# Proxyable¶

## Description¶

This contract is designed to operate in tandem with Proxy. In fact, in order to function properly, every contract operating behind a CALL-style proxy must inherit Proxyable to ensure that the message sender is set and that events are correctly emitted.

This contract can support two proxies simultaneously. Events can be emitted independently from each proxy, but it is sensible to restrict event emission to a single proxy in most cases.

Source: Proxyable.sol

## Variables¶

### proxy¶

The address of the main proxy that this contract operates underneath. It is this address that events should be emitted from using Proxy._emit.

Type: Proxy public

### integrationProxy¶

The address of an additional proxy which can be used to forward contract calls to this contract. Generally speaking, events should not be passed to the integrationProxy.

In the case of the Synthetix contract, this integrationProxy is an instance of the ERC20 proxy.

Type: Proxy public

### messageSender¶

The caller of the proxy in the current invocation. This variable is set to the value of msg.sender visible to the proxy before every function call by that Proxy to this Proxyable. Once set, messageSender should be used in place of msg.sender wherever it is used in contracts inheriting Proxyable.

All functions which make use of messageSender should have one of the modifiers provided by the Proxyable interface, otherwise users who call the contract directly rather than through the proxy will be executing with stale values of messageSender.

Functions which do not require messageSender need not apply any of the proxy modifiers, but care must be taken when applying other function modifiers within a proxyable contract. For example, see optionalProxy_onlyOwner.

Type: address

## Functions¶

### constructor¶

Initialises this contract's proxy and the inherited Owned instance.

Details

Signature

constructor(address _proxy, address _owner) public

Superconstructors

Emits

### setProxy¶

Sets this contract's primary proxy. setProxy cannot be called through a proxy.

Details

Signature

setProxy(address _proxy) external

Modifiers

Emits

### setIntegrationProxy¶

Sets this contract's secondary proxy. setIntegrationProxy cannot be called through a proxy.

Details

Signature

setIntegrationProxy(address _IntegrationProxy) external

Modifiers

### setMessageSender¶

This is used by proxies to set messageSender before forwarding a function call. This is only callable by the proxy or integrationProxy.

Details

Signature

setMessageSender(address sender) external

Modifiers

## Modifiers¶

### onlyProxy¶

Reverts the transaction if the actual msg.sender (not messageSender) is not the proxy or the integration proxy.

### optionalProxy¶

This modifier allows a function to be called through the proxies, or alternatively to be called directly for a small gas savings.

It operates simply: if the caller is not either the proxy or the integration proxy, then overwrite messageSender with msg.sender, otherwise use whatever it was set to by the proxy.

### optionalProxy_onlyOwner¶

This modifier is largely the same as optionalProxy, but it disallow callers who are not the contract owner. This modifier exists because Owned.onlyOwner checks msg.sender, and not messageSender.

## Events¶

### ProxyUpdated¶

proxyAddress has been set as the new proxy.

Signature: ProxyUpdated(address proxyAddress)