[go-nuts] Re: go routines not being deallocated

[Trig]

>From further research (and anybody correct me if this is wrong), when the 
GC does collect memory the profile shrinks, but *no memory is returned to 
the system*. Any future allocations will try to use memory from the pool of 
previously collected objects before asking the system for more.  This is 
why things are behaving this way.

On Sunday, April 18, 2021 at 12:34:44 PM UTC-5 Trig wrote:

> Also, I don't think it's the Stack.  If you replace Alloc with 
> HeapAlloc... it's all there.
>
> On Sunday, April 18, 2021 at 12:33:20 PM UTC-5 Trig wrote:
>
>> Correct... the example using time.Sleep didn't run on the playground.  
>> The original post I made, I provided the link with just a goroutine with an 
>> empty function.
>>
>> At least you were able to reproduce what I'm inquiring about.  I'll look 
>> further into this, but surely unused and finished goroutines don't leave 
>> stuff laying around like that.
>>
>> On Sunday, April 18, 2021 at 3:47:10 AM UTC-5 Brian Candler wrote:
>>
>>> What do you mean by "It won't work on the playground"?  It runs for me.  
>>> Are you saying you get different results when running locally?  If so, what 
>>> version of go are you running locally, on what platform, and what do you 
>>> see?
>>>
>>> Or are you saying the problem is really with something like this?
>>> https://play.golang.org/p/Q91Qd-DvvKx
>>>
>>> That indeed fails to run in the playground - it exits with signal 9 
>>> (128+9=137)
>>>
>>> Running locally with go 1.16.3 under macOS (Intel) I see:
>>>
>>> Allocs before: 82696
>>> Allocs while running: 51496728
>>> Allocs after: 40384112
>>> Allocs after: 40384112
>>> Allocs after: 40384112
>>> Allocs after: 40384112
>>> Allocs after: 40384112
>>>
>>> That is 40MB that apparently isn't reclaimed, but it does get reused if 
>>> you run more goroutines:
>>> https://play.golang.org/p/YcMTlLYxXAP
>>>
>>> I don't know why that is.  It's about 400 bytes per goroutine.  Stack 
>>> perhaps?
>>>
>>

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[go-nuts] Re: go routines not being deallocated

[Trig]

Also, I don't think it's the Stack.  If you replace Alloc with HeapAlloc... 
it's all there.

On Sunday, April 18, 2021 at 12:33:20 PM UTC-5 Trig wrote:

> Correct... the example using time.Sleep didn't run on the playground.  The 
> original post I made, I provided the link with just a goroutine with an 
> empty function.
>
> At least you were able to reproduce what I'm inquiring about.  I'll look 
> further into this, but surely unused and finished goroutines don't leave 
> stuff laying around like that.
>
> On Sunday, April 18, 2021 at 3:47:10 AM UTC-5 Brian Candler wrote:
>
>> What do you mean by "It won't work on the playground"?  It runs for me.  
>> Are you saying you get different results when running locally?  If so, what 
>> version of go are you running locally, on what platform, and what do you 
>> see?
>>
>> Or are you saying the problem is really with something like this?
>> https://play.golang.org/p/Q91Qd-DvvKx
>>
>> That indeed fails to run in the playground - it exits with signal 9 
>> (128+9=137)
>>
>> Running locally with go 1.16.3 under macOS (Intel) I see:
>>
>> Allocs before: 82696
>> Allocs while running: 51496728
>> Allocs after: 40384112
>> Allocs after: 40384112
>> Allocs after: 40384112
>> Allocs after: 40384112
>> Allocs after: 40384112
>>
>> That is 40MB that apparently isn't reclaimed, but it does get reused if 
>> you run more goroutines:
>> https://play.golang.org/p/YcMTlLYxXAP
>>
>> I don't know why that is.  It's about 400 bytes per goroutine.  Stack 
>> perhaps?
>>
>

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[go-nuts] Re: go routines not being deallocated

[Trig]

Correct... the example using time.Sleep didn't run on the playground.  The 
original post I made, I provided the link with just a goroutine with an 
empty function.

At least you were able to reproduce what I'm inquiring about.  I'll look 
further into this, but surely unused and finished goroutines don't leave 
stuff laying around like that.

