รูปแบบพร็อกซีโปร่งใสและการจัดวางหน่วยความจำจัดเก็บ

You have seen UUPS and the Diamond standard. Both rely on a foundational idea: a proxy holds the storage and forwards calls to a separate logic (implementation) contract. Upgrading means pointing the proxy at new logic.

The magic behind proxies is delegatecall. It runs the logic contract's code but in the proxy's storage context, using the proxy's msg.sender and balance.

So storage lives in the proxy; behavior lives in the implementation.

A proxy forwards every unknown call to the implementation using assembly delegatecall in its fallback.

If the proxy itself has an upgradeTo function and the logic also has a function with the same selector, calls become ambiguous. The Transparent Proxy pattern solves this by routing based on the caller.

In a Transparent Proxy, the admin address can call admin functions (like upgrade) but cannot reach the implementation. Everyone else is always forwarded to the implementation. This removes clashes.

Both proxy and logic write to the same storage. If they used slot 0 for different variables, they would corrupt each other. Proxies store admin and implementation at fixed pseudo-random slots (EIP-1967) to avoid collisions.

The proxy reads and writes that fixed slot directly with assembly so it never collides with logic variables.

When upgrading the logic you must preserve the order and types of existing storage variables. New variables go at the end.

• Never reorder existing variables
• Never change a variable's type
• Never insert a new variable before old ones

Inheritable base contracts reserve space for future variables with a __gap array so child contracts do not collide after an upgrade adds fields to the base.

Constructors run only on the logic contract's own deployment, not through the proxy. Upgradeable contracts use an initialize function guarded so it runs exactly once.

Transparent proxies put the upgrade logic in the proxy (more deployment gas, simpler logic). UUPS puts it in the implementation (cheaper proxy, but you must include upgrade code in every version). Choose based on cost and team discipline.

You learned the Transparent Proxy pattern:

• delegatecall runs logic in the proxy's storage
• Admin-vs-user routing avoids function clashes
• EIP-1967 fixed slots and __gap arrays prevent collisions
• Use initialize, preserve storage layout, append new variables

Follow these rules and upgrades stay safe.