Portable Cloud Programming with Go Cloud

Re:Portable Cloud Programming with Go Cloud by sbjs on Tuesday July 24, 2018 @12:46PM (#17602755)

The article has two examples of how I already find Go to be inconsistent and/or surprising:

    w, err := b.NewWriter(ctx, "gopher.png", nil)
    ...
    _, err = w.Write(data)
    ...
    if err := w.Close(); err != nil

Why is := used on the first line but = used on the second line, and then := used again on the third line? I get that you use := when introducing a new variable, and = when just assigning, the third line is not really introducing a new variable, since err is still in scope... or is it?

Not to mention, what is the last argument `nil` supposed to represent? In most high quality Node.js libraries, functions/constructors will take an optional options object so you can omit it, or pass an object like { timeout: 300 } to it.

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Re:Portable Cloud Programming with Go Cloud by ssambros on Tuesday July 24, 2018 @01:32PM (#17603217)

Third line ':=' is not required, you can reuse globally scoped 'err' with '=' as well; unless you want to preserve the current value of global 'err' for future use (which would be confusing).

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Re:Portable Cloud Programming with Go Cloud by skj on Tuesday July 24, 2018 @12:57PM (#17602868)

The third line has a new err inside the if statement's scope.

It's equivalent to

    { // begin new scope here
      err := w.Close()
      if err != nil {
        foo
      } else {
        bar
      }
    }

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Re:Portable Cloud Programming with Go Cloud by elithrar on Tuesday July 24, 2018 @12:56PM (#17602858)

> the third line is not really introducing a new variable, since err is still in scope... or is it?

The "if" block creates a new scope.

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Re:Portable Cloud Programming with Go Cloud by ironjunkie on Tuesday July 24, 2018 @02:20PM (#17603668)

agreed that the := that can be used when one new var is introduced but not the others is extremely confusing.

I also hate the inconsistent behavior when you check multiple errors in a row, the first one will get := but not the second one (if you don't put those in a if statement, which I never do). But now if for some reason, you remove the first := statement, the code will error on the second one, that needs to be changed from = to :=

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