I'm getting a 'duplicate argument name' with the below code

func location(name, city string) (name, continent string) {
    switch city {
    case "New York", "LA", "Chicago":
        continent = "North America"
    default:
        continent = "Unknown"
    }
    return
}

func main() {
    name, continent := location("Matt", "LA")
    fmt.Printf("%s lives in %s", name, continent)
}

go version go1.4.2 darwin/amd64

In your Bitcoin exercise, you calculate the number of coins for "Augustus" as 10, when it should be 13, leaving you with -1 coins. I'd submit a pull request, but I'm not sure if you'd rather use a different name, increase the # of coins, etc.

func location(name, city string) (name, continent string)
should be

func location(name, city string) (region, continent string)

Running the current cod in the playground will return:

prog.go:5: duplicate argument name

However, the linked playground code is correct.

I would suggest adding:

import "net/http"

http://www.golangbootcamp.com/book/basics#sec-pointers

Following the setup in Chapter 9, I found the repos at the bottom have moved from code.google.com.

Stevens-MacBook-Pro:go cittzl$ go get code.google.com/p/go.tools/cmd/godoc
the code.google.com/p/go.tools/cmd/godoc command has moved; use golang.org/x/tools/cmd/godoc instead.

Stevens-MacBook-Pro:go cittzl$ go get code.google.com/p/go.tools/cmd/vet
can't load package: the code.google.com/p/go.tools/cmd/vet command has moved; use golang.org/x/tools/cmd/vet instead.

On http://www.golangbootcamp.com/book/tricks_and_tips
search for "dramatic twist", the rest of that chapter is not correctly formatted

Ideally the font would be fixed-width and small enough to not wrap lines where it shouldn't.

Please compile new version for online book

I found,
Chapter 2: The Basics |> 2.7 Functions, signature, return values, named results
The content of online book , still old than source book

2.7 Type Assertion

package main

import (
    "fmt"
    "time"
)

func timeMap(y interface{}) {
    z, ok := y.(map[string]interface{})
    if ok {
        z["updated_at"] = time.Now()
    }
}

func main() {
    foo := map[string]interface{}{
        "Matt": 42,
    }
    timeMap(foo)
    fmt.Println(foo)
}

Here, timeMap func is a magic to me. You neither specify any return value for this nor pass a pointer to it while calling, but it is working fine. Can you explain the logic in it?

Thanks
p.s Your book is awesome!

You introduce the idea of type assertion with examples of interfaces and structures.

1. these are complicated syntactical examples that are difficult to understand in the realm of the basic language. Dot notation with some shit in-between parens:

y.(map[string]interface{})
value.(type)

2. the reader has not been introduced to the concepts of interfaces or structs yet so it cannot be understood in this sequence.

Consider moving this section to advanced concepts and perhaps referencing this:

ex 3.3 Type assertion

"for more advanced subject of type conversion, please see section 2001.1" etc

EDIT: I think the whole document could use a good edit so that the examples and subjects flow with what is learned. Throughout the book, examples are presented using concepts and techniques that have not yet been introduced and explained, therefore it frustrates.

Is this book getting updated or is this project abandoned?
Last updated date is a year ago.

String change - 's/page/package/g' in the following text I believe.

"Pi is exported and can be accessed from outside the page, while pi isn’t available."
2.6 Exported names

Hi everyone! Exist any translating to portuguese Brazil? I'm desiring get started!

It seems the code in the playground (http://play.golang.org/p/aOSABxXoiU) linked at the end of section 2.7 (https://github.com/GoBootcamp/book/blob/master/chapters/basics.md#422) doesn't match the code given in the example just above it.

Hi Matt
As stated in PR #38, we still have a problem of goroutine leak and channel leak. Some Walk invocations will never return because they are stuck writing in a channel that is not read anymore. I revealed the leaks on my computer by calling Same a large number of times on different trees : the memory footprint of the program, as shown by top, kept growing and growing.

Below I will suggest two possible fixes.

My feeling about concurrency in Go is :

• it makes writing correct concurrent code easier than in other languages ;
• it doesn't prevent from shooting oneself in the foot ;
• it doesn't change the fact that concurrent design in general is difficult and subtle ;
• goroutines and channels have their own subtlety, that we must be aware of ;
• we should stick to the convention that "the writer closes the channel when it's done writing" (and not "the reader closes the channel when it's done reading").

Possible fix 1 : "drain" the channels after use, i.e. loop to read all the potential unused values in ch1 and ch2. So we ensure recWalk will finish and Walk will close the channel, so the goroutines can properly end and the channels will be garbage collected.
Advantage : it is short and straightforward to implement.
Drawback : completing the Walk of a big tree is an undesirable amount of work when the tree comparison returns false early : we should not have to process the remainder of the tree.

Possible fix 2 : create a quit channel for each tree, as described in this slide.
Advantage : no more leaks, no useless work.
Drawback : the code is lengthier and more difficult to write and read.

What do you think?
I can make a pull request for (fix 1) or (fix 2) of the go code, and the paragraph would need to be updated to explain the plumbing.

Cheers

Hi,

there are a couple of dead links in the book, which reference code.google.com.
These packages seem to be moved to golang.org.

I will fix this and create a PR for that.

Mattagohni

In the book, the example is shown as

`func location(name, city string) (region, continent string) {
switch city {
case "New York", "LA", "Chicago":
continent = "North America"
default:
continent = "Unknown"
}
return
}

func main() {
region, continent := location("Matt", "LA")
fmt.Printf("%s lives in %s", region, continent)
}`

But, the Go Playground shows

`package main

import "fmt"

func location(city string) (region, continent string) {
switch city {
case "Los Angeles", "LA", "Santa Monica":
region, continent = "California", "North America"
case "New York", "NYC":
region, continent = "New York", "North America"
default:
region, continent = "Unknown", "Unknown"
}
return
}

func main() {
region, continent := location("Santa Monica")
fmt.Printf("Matt lives in %s, %s", region, continent)
}
`

The Playground seems to be more correct than the code shown in the book text.

Section 3.3 we are covering Type Assertion http://www.golangbootcamp.com/book/types#sec-type-assertion.

The examples in the book are going over interface type assertions. I, being new to go, don't quite understand interfaces yet. So these examples are not helpful at all.

It would be better if:

1. we covered what an interface is before section 3
2. used a different type in the examples.

Similarly, in this example we are also going over maps which aren't covered till the next section in section 4.

Maybe Type Assertion should be moved to after all these other concepts have been covered. So that the code examples aren't so confusing to new go programmers.

What license is this awesome book under? Could you add a LICENSE file with this information?