On Sunday, April 18, 2021 at 3:47:10 AM UTC-5 Brian Candler wrote:

> What do you mean by "It won't work on the playground"?  It runs for me.  
> Are you saying you get different results when running locally?  If so, what 
> version of go are you running locally, on what platform, and what do you 
> see?
>
> Or are you saying the problem is really with something like this?
> https://play.golang.org/p/Q91Qd-DvvKx
>
> That indeed fails to run in the playground - it exits with signal 9 
> (128+9=137)
>
> Running locally with go 1.16.3 under macOS (Intel) I see:
>
> Allocs before: 82696
> Allocs while running: 51496728
> Allocs after: 40384112
> Allocs after: 40384112
> Allocs after: 40384112
> Allocs after: 40384112
> Allocs after: 40384112
>
> That is 40MB that apparently isn't reclaimed, but it does get reused if 
> you run more goroutines:
> https://play.golang.org/p/YcMTlLYxXAP
>
> I don't know why that is.  It's about 400 bytes per goroutine.  Stack 
> perhaps?
>

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[go-nuts] Re: go routines not being deallocated

[Trig]

Sorry, for clarification... the above should be, if you 'put something like 
time.Sleep(time.Second * 1) *in the go routine*...'

On Sunday, April 18, 2021 at 12:32:39 AM UTC-5 Trig wrote:

> Can somebody tell me why this is?  It won't work on the playground; 
> however, put something like time.Sleep(time.Second * 1) and put the last 
> allocs in a loop... and you'll see it's literally MBs of Allocs used that 
> never get released.
>
> What am I doing wrong, or not understanding here?  I thought go routines 
> got completely removed after they've returned (assuming they're not blocked 
> from doing so).
>
> https://play.golang.org/p/JfaOVnpMUpf
>

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[go-nuts] go routines not being deallocated

[Trig]

Can somebody tell me why this is?  It won't work on the playground; 
however, put something like time.Sleep(time.Second * 1) and put the last 
allocs in a loop... and you'll see it's literally MBs of Allocs used that 
never get released.

What am I doing wrong, or not understanding here?  I thought go routines 
got completely removed after they've returned (assuming they're not blocked 
from doing so).

https://play.golang.org/p/JfaOVnpMUpf

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[go-nuts] Grouped functions...

[Trig]

So, in Go... you can either define imports, constants, types, variables one 
at a time... or you can group them using brackets.  Why was it decided not 
to be able to do that with functions?  Just curious.

func (
 main() {
fmt.Println(helloWorld())
 }

 helloWorld() string {
return "hello, world..."
 }
)

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[go-nuts] Structs for JSON APIs and required fields... using pointers

[Trig]

What is the standard practice between required fields of a struct you're 
expecting to deserialize using JSON, and using pointers for this (if 
there's any correlation)?

API defined a string as required.  Do you define it as a string and check 
for zero-value for that type, or *string and check for nil, etc.?  Any 
other situations/instances were it's best practice to user a pointer for 
defining struct fields over the standard type?

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[go-nuts] go module name

[Trig]

Is there a way to get the go module name out of the go mod, if modules 
used, besides opening the go.mod file directly (or another obvious name to 
get the project name I'm not thinking of)?

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Re: [go-nuts] Assignment of pointer values in a struct...

[Trig]

And I did it again... posted from another gmail account by accident, and my 
post is forever in 'approval status', lol.  Basically what Robert here said.

On Thursday, June 4, 2020 at 9:53:56 AM UTC-5, Robert Engels wrote:
>
> You need pointers to strings if you need a nil value to be represented 
> which is often the case in databases. 
>
> > On Jun 4, 2020, at 9:30 AM, Saksham Saxena  > wrote: 
> > 
> > Yep perfectly fine. MongoDB Driver for Go also uses such a wrapper at 
> many places where it takes a string as an argument and returns a pointer to 
> it which is required internally. Not really sure why use a pointer to 
> strings in Go because they're immutable, but I guess to reach their own. 
> > 
> > -- 
> > You received this message because you are subscribed to the Google 
> Groups "golang-nuts" group. 
> > To unsubscribe from this group and stop receiving emails from it, send 
> an email to golan...@googlegroups.com . 
> > To view this discussion on the web visit 
> https://groups.google.com/d/msgid/golang-nuts/17f2c250-ea5f-41fc-ac1b-0890a69f593b%40googlegroups.com.
>  
>
>
>

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[go-nuts] Assignment of pointer values in a struct...

[Trig]

I posted this question the other day and don't see it (may have posted from 
another gmail account and it's still pending approval)... so here I am 
again.

Let's say I have something like below:
type (
   Person struct {
  FirstName *string
   }
)

Usually, I see something like the following when assigning:
fn := "John"
_ = Person{
  FirstName: ,
}

Would something like the following be alright and acceptable practice:
_ = Person{
  FirstName: pString("John")
}


func pString(content string) *string {
   return 
}

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Re: [go-nuts] getting values from memory addresses within another process...

[Trig]

Kurtis,

   Thanks... that 'Cheat Engine' is the correct one.  Basically, what I am 
doing is creating a simple service that watches for a particular process (a 
game, in this instance) and 'monitors' certain values (such as life levels, 
mana levels, etc.).  If my health in the game is low, it simply plays an 
audio file that let's me know to drink a potion, etc.  I'm not needing to 
write any values to memory (like a bot would actually do)... just be able 
to read them.

