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This article focuses on "how to use modifiers to make Solidity more readable". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor learn how to use modifiers to make Solidity more readable.

A modifier is a function that can be applied to other functions. It is useful to ensure that certain prerequisites are met before calling a function. Let's take a simple example. In contracts we've already written, we often check whether the caller of the function is the owner of the contract:

Function increment () public {if (owner = = msg.sender) {/ / We check who calls the function count = count + 1;}}

Imagine if our smart contract has multiple functions that can only be called by the owner, what if the owner = = msg.sender part needs to be refactored? This is where modifiers will help us. Let's look at the first modifier:

Modifier isAdmin () {require (msg.sender = = owner); _;} function increment () public isAdmin {count = count + 1;}

Our modifier looks like a function. The require () function evaluates the condition and throws an exception if the condition is not met, which stops the execution of our smart contract. The _ keyword tells the compiler to replace _ with a function body.

Like functions, modifiers can accept parameters. Suppose we can have multiple users and want to check ownership, take a look at the following code:

Modifier onlyBy (address _ account) {require (msg.sender = = _ account); _;} function increment () public onlyBy (owner) {count = count + 1;}

As you can see, our modifiers are more generic, which allows us to do more.

You can also write the most generic modifiers that run only if any condition is true:

Modifier onlyIf (bool _ condition) {require (_ condition); _;} function increment () public onlyIf (msg.sender = = owner) {count = count + 1

By specifying multiple modifiers in a space-separated list, multiple modifiers are applied to the function and evaluated in the order in which they are displayed.

Modifier onlyIf (bool _ condition) {require (_ condition); _;} function increment () public onlyIf (msg.sender = = owner) onlyIf (count < 200) {count = count + 1;} at this point, I believe you have a deeper understanding of "how to use modifiers to make Solidity more readable". You might as well do it in practice! Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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