffix)
logger.checkNew(self, kind)
logger.checkNormalize()
logger.throwError(message, code, params)
logger.warn(...)
logger.info(...)

##
Interface

The Interface object has undergone the most dramatic changes.

It is no longer a meta-class and now has methods that simplify handling contract interface operations without the need for object inspection and special edge cases.

###
Functions

// v4 (example: "transfer(address to, uint amount)")
interface.functions.transfer.encode(to, amount)
interface.functions.transfer.decode(callData)
// v5
interface.encodeData("transfer", [ to, amount ])
interface.decodeResult("transfer", data)
// Or you can use any compatible signature or Fragment objects.
// Notice that signature normalization is performed for you,
// e.g. "uint" and "uint256" will be automatically converted
interface.encodeData("transfer(address,uint)", [ to, amount ])
interface.decodeResult("transfer(address to, uint256 amount)", data)

###
Events

// v4 (example: Transfer(address indexed, address indexed, uint256)
interface.events.Transfer.encodeTopics(values)
interface.events.Transfer.decode(data, topics)
// v5
interface.encodeFilterTopics("Transfer", values)
interface.encodeEventLog("Transfer", data, topics)

###
Inspection

Interrogating properties about a function or event can now (mostly) be done directly on the Fragment object.

// v4
interface.functions.transfer.name
interface.functions.transfer.inputs
interface.functions.transfer.outputs
interface.functions.transfer.payable
interface.functions.transfer.gas
// v5
const functionFragment = interface.getFunction("transfer")
functionFragment.name
functionFragment.inputs
functionFragment.outputs
functionFragment.payable
functionFragment.gas
// v4; type is "call" or "transaction"
interface.functions.transfer.type
// v5; constant is true (i.e. "call") or false (i.e. "transaction")
functionFragment.constant
// v4
interface.events.Transfer.anonymous
interface.events.Transfer.inputs
interface.events.Transfer.name
// v5
const eventFragment = interface.getEvent("Transfer");
eventFragment.anonymous
eventFragment.inputs
eventFragment.name
// v4
const functionSig = interface.functions.transfer.signature
const sighash = interface.functions.transfer.sighash
const eventSig = interface.events.Transfer.signature
const topic = interface.events.Transfer.topic
// v5
const functionSig = functionFragment.format()
const sighash = interface.getSighash(functionFragment)
const eventSig = eventFragment.format()
const topic = interface.getTopic(eventFragment)

##
Utilities

###
Renaming

TODO

##
Wallet

###
Mnemonic Phrases

The mnemonic phrase and related properties have been merged into a single `mnemonic` object, which also now includes the `locale`.

// v4
wallet.mnemonic
wallet.path
// v5
// - Mnemonic phrase and path are a Mnemonic object
// - Note: wallet.mnemonic is null if there is no mnemonic
wallet.mnemonic.phrase
wallet.mnemonic.path
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