Link an address to a contract as a library in deployer

• I’ve asked for help in the Truffle Gitter before filing this issue.

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Issue

My contract has a libary Lib {} in it. I would like to use an existing library in the migrations script.

Something like:

deployer.linkAddressAsLibrary('0xabcde...', 'AnExistingLibraryOnChain')

[haltman-at]

Hey, I just had an idea for how to handle this. (Which I am realizing now was implcitly suggested by @ayusht11 above, but we don’t seem to have taken much notice of it at the time, presumably because it wasn’t given as an explicit suggestion.)

We could handle this by allowing the first argument of link to be a library instance rather than a library class. Then you could do await library = Library.at(address); deployer.link(library, Contract). That seems like it would be a fairly natural extension of the current syntax. What do people think of that?

[bwheeler96]

@gnidan This actually already works, the key is that .link returns a thenable, so it must be awaited. Here is what works for me

await MyContract.link('CustomLibraryName', '0xabcde...')

Alternatively you could use .then() syntax.

Also, it should be noted that my deploy script must be setup like this for async to work:

async function doDeploy() {
  await ...
}

module.exports = (deployer, network) => {
  deployer.then(async () => {
    await doDeploy(deployer, network)
  })
}