REPL: Warning about underscore

[xixixao]

I can't find an existing issue for this:

$ node -v
v7.9.0
$ coffee -v
CoffeeScript version 1.12.5
$ coffee
coffee> 4
Expression assignment to _ now disabled.
4
coffee>

Node REPL is constantly warning that assignment to underscore is now disabled. Latest Node, latest CS.

[vendethiel]

See nodejs/node#5431 for rationale

[xixixao]

@vendethiel Might explaining specifically for CoffeeScript? I am not using any explicit _ assignment I'm aware of.

[vendethiel]

Look at the repl code. We generate an assignment to _ to force it to be an expression.

[lydell]

Couldn't we assign to some other name, then?

[vendethiel]

Yes, we need to do this. My comment didn't mean we should close the issue.

[GeoffreyBooth]

We do this because the Node REPL itself treats _ as a special case, assigning it to the last returned value:

$ node
> a = 1
1
> _
1

As @vendethiel noted above, see nodejs/node#5431.

[xixixao]

Can we just assign to __ ? This is super annoying in the REPL.

[GeoffreyBooth]

Resolved by #4559.