# Initializable *This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer function so it can only be called once. The {initializer} modifier provided by this contract will have this effect. TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}. CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.* --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://contracts.synapseprotocol.com/elin/contracts-upgradeable/proxy/initializable.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.