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Understanding the “No function or associated item named create_type” error in Solana
As a developer building applications on the Solana blockchain, I often encounter errors related to smart contract development. One such error is the “No function or associated item named create_type” error, which can occur when trying to use a custom type defined in Solana.
Problem: Error E0599
In the provided code snippet:
use solana_program::program_error::{error, ErrorKind};
use solana_program::pubkey::Pubkey;
use solana_type::create_type;
// Define your custom type here
pub fn main() -> Result {
// Your program logic is here...
// Create a new transaction with the custom type
let tx = create_type!(T) as &_, 10u64; // T is your custom type, and "as &_"
}
The error occurs because the create_type! function is missing from the Solana SDK. Instead, you should use program_error::ErrorKind::CustomType to resolve this specific error.
Bug Fix
To fix the error, you need to define a custom type and then use it when creating transactions. Here is the updated version of the code:
use solana_program::program_error::{error, ErrorKind};
use solana_program:: pubkey::Pubkey;
use std::mem;
// Define your custom type here
pub fn main() -> Result {
// Create a new transaction with a custom type
let tx = create_type!(T) as &_, 10u64; // T is your custom type, and "like &_"
// Check if the transaction was successfully created
match tx {
Ok(_) => println!("The transaction was successfully created"),
Err(err) => error!("Failed to create transaction", err),
}
}
Understanding Custom Types
In Solana, you can define custom types using the create_type! macro. This macro is used to generate code to create custom types.
Here’s an example of a basic custom type:
use salt_type::create_type;
pub type MyCustomType = u8;
With this definition, we can use it when creating transactions:
pub fn create_transaction() -> ProgramResult {
// Create a new transaction with a custom type
let tx = MyCustomType::new(10);
OK(())
}
Conclusion
In this article, we saw how to fix the “no function or associated item named create_type” error in Solana. By defining your own custom types and using them when creating transactions, you can create more complex blockchain applications.
Don’t forget to always check the official Solana documentation for the latest information on programming languages and types.