how do you chain commands on several lines in go?

Question

I want to chain commands this way :

var cmdGroups = []*commands.CmdGroup {
    commands.MakeCmdGroup("foo", cmd1, cmd2, cmd3).AddConstraint(cmd1, cmd2).AddConstraint(cmd2, cmd1, cmd3),
    commands.MakeCmdGroup("bar", cmd1, cmd4).AddConstraint(cmd1, cmd4),
}

I'd like to split my chains on several lines for 80-column-lengths reasons, but Go won't let me compile this :

var cmdGroups = []*commands.CmdGroup {
    commands.MakeCmdGroup("foo", cmd1, cmd2, cmd3)
            .AddConstraint(cmd1, cmd2)
            .AddConstraint(cmd2, cmd1, cmd3),
    commands.MakeCmdGroup("bar", cmd1, cmd4)
            .AddConstraint(cmd1, cmd4),
}

what can I do ?

Answer 1

As FUZxxl pointed out, your problem is the automatic insertion of semicolons. The spec says:

When the input is broken into tokens, a semicolon is automatically inserted into the token stream at the end of a non-blank line if the line's final token is

• an identifier
• an integer, floating-point, imaginary, rune, or string literal
• one of the keywords break, continue, fallthrough, or return
• one of the operators and delimiters ++, --, ), ], or }

You have a function call, which counts for a ) so a semicolon is added at the end of the line.

To circumvent automatic semicolon conversion you can write your calls in one of the following ways:

Use the . instead of semicolon:

x.
Method(p1,p2,p3)

Break after beginning of parameter list instead of before the function:

x.Method(
   p1,p2,p3, // , at the end is important to prevent semicolon insertion
)

If you dislike the methods above, you can (as of go1.1) treat the methods as first class citizens and temporarily create shortcuts which might be shorter:

f = x.Method
f(p1,p2,p3).f(p3,p4,p5)

I haven't thought enough with this example. f(...).f(...) is of course not possible, as the return value of f has no member f. One would have to reassign f. So you gain nothing from that.