How can I use the return value in a try/catch?

Question

I'm doing an external call in a try/catch block. This external call provides me with return value that I'll use further down the line.

However, I'm getting a TypeError: Try can only be used with external function calls and contract creation calls.

How can I use the values returned by the external call while in a try/catch?

Here the line:

uint256 x;
uint256 y;

try
    (x, y) = IVault(_vault).liquidate()
{
   // Do something
} catch {
   // Do something else
}

Yakitori · Accepted Answer · 2022-12-31 00:10:17Z

3

Ok, I found the issue: it's possible to manage the return value by using the returns keyword:

try
    IVault(_vault).liquidate() returns (uint256 _x, uint256 y)
{
   // Do something
} catch {
   // Do something else
}

answered Dec 31, 2022 at 0:10

Yakitori

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VX3 · Accepted Answer · 2022-12-30 23:12:35Z

0

You can use an ordinary if statement to check if the function call was successful

answered Dec 30, 2022 at 23:12

VX3

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Hello. To improve the quality of your answer, you could provide an example of what yo uare proposing.
– Itération 122442
Jan 2 at 8:27
It's in the answer. If someone doesn't know how to do an if statement then all I can do is provide a code snippet, which the user has not asked for. In any case, he has found another way around it which differs from my approach.
– VX3
Jan 6 at 20:09
SE has a simple model: Explanation + example.
– Itération 122442
Jan 6 at 20:13
No - SE has a model of giving a clear and concise answer. Examples are not mandatory if an explanation is sufficient. What more do you need to know about an if statement? If the OP needs further clarification they can ask it themselves.
– VX3
Jan 6 at 20:35

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2 Answers 2