From Clause

The from clause restricts who may invoke a route by checking msg::sender against an expected entity (or address) identity.

On EVM this lowers to a require(msg.sender == …) style guard.

Syntax

credit(account: address, amount: U256)
    from Shop(m_shop_id) : throw Unauthorized()
=> []

The optional : throw ErrorName(...) supplies a named custom error when the sender check fails (see Custom Errors).

Multiple senders

Join alternatives with | (OR):

update_price(asset: String, price: U256)
    from Oracle(m_oracle_id) | Admin(m_admin_id) : throw Unauthorized()
=> []

From with where

from runs before where:

execute_trade(amount: U256)
    from Broker(m_broker_id) : throw Unauthorized()
    where amount > 0 : throw ZeroAmount()
    && m_status == Status::Active : throw Paused()
=> []

EVM arity rules (V33)

from Entity(...) takes as many arguments as the target entity has identity members (zero for singletons: from Registry()).

extern entity targets skip V33. Plain address members used as senders can also be compared with where msg::sender == m_owner when you do not need entity-typed address prediction.

On EVM, from Entity(args) compares msg.sender to the same CREATE2 expression as Entity.address(args), so authentication and addressing stay in sync. See Deterministic Addresses.

When to use `from`

Scenario	Prefer
Public caller actions	No `from` (or `where` on `msg::sender`)
Callbacks from a known Cambrian entity	`from Entity(…)`
Admin / oracle entities with predicted addresses	`from Entity(…)` on EVM
Plain address stored in a member	`where msg::sender == m_owner`

where msg::sender == m_owner : throw Unauthorized()

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