On Thursday, April 30, 2020 at 10:43:50 PM UTC-5, Kurtis Rader wrote:
>
> On Thu, Apr 30, 2020 at 8:25 PM Eric Brown > 
> wrote:
>
>> I’ll look into this solution.  Thank you for an answer that points me in 
>> a possible direction.
>>
>
> Gah! I hit the "send" button without providing any useful response in my 
> previous reply. Note that reading /proc/$pid/mem is only applicable to 
> Linux. And that solution basically requires your program, written in Go, to 
> be run as root.
>
> You need to provide more information about what you're trying to do. 
> Including any relevant constraints such as particular operating systems you 
> want to support. You also referenced "Cheat Engine" without providing a 
> link to a document that explains what you mean by that term. I'm guessing 
> (emphasis on "guessing") that you are referring to 
> https://en.wikipedia.org/wiki/Cheat_Engine
>
> --
> Kurtis Rader
> Caretaker of the exceptional canines Junior and Hank
>

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[go-nuts] getting values from memory addresses within another process...

[Trig]

I'm attempting to read memory from another process.  I've installed 'Cheat 
Engine' to do this, to make sure I'm pulling the correct value from the 
address I'm attempting to; however, nothing I found works  I did find this 
article:

https://stackoverflow.com/questions/37358478/read-random-memory-locations-with-golang

I don't believe that is correct though, as using the address of the 
location I'm attempting to read doesn't result in a value anywhere near 
what 'Cheat Engine' is reporting.  I've looked at the 'unsafe' and 
'syscall' packages; however, there's very little information on them.  
Also, searched many ways trying to find examples on how to do this.  I'm on 
a Mac (and use Linux).  On Windows, I can do this fairly easy.  I can't 
seem to find anything that works (not experienced at all in syscalls) for 
linux or darwin platforms.  Any help appreciated.

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[go-nuts] Re: Need help with VSCode, GOPATH and intellisense

[Trig]

I only got mine working 99% of the time with a language server configured 
in my settings:

{
"go.useLanguageServer": true,
"go.languageServerExperimentalFeatures": {
"diagnostics": true // for diagnostics as you type
},
"[go]": {
"editor.snippetSuggestions": "none",
"editor.formatOnSave": true,
"editor.codeActionsOnSave": {
"source.organizeImports": true
},
},
"gopls": {
"usePlaceholders": true, // add parameter placeholders when completing a 
function
"enhancedHover": true, // experimental to improve quality of hover (will be 
on by default soon)
},
"eslint.autoFixOnSave": true,
"prettier.eslintIntegration": true
}


On Tuesday, May 28, 2019 at 5:32:51 AM UTC-5, Subramanian Sridharan wrote:
>
> I cannot use intellisense and have my own source packages be recognized at 
> the same time.
>
> Golang Server - ON
> Infer GOPATH from root - False
> GOPATH - Empty
> Result - I get details on hover. But my own source package imports fail.
>
> Golang Server - ON
> Infer GOPATH from root - True
> GOPATH - Empty
> Result - Source package imports don't show error. No information on hover.
>
> Golang Server - ON
> Infer GOPATH from root - False
> GOPATH - ~/go:~/dc_native   // The src is actually in ~/dc_native/x/y/
> Result - I get details on hover. But my own source package imports fail.
>
> Golang Server - ON
> Infer GOPATH from root - False
> GOPATH - ~/go:~dc_native/x/y  // Inside which src containing own source 
> packages are present.
> Result - Source package imports don't show error. No information on hover.
>
> At some point, intellisense was working where I was able to get 
> suggestions for structure members from another file of the same package.
> I can't get that to work now.
>
> Where am I going wrong?
>
> PS: The GOPATH paths are actually absolute and not relative.
>
>
>

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[go-nuts] Re: How to constant ?!

[Trig]

Whoops... forgot to add the top line to the code syntax.  I really wish you 
could edit existing posts in this group.

On Tuesday, May 28, 2019 at 10:03:05 AM UTC-5, Trig wrote:
>
> package main
>
> import "fmt"
>
> const (
>  ExposedConstant  = "1"  // exposed outside of package
>  internalConstant = "2"  // for use anywhere in package only
> )
>
> func main() {
>  const functionConstant = "3"  // usable anywhere in main func
>
>  fmt.Println(ExposedConstant, internalConstant, functionConstant)
> }
>
>
>
> On Tuesday, May 28, 2019 at 7:12:06 AM UTC-5, Ashutosh Baghel wrote:
>>
>> Hello folks,
>>
>> I want to declare a few variables constant. But I guess there is nothing 
>> as "Constant" type in GoLang. How do I achieve this in GoLang?
>>
>

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[go-nuts] Re: How to constant ?!

