go lang beginner's workshop

8/10/2019 Go Lang Beginner's Workshop

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Go Lang Beginner's

WorkshopSathish VJ


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Download zip file at http://github.com/sathishvj/golang-workshops

Contains slides and thesource code Join our Google+ Community at http://goo.

gl/kwcxa Twitter hashtag: #golang My tutorials (oldish): http://golangtutorials.

blogspot.com Google Groupsgolang-nuts: https://groups.

google.com/forum/?fromgroups#!forum/golang-nuts

SublimeText users, try GoSublimeplugin

Starting off ...
https://groups.google.com/forum/?fromgroups#!forum/golang-nutshttps://groups.google.com/forum/?fromgroups#!forum/golang-nutshttps://groups.google.com/forum/?fromgroups#!forum/golang-nutshttp://golangtutorials.blogspot.com/http://goo.gl/kwcxahttp://github.com/sathishvj/golang-workshopshttp://github.com/sathishvj/golang-workshopshttp://github.com/sathishvj/golang-workshopshttps://groups.google.com/forum/?fromgroups#!forum/golang-nutshttps://groups.google.com/forum/?fromgroups#!forum/golang-nutshttps://groups.google.com/forum/?fromgroups#!forum/golang-nutshttps://groups.google.com/forum/?fromgroups#!forum/golang-nutshttp://golangtutorials.blogspot.com/http://golangtutorials.blogspot.com/http://goo.gl/kwcxahttp://goo.gl/kwcxahttp://github.com/sathishvj/golang-workshopshttp://github.com/sathishvj/golang-workshops


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Download zip file for your platform Downloads: https://code.google.com/p/go/downloads/list

Extract it to a known location, say [x]/golang You should now have [x]/golang/godirectory

Set PATHto [x]/golang/go/bin Check version on the command line with

go version

Set GOROOTto [x]/golang/go

Set GOPATHto [x]/golang/mygopath Will be useful later (not today) when installing external

packages with go get and go install

Ref:http://golang.org/doc/install

Installation
http://golang.org/doc/installhttp://golang.org/doc/installhttps://code.google.com/p/go/downloads/list


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Documentation

Documentation available at http://golang.org/pkg

Try go doc fmtor go doc regexp for

documentation on specific packages If I'm slowing down for others, entertain

yourself at http://tour.golang.org

To run documentation locally:godoc -http=:6060

Then access via browser at: http://localhost:6060


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1. Hello World

Use any editor.

Save as hw.go

Run it as go run hw.go


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Hello World

Programs (generally) start at this function signature.

Packages of functionality are 'imported'

All functionality in a package. The main program has to be in 'main'package.

Use dot notation to access package functions. Note capitalization of 'P' in Print. Notethat all package names are in small.

Notice capital "P". Try what happens with "fmt.println"


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Hello WorldNo semicolons

Functions/methods defined with "func" keyword

Note naming convention. Small readable, variables thatsound right


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Immediately observable benefits

Very fast building Compiled into native executable; real fast

execution Works equally well on multiple platforms No virtual machines and repeated VM

update reminders Clean, clear, concise code Familiar programming concepts


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Go addresses ...

Computers fast but software constructionslow.

Dependency analysis necessary for speed,

safety. Types get in the way too much. Garbage collection, concurrency poorly

supported. Multi-core seen as crisis not opportunity.


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2. Variables


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Variables

Inverse of other ways of declaration. C/Java - int i = 10

Default/Zero values. String="", Int=0, Float=0.0, etc.

:= is definition and initialization

Println automatically formats data type for printing

Formatted prints with Printf

Arrays and how to initