On calls, pull defaultBlock from web3

[wbt]

Issue:

Function calls using @truffle/contract (.call()) act as if web3.eth.defaultBlock == 'latest', even when it isn't.

The workaround is to add a parameter at the end of the parameter list for every call() which is web3.eth.defaultBlock.

This is not intuitive, not consistent with a prior major version, and the change does not appear easy to find in documentation. It's also not clear that this is the best choice for behavior.

I think the behaviour is due to the line: let defaultBlock = "latest";

That was added in this commit by @cgewecke back on Jun 10, 2018, but I can't really find why; I don't see any associated PR/discussion.

This PR proposes changing that line to let defaultBlock = this.web3.eth.defaultBlock; but hasn't been tested. The intended result includes:

• Backwards compatibility: if you are using the workaround that you currently have to use, or if you are leaving the defaultBlock as 'latest' all the time, no behavior will change and no code changes are required.
• If someone is changing web3.eth.defaultBlock, calls should respect that.

[gnidan]

I think the build is failing because of this inside function() {}, but that's easily corrected. I also suggested a bit of defensive coding with the || "latest", just to be on the safe side.

Apart from that, I think this change makes sense and shouldn't cause problems! Will approve once tests pass. Thanks for this!

[gnidan]

@eggplantzzz if you have a second, could you get your eyes on this too? Would just like another opinion!

[wbt]

Note that it's not 100% clear to me, having not yet fully tested this, whether changes to the global web3.eth.defaultBlock are reflected in the web3 referenced in the "this"/constructor object. If not, I think the edit would probably do no harm, but also not accomplish the intended goal.

[gnidan]

whether changes to the global web3.eth.defaultBlock are reflected in the web3

My guess is that almost certainly not, since @truffle/contract constructs its own web3

[wbt]

In that case, this should probably be considered an Issue report which had a specific suggested fix but where that suggestion was likely ultimately insufficient by itself.

[eggplantzzz]

This looks like it should be fine to add to me