[Trig]

package main

import "fmt"

const (
 ExposedConstant  = "1"  // exposed outside of package
 internalConstant = "2"  // for use anywhere in package only
)

func main() {
 const functionConstant = "3"  // usable anywhere in main func

 fmt.Println(ExposedConstant, internalConstant, functionConstant)
}



On Tuesday, May 28, 2019 at 7:12:06 AM UTC-5, Ashutosh Baghel wrote:
>
> Hello folks,
>
> I want to declare a few variables constant. But I guess there is nothing 
> as "Constant" type in GoLang. How do I achieve this in GoLang?
>

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[go-nuts] Is this possible in Go, and if so how would one do it?

[Trig]

So, I'm creating a package for my service.  Let's say I have multiple 
versions with different features depending on the version and authorization 
type specified, such as:

Authorization Type: ThirdParty
Version: 1.0
Utilizes: HMAC_SHA1 hash digest

Authorization Type: ThirdParty
Version: 1.1
Utilizes: HMAC_SHA1 or HMAC_SHA256 hash digest

Authorization Type: Internal
Version: 1.0
Utilized: HMAC_SHA512

I'm wanting to construct a configuration setting where the developer using 
it can set the configuration in a chain, similar to:

MyPackage.Initialize(MyPackage.ThirdParty.Version10.HMAC_SHA1)

Using intellisense (and using ThirdParty authorization for the example), I 
only want HMAC_SHA1 to appear if Version10 is specified, and both HMAC_SHA1 
and HMAC_SHA256 to appear as options if Version11 in specified in the 
chain.  How would one go about setting this up?  I've attempted different 
strategies utilizing defined types, type functions, etc. and just can't get 
it to work.  Think of it as a treeview.  Each section you define only has 
options available under that specific view... and propagates all the way 
down the tree.  Something like this would be awesome:

package MyPackage

tree (
 ThirdParty {
  Version10 {
   HMAC_SHA1 string = "thirdPartyVersion10HmacSha1"
  }
  Version11 {
   HMAC_SHA1 string = "thirdPartyVersion11HmacSha1"
   HMAC_SHA256 string = "thirdPartyVersion11HmacSha256"
  }
 }
 Internal {
  Version10 {
   HMAC_SHA512 string = "internalVersion10HmacSha512"
  {
 {
}



Where the IDE would know to populate intellisense down those paths to the 
ending defined type (e.g. 
fmt.Print(MyPackage.ThirdParty.Version11.HMAC_SHA256) would result in 
"thirdPartyVersion11HmacSha256" being printed)... and the IDE would 
interpret that and make a map out of it internally or something.  Anyhow, 
hopefully that gives you an idea of what I'm trying to accomplish.  Any 
suggestions would be appreciated!  Thanks...

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Re: [go-nuts] Trouble with exiting a for loop that contains bufio.NewScanner.Scan()

[Trig]

When reading from a serial port, there is no EOF between data sets.  I may 
have to use something else besides a scanner to do this.  I have a handler 
function called by a goroutine that just monitors incoming data in a for 
loop and sends that data coming in back through a channel.  If the 
connection closes, I need a way to signal this loop to close so that the 
function can return and end.

On Sunday, December 30, 2018 at 6:48:21 PM UTC-6, Wagner Riffel wrote:
>
> Scan() returns false when it reaches EOF or an error, so with what you 
> provided i assume you're missing to check that. 
> for ns.Scan() { 
> ... 
> } 
>
> or 
>
> for { 
> if !ns.Scan() { 
> break 
> } 
>
> -wgr 
>
> On Sun, Dec 30, 2018 at 10:36 PM Trig > 
> wrote: 
> > 
> > I'm currently utilizing the bufio.NewScanner to read ASCII data from a 
> serial port.  I have the following simple code: 
> > 
> > ns := bufio.NewScanner(sPort) 
> > 
> > for { 
> >ns.Scan() 
> >if ns.Text() != "" { // ignore blank lines 
> >   // handle content here 
> >} 
> > } 
> > 
> > The problem is ns.Scan() blocks the loop from continuing if there isn't 
> any data.  This leaves me unable to break out of the loop with a for 
> condition or a select statement also within the loop which is looking for a 
> close command from a channel before or after it, etc.  Am I doing something 
> wrong, or is there a proper way to handle this? 
> > 
> > -- 
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>

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[go-nuts] Trouble with exiting a for loop that contains bufio.NewScanner.Scan()

[Trig]

I'm currently utilizing the bufio.NewScanner to read ASCII data from a 
serial port.  I have the following simple code:

ns := bufio.NewScanner(sPort)

for {
   ns.Scan()
   if ns.Text() != "" { // ignore blank lines
  // handle content here
   }
}

The problem is ns.Scan() blocks the loop from continuing if there isn't any 
data.  This leaves me unable to break out of the loop with a for condition 
or a select statement also within the loop which is looking for a close 
command from a channel before or after it, etc.  Am I doing something 
wrong, or is there a proper way to handle this?

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[go-nuts] Re: go1.11.4.windows-amd64.zip not downloading...

[Trig]

On Thursday, December 20, 2018 at 2:11:59 PM UTC-6, Trig wrote:
>
> Is anybody able to successfully download from this link?  All other 
> platforms/versions appear to work... just this one isn't doing anything for 
> me.
>
> https://golang.org/doc/install?download=go1.11.4.windows-amd64.zip
>

I take that back.  All appear to be working, but it just sits at 0 bytes 
downloaded and does nothing.  If you cancel the download and try again, you 
never even get the download dialog that usually pops up. 

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[go-nuts] go1.11.4.windows-amd64.zip not downloading...

[Trig]

Is anybody able to successfully download from this link?  All other 
platforms/versions appear to work... just this one isn't doing anything for 
me.

https://golang.org/doc/install?download=go1.11.4.windows-amd64.zip

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[go-nuts] timeout with bufio.Scanner & Scanner.Scan()

[Trig]

I'm currently reading ASCII data from a serial port using the bufio.Scanner 
(since what's coming back is a line at a time, it's convenient w/ reading 
using the Scanner.Text()).  Problem is, the for loop I use to process the 
reads lock at the Scanner.Scan() call.  Is there a to implement some for 
loop that utilized the scanner while utilizing a timeout?

I've tried:

for {
   select {
  case <- time.After(time.Second * 3):
 response <- {
Error: fmt.Errorf("command call took to long for a response"),
 }

 break
  default:
 myScanner.Scan()

 if myScanner.Text() == "OK" {
response <- {
   Content: []responseLines,
}

break
 }
  
 responseLines = append(responseLines, myScanner.Text())
   }
}

Of course, after looking at it... it makes sense why it's not working as 
the loop locks at myScanner.Scan() if there is nothing further to Scan.  
Any help or examples would be appreciated.

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[go-nuts] Using reflect to utilized the call to gob.Register()?

[Trig]

Is it possible, somehow, to use reflection to utilize the call to 
gob.Register()?  Something like:

gob.Register(m.Type().In(0))

Problem I'm having is that m.Type().In(0) is a type of *reflect.rtype, so 
it registers that... and not the actual type being reflected.

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[go-nuts] Windows 10 x64 - the program can't start because libz-1.dll is missing from your computer.

[Trig]

Compiled a small app w/ Go 1.11 and only used one 3rd-party import 
("github.com/go-vgo/robotgo").  GOARCH=amd64; GOOS=windows.  Runs fine on 
the computer I used to build it.  I copy it in a VMWARE instance of Windows 
10 x64, and I get that 'libz-1.dll' is missing from your computer when I 
try to execute it.  I thought go binaries contained everything needed to 
run itself, assuming the platforms for compiling and executing matched?  
Anybody have any ideas what's going on, and why this happened?

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[go-nuts] Re: Any interest for an online "Go programming" degree ?

[Trig]

There are already so many good courses available out there, and most 
employers either do white-boarding, a coding challenge, or want to see some 
existing code on a public repo such as Github.com.  So, IMHO... even with a 
'certificate' or 'degree', that would likely not change these 
requirements|requests from such employers.  They want to see whether you 
know your stuff, regardless of experience or schooling.  That's what 
matters in the end.

On Saturday, February 3, 2018 at 10:45:22 AM UTC-6, Sylvain wrote:
>
> Hi,
>
> I am now working as "head of code and design education" at the leading 
> Online Learning Company in France, operating from the heart of Paris.
>
> We offer government certified degrees (very important in France! employers 
> will offer you an interview depending on which degrees you put on your 
> resume, not what you can do :) )
>
> We do Java, PHP, Python, even Ruby... I would love to create a programming 
> degree based on Go - starting from scratch, so as to learn the good 
> practises from the beginning
>
> If you work at a company operating in France, use Go and struggle to hire 
> good programmers, I would love to hear from you so as to 
>
> 1) make a good case to justify the creation of this degree
> 2) make sure the learning objectives align with your needs
>
> Thanks for your time
>
> Sylvain
>

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Re: [go-nuts] Decoder.DisallowUnknownFields() works when passing *struct but not *map[string]interface{}

[Trig]

I dunno... it doesn't seem to satisfy this check, even though the article 
you sent me states maps are pointers (but does satisfy == reflect.Map).  
Doesn't the unmarshaller check for a pointer using == reflect.Ptr before it 
does anything?  I haven't looked at it lately (can't atm, so going on 
memory)... but I think it does.

https://play.golang.org/p/lX7P2FtRlMo

On Tuesday, January 30, 2018 at 9:29:09 AM UTC-6, Trig wrote:
>
> I guess it's not needed.  I know that the json unmarshaller requires a 
> pointer to a struct... so for consistency, I was just stating it as a 
> pointer.  I had no idea that make(map) returns *hmap.
>
> On Tuesday, January 30, 2018 at 9:13:28 AM UTC-6, matthe...@gmail.com 
> wrote:
>>
>> Dave talks about map representation here: 
>> https://dave.cheney.net/2017/04/30/if-a-map-isnt-a-reference-variable-what-is-it
>>
>> I don’t understand why you need a pointer to a map, can you provide a 
>> code example?
>>
>> Matt
>>
>> On Tuesday, January 30, 2018 at 8:22:54 AM UTC-6, Trig wrote:
>>>
>>> Appreciate the response.  I'm wanting to pass a *map[string]interface{} 
>>> where the keys (strings) are already populated.  I'm thinking of just 
>>> creating a func which does this itself... checks to see if the keys exists 
>>> and populate accordingly, and if not... return an error.  Don't think this 
>>> will be too difficult; however, would be a nice feature to discuss about 
>>> being implemented into the json standard library.
>>>
>>> On Tuesday, January 30, 2018 at 5:31:01 AM UTC-6, Konstantin Khomoutov 
>>> wrote:
>>>>
>>>> On Sun, Jan 28, 2018 at 10:59:58AM -0800, Trig wrote: 
>>>>
>>>> > This works as intended when you pass it a pointer to a Struct; 
>>>> however, it 
>>>> > should also work (you would think, since the Unmarshaller can handle 
>>>> both 
>>>> > types) a pointer to a *map[string]interface{}; however, it does not. 
>>>>  Are 
>>>> > there any future plans to implement this option on both types? 
>>>>
>>>> You're talking about [1], are you? 
>>>>
>>>> If yes, the commit [2] which closed it specifically talks about struct 
>>>> types, so the function behaves as documented. 
>>>>
>>>> On the other hand, I have two questions to narrow the scope of your 
>>>> claim down. 
>>>>
>>>>  - To carry out its intended task, DisallowUnknownFields() has to 
>>>> operate 
>>>>on a value which it can use to figure out the set of known fields. 
>>>>
>>>>In the case of a map this suggests that the map passed to that 
>>>> method 
>>>>must be populated with the keys which would define the names of 
>>>>the known fields (and the values assigned to those keys are expected 
>>>>to be overwritten by the decoding process). Is this what you're 
>>>> proposing? 
>>>>
>>>>  - Why a pointer to a map? 
>>>>
>>>>In my eyes, this suggests that you may legitimately pass a pointer 
>>>>to an unitialized map value and expect the decoder to create one for 
>>>>you; is that correct? 
>>>>
>>>>If "yes" is the answer to the both points, they cannot be satisfied 
>>>>together: to fulfill the first requirement the map value must be 
>>>> non-nil, 
>>>>and you cannot expect the decoder to initialize it for you. 
>>>>
>>>> All in all, I suggest you to create a proposal in the issue tracker. 
>>>> Just be sure to be crystal clear, when laying it out -- to save the 
>>>> devs 
>>>> from guessing what you really meant. 
>>>>
>>>> 1. https://github.com/golang/go/issues/15314 
>>>> 2. 
>>>> https://github.com/golang/go/commit/2596a0c075aeddec571cd658f748ac7a712a2b69
>>>>  
>>>>
>>>>

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Re: [go-nuts] Decoder.DisallowUnknownFields() works when passing *struct but not *map[string]interface{}

[Trig]

I guess it's not needed.  I know that the json unmarshaller requires a 
pointer to a struct... so for consistency, I was just stating it as a 
pointer.  I had no idea that make(map) returns *hmap.

