[英]Unable to print in a procedural macro function declaration in Rust
I am using a proc_macro
and want to print some verbose for debugging.我正在使用proc_macro
并想打印一些详细信息以进行调试。 The println!
println!
statement doesn't print anything.语句不打印任何内容。
This is the macro call:这是宏调用:
decl_module! {
/// The module declaration.
pub struct Module<T: Trait> for enum Call where origin: T::Origin {
// A default function for depositing events
fn deposit_event() = default;
/// Allow a user to claim ownership of an unclaimed proof
fn create_claim(origin, proof: Vec<u8>) -> DispatchResult {
// Verify that the incoming transaction is signed and store who the
// caller of this function is.
let sender = ensure_signed(origin)?;
println!("send is: {}", sender);
// Verify that the specified proof has not been claimed yet or error with the message
ensure!(!Proofs::<T>::exists(&proof), "This proof has already been claimed.");
// Call the `system` pallet to get the current block number
let current_block = <system::Module<T>>::block_number();
// Store the proof with the sender and the current block number
Proofs::<T>::insert(&proof, (sender.clone(), current_block));
// Emit an event that the claim was created
Self::deposit_event(RawEvent::ClaimCreated(sender, proof));
Ok(())
}
/// Allow the owner to revoke their claim
fn revoke_claim(origin, proof: Vec<u8>) -> DispatchResult {
// Determine who is calling the function
let sender = ensure_signed(origin)?;
// Verify that the specified proof has been claimed
ensure!(Proofs::<T>::exists(&proof), "This proof has not been stored yet.");
// Get owner of the claim
let (owner, _) = Proofs::<T>::get(&proof);
// Verify that sender of the current call is the claim owner
ensure!(sender == owner, "You must own this claim to revoke it.");
// Remove claim from storage
Proofs::<T>::remove(&proof);
// Emit an event that the claim was erased
Self::deposit_event(RawEvent::ClaimRevoked(sender, proof));
Ok(())
}
}
}
It is taken from here .它是从这里拍摄的。 I added the following line:我添加了以下行:
println!("send is: {}", sender);
I am running a blockchain(Polkadot dApp), in the terminal (or anywhere), I could not see the output message.我正在运行一个区块链(Polkadot dApp),在终端(或任何地方),我看不到输出消息。 Note: everything is working fine but I am unable to print.注意:一切正常,但我无法打印。
This macro call generates code that contains a print statement.此宏调用生成包含打印语句的代码。 It does not run that code.它不运行该代码。 You will not see the print output until the code is run and you call create_claim
.在运行代码并调用create_claim
之前,您不会看到打印输出。
If you want to debug your macro call, there are severaltools for macros-by-example, but I don't know if they also work for procedural macros or if there are equivalents.如果你想调试你的宏调用,有几个宏示例的工具,但我不知道它们是否也适用于程序宏,或者是否有等价物。
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