Try Catch, Function returns x values, but returns clause has x-1 variables

Question

Disclaimer

I came across an not so well documented issue so I decided to share it and show the solution I found.

This is a very simple problem with a very simple solution, I just didn't found any other topic mentionning it.

I hope this can help someone, someday. If you have a better approach for this let me know!

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Context

In ContractA, I have a function getInfo() that returns 3 parameters :

function getInfo() public pure returns (uint type, uint id, string memory name) {
  return (0, 1, "info");
}

In ContractB, I have a function retreiveInfo() that uses a try catch block to call ContractA.getInfo().

function retreiveInfo() public view {
  try ContractA.getInfo() returns (uint _type, uint _id, string memory _name) {
    // Do something with _type and _id
    // Compiler warning, unused variable
  } catch {}
}

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Problem

The problem is that I only need 2 values out of the 3: _type and _id. So the compiler is giving me a warning for an unused variable.

I tried to use this syntax:

try ContractA.getInfo() returns (uint _type, uint _id, )

But compiler returns error "Unexpected trailing coma in parameter list".

So I tried not to include it at all:

try ContractA.getInfo() returns (uint _type, uint _id)

Again, compiler error "Function returns 3 values, but returns clause has 2 variables".

---

Solution

The solution I found is to use an temporary variable:

try ContractA.getInfo() returns (uint _type, uint _id, string memory)

Answer 1

Solution

The solution I found is to use an temporary variable:

try ContractA.getInfo() returns (uint _type, uint _id, string memory)