What does a payable parameter mean in constructor?

Question

constructor(
    uint _biddingTime,
    address payable _beneficiary
) public {
    beneficiary = _beneficiary;
    auctionEndTime = now + _biddingTime;
}

This code is from the contract SimpleAuction in the solidity documentation. https://solidity.readthedocs.io/en/v0.6.4/solidity-by-example.html

What does a payable parameter mean?

Answer 1

In this example:

constructor(
    uint _biddingTime,
    address payable _beneficiary
)

address payale

casts _beneficiary as Type: address payable

In Solidity an address can be payable which attaches the .send() and .transfer() methods. Otherwise, it's the same as address _beneficiary.

A constructor, or other function, can also have the payable modifier which is sort of what I thought the question was about, because on the title.

contructor(Type arg, Type arg) public payable { ...

With that usage, one can send Ether with the deployment transaction and it will add to the deployed contract's balance.

Hope it helps.

Answer 2

In example you mentioned address payable _beneficiary means that _beneficiary can receive ethers. With having payable keyword now _beneficiary.send(etherAmount) and _beneficiary.transfer(etherAmount) can be used in the contract logic.