Title: Ethereum: calls itself by fails when it matches structures
Introduction
Ethereum is a decentralized platform that allows developers to build and implement intelligent contracts, which self -execute contracts with the conditions of the written agreement directly in code lines. However, a common problem that can arise in Ethereum is when a contract calls it to use the .Call method and tries to pass a structure (a data structure) as an argument.
problem
When a contract is called, use the .Call method, a specific type of data, such as a whole number or a string, is usually expected. However, when you pass a structure as an argument, Ethereum’s solidity compiler casts an error because of his lack of support for structures, in the same way that the matrices are made.
The exit of the resulting errors is:
`Solidity
Error: Failed to decode the exit: Error: Data type is not allowed: "Structure"
This can cause significant problems when trying to resort to a position on a contract, because the contract may try to access the structure of the structure or try to assign one of its members.
problem
In solidity 0.6.0 and subsequent versions, the key word "data" was eliminated from structures. This means that when using.Call, you can no longer pass structures directly as arguments for functions. Instead, you must use paintings or other data structures to represent the fields of structure.
To remedy this problem, developers must create a new feature that will return a painting adjustment or structure:
Solidity
Pragma solidity ^0.6,0;
Struct mystruct {
UINT256 X;
string y;
}
MyFunction Function () Pure Pure Returns (Mystruct) {
Returns mystruct (x: 1, y: "greeting");
}
Solution
To solve this problem, developers can use the following approaches:
- Create a new function that returns a painting : As shown above, create a new feature that takes data and returns a series of values.
- Use Structure Insead paintings
: Replace "Mystruct Structure with a painting:
`Solidity
Pragma solidity ^0.6,0;
Struct myarray {
UINT256 X;
string y;
}
MyFunction () Pure Pure Returns (Myarray)
Return Myarray (X: 1, Y: "Hi");
}
- Use libraries that accept structures : Some libraries, such as "open Zeppelin, offer functions for working with structures in solidity.
Conclusion
In conclusion, the passage of a structure to a contract using the.Call` method can lead to an error due to the lack of ETHREUM support for structures. To solve this problem, developers must create new functions that return paintings instead of structures or use libraries that provide functions for working with structures. Following the thesis stages, developers can be ensured that their contracts work properly and do not face errors when they match the structures as arguments.
additional resources
- Solidity documentation: [
- Openzeppelin Documentation: [ Contract-abi-signatures
Note: This article is intended to provide a general image of the problem and potential solutions, but it may not cover all possible scenarios or edge cases.
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