tx_context.md

Module 0x2::tx_context

• Struct TxContext
• Constants
• Function sender
• Function signer_
• Function epoch
• Function new_object
• Function ids_created
• Function derive_id

use 0x1::signer;

Struct TxContext

Information about the transaction currently being executed. This cannot be constructed by a transaction--it is a privileged object created by the VM and passed in to the entrypoint of the transaction as &mut TxContext.

struct TxContext has drop

Fields

signer: signer

A signer wrapping the address of the user that signed the current transaction

tx_hash: vector<u8>

Hash of the current transaction

epoch: u64

The current epoch number.

ids_created: u64

Counter recording the number of fresh id's created while executing this transaction. Always 0 at the start of a transaction

Constants

Expected an tx hash of length 32, but found a different length

const EBadTxHashLength: u64 = 0;

Number of bytes in an tx hash (which will be the transaction digest)

const TX_HASH_LENGTH: u64 = 32;

Function sender

Return the address of the user that signed the current transaction

public fun sender(self: &tx_context::TxContext): address

Implementation

public fun sender(self: &TxContext): address {
    signer::address_of(&self.signer)
}

Function signer_

Return a signer for the user that signed the current transaction

public fun signer_(self: &tx_context::TxContext): &signer

Implementation

public fun signer_(self: &TxContext): &signer {
    &self.signer
}

Function epoch

public fun epoch(self: &tx_context::TxContext): u64

Implementation

public fun epoch(self: &TxContext): u64 {
    self.epoch
}

Function new_object

Generate a new, globally unique object ID with version 0

public(friend) fun new_object(ctx: &mut tx_context::TxContext): address

Implementation

public(friend) fun new_object(ctx: &mut TxContext): address {
    let ids_created = ctx.ids_created;
    let id = derive_id(*&ctx.tx_hash, ids_created);
    ctx.ids_created = ids_created + 1;
    id
}

Function ids_created

Return the number of id's created by the current transaction. Hidden for now, but may expose later

fun ids_created(self: &tx_context::TxContext): u64

Implementation

fun ids_created(self: &TxContext): u64 {
    self.ids_created
}

Function derive_id

Native function for deriving an ID via hash(tx_hash || ids_created)

fun derive_id(tx_hash: vector<u8>, ids_created: u64): address

Implementation

native fun derive_id(tx_hash: vector<u8>, ids_created: u64): address;