On Tuesday, January 30, 2018 at 9:13:28 AM UTC-6, matthe...@gmail.com wrote:
>
> Dave talks about map representation here: 
> https://dave.cheney.net/2017/04/30/if-a-map-isnt-a-reference-variable-what-is-it
>
> I don’t understand why you need a pointer to a map, can you provide a code 
> example?
>
> Matt
>
> On Tuesday, January 30, 2018 at 8:22:54 AM UTC-6, Trig wrote:
>>
>> Appreciate the response.  I'm wanting to pass a *map[string]interface{} 
>> where the keys (strings) are already populated.  I'm thinking of just 
>> creating a func which does this itself... checks to see if the keys exists 
>> and populate accordingly, and if not... return an error.  Don't think this 
>> will be too difficult; however, would be a nice feature to discuss about 
>> being implemented into the json standard library.
>>
>> On Tuesday, January 30, 2018 at 5:31:01 AM UTC-6, Konstantin Khomoutov 
>> wrote:
>>>
>>> On Sun, Jan 28, 2018 at 10:59:58AM -0800, Trig wrote: 
>>>
>>> > This works as intended when you pass it a pointer to a Struct; 
>>> however, it 
>>> > should also work (you would think, since the Unmarshaller can handle 
>>> both 
>>> > types) a pointer to a *map[string]interface{}; however, it does not. 
>>>  Are 
>>> > there any future plans to implement this option on both types? 
>>>
>>> You're talking about [1], are you? 
>>>
>>> If yes, the commit [2] which closed it specifically talks about struct 
>>> types, so the function behaves as documented. 
>>>
>>> On the other hand, I have two questions to narrow the scope of your 
>>> claim down. 
>>>
>>>  - To carry out its intended task, DisallowUnknownFields() has to 
>>> operate 
>>>on a value which it can use to figure out the set of known fields. 
>>>
>>>In the case of a map this suggests that the map passed to that method 
>>>must be populated with the keys which would define the names of 
>>>the known fields (and the values assigned to those keys are expected 
>>>to be overwritten by the decoding process). Is this what you're 
>>> proposing? 
>>>
>>>  - Why a pointer to a map? 
>>>
>>>In my eyes, this suggests that you may legitimately pass a pointer 
>>>to an unitialized map value and expect the decoder to create one for 
>>>you; is that correct? 
>>>
>>>If "yes" is the answer to the both points, they cannot be satisfied 
>>>together: to fulfill the first requirement the map value must be 
>>> non-nil, 
>>>and you cannot expect the decoder to initialize it for you. 
>>>
>>> All in all, I suggest you to create a proposal in the issue tracker. 
>>> Just be sure to be crystal clear, when laying it out -- to save the devs 
>>> from guessing what you really meant. 
>>>
>>> 1. https://github.com/golang/go/issues/15314 
>>> 2. 
>>> https://github.com/golang/go/commit/2596a0c075aeddec571cd658f748ac7a712a2b69
>>>  
>>>
>>>

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Re: [go-nuts] Decoder.DisallowUnknownFields() works when passing *struct but not *map[string]interface{}

[Trig]

Appreciate the response.  I'm wanting to pass a *map[string]interface{} 
where the keys (strings) are already populated.  I'm thinking of just 
creating a func which does this itself... checks to see if the keys exists 
and populate accordingly, and if not... return an error.  Don't think this 
will be too difficult; however, would be a nice feature to discuss about 
being implemented into the json standard library.

On Tuesday, January 30, 2018 at 5:31:01 AM UTC-6, Konstantin Khomoutov 
wrote:
>
> On Sun, Jan 28, 2018 at 10:59:58AM -0800, Trig wrote: 
>
> > This works as intended when you pass it a pointer to a Struct; however, 
> it 
> > should also work (you would think, since the Unmarshaller can handle 
> both 
> > types) a pointer to a *map[string]interface{}; however, it does not. 
>  Are 
> > there any future plans to implement this option on both types? 
>
> You're talking about [1], are you? 
>
> If yes, the commit [2] which closed it specifically talks about struct 
> types, so the function behaves as documented. 
>
> On the other hand, I have two questions to narrow the scope of your 
> claim down. 
>
>  - To carry out its intended task, DisallowUnknownFields() has to operate 
>on a value which it can use to figure out the set of known fields. 
>
>In the case of a map this suggests that the map passed to that method 
>must be populated with the keys which would define the names of 
>the known fields (and the values assigned to those keys are expected 
>to be overwritten by the decoding process). Is this what you're 
> proposing? 
>
>  - Why a pointer to a map? 
>
>In my eyes, this suggests that you may legitimately pass a pointer 
>to an unitialized map value and expect the decoder to create one for 
>you; is that correct? 
>
>If "yes" is the answer to the both points, they cannot be satisfied 
>together: to fulfill the first requirement the map value must be 
> non-nil, 
>and you cannot expect the decoder to initialize it for you. 
>
> All in all, I suggest you to create a proposal in the issue tracker. 
> Just be sure to be crystal clear, when laying it out -- to save the devs 
> from guessing what you really meant. 
>
> 1. https://github.com/golang/go/issues/15314 
> 2. 
> https://github.com/golang/go/commit/2596a0c075aeddec571cd658f748ac7a712a2b69 
>
>

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Re: [go-nuts] Why []Interface{} indexing failing at if statement

[Trig]

Actually, Jan's way is probably the best... as if you wrongfully type 
convert the wrong type, it'll panic (you'll need to know for sure that arr 
in this instance will always be a boolean).  With Jan's way, you're just 
making a comparison of value... which will work regardless of the type.

On Monday, January 29, 2018 at 1:52:38 PM UTC-6, Trig wrote:
>
> This... or just specify the type after 'arr' such as:
>
> if arr.(bool) {
> fmt.Println("This is a boolean value")
> }
>
>
> On Monday, January 29, 2018 at 5:41:17 AM UTC-6, Jan Mercl wrote:
>>
>> On Mon, Jan 29, 2018 at 12:36 PM pradam <pradam.pr...@gmail.com> wrote:
>>
>> > //here its throwing error like: non-boolean condition in if statement
>>
>> The compiler is right. 'arr' is not a boolean expresion, its type is 
>> 'interface{}'. Try: https://play.golang.org/p/zwNV9RD2oCs.
>>
>> -- 
>>
>> -j
>>
>

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Re: [go-nuts] Why []Interface{} indexing failing at if statement

[Trig]

This... or just specify the type after 'arr' such as:

if arr.(bool) {
fmt.Println("This is a boolean value")
}


On Monday, January 29, 2018 at 5:41:17 AM UTC-6, Jan Mercl wrote:
>
> On Mon, Jan 29, 2018 at 12:36 PM pradam  > wrote:
>
> > //here its throwing error like: non-boolean condition in if statement
>
> The compiler is right. 'arr' is not a boolean expresion, its type is 
> 'interface{}'. Try: https://play.golang.org/p/zwNV9RD2oCs.
>
> -- 
>
> -j
>

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[go-nuts] Re: best package for serial port io access in golang?

[Trig]

I've only used https://github.com/tarm/serial and it hasn't let me down 
yet.  It's simple and light-weight... does its job.  Nothing more... 
nothing less.

On Sunday, January 28, 2018 at 1:54:05 PM UTC-6, John Moore wrote:
>
> Hi,
>   I need to talk to external devices with serial (probably just over a USB 
> dongle), and do it from both Windows and Mac.
>
>   I see a few libraries out there but little talk about this.
>
>   Is anyone doing serial work with golang these days? Are there best 
> libraries? If so, can one avoid hanging forever waiting to receive data 
> that will never arrive?
>
> John
>

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[go-nuts] Decoder.DisallowUnknownFields() works when passing *struct but not *map[string]interface{}

[Trig]

This works as intended when you pass it a pointer to a Struct; however, it 
should also work (you would think, since the Unmarshaller can handle both 
types) a pointer to a *map[string]interface{}; however, it does not.  Are 
there any future plans to implement this option on both types?

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[go-nuts] json struct tag

[Trig]

I've searched but can't find any good sources on json struct tag options 
and rules...

Does the order in which the options in the tag appear matter (e.g. 
`json:"first_name,omitempty"` vs `json:"omitempty,first_name"`) ?

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[go-nuts] is this safe?

[Trig]

 for i, user := range myList {
 if user.Disabled { 
  myList = append(myList[:i], myList[i + 1:]...) // remove user from return 
list 
 } 
}


Is using append this way (to remove an index), inside of the range loop of 
the same array I'm working with, safe... since the size of myList is being 
changed within it?

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[go-nuts] Re: Why is there a difference between floating-point multiplication with literals vs. variables in Go?

[Trig]

There are 3rd-party packages/vendors that help with this, such as:

https://github.com/shopspring/decimal

On Thursday, November 9, 2017 at 5:36:03 PM UTC-6, Erik Swan wrote:
>
> Why are the following unequal in Go? Is this a bug, or is it by design? If 
> it's by design, why does this occur and is this type of behavior documented 
> anywhere?
>
> https://play.golang.org/p/itEV9zwV2a
>
> package main
>
> import (
> "fmt"
> )
>
> func main() {
> x := 10.1
>
> fmt.Println("x == 10.1:", x == 10.1)
> fmt.Println("x*3.0 == 10.1*3.0:", x*3.0 == 10.1*3.0)
> fmt.Println("x*3.0:", x*3.0)
> fmt.Println("10.1*3.0: ", 10.1*3.0)
> }
>
> Produces:
>
> x == 10.1: true
> x*3.0 == 10.1*3.0: false
> x*3.0: 30.297
> 10.1*3.0:  30.3
>
>
>

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[go-nuts] interface{} as type []interface{}

[Trig]

Is it possible to have an interface{} as type []interface{}?

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Re: [go-nuts] Get method/function parameter types with reflect?

[Trig]

Thank you!  You lead me in the right direction.  It was .In() and .Out() I 
was looking for.  Appreciate it, Ian.

On Thursday, October 12, 2017 at 6:12:41 PM UTC-5, Ian Lance Taylor wrote:
>
> On Thu, Oct 12, 2017 at 3:03 PM, burpswangy  > wrote: 
> > 
> > Is it possible to use the reflect package to get the parameter/function 
> > types for a specified method/function? 
>
> I'm not sure precisely what you are asking, but the answer is probably 
> yes.  Start with something like reflect.ValueOf(myFunction).Type(). 
>
> Ian 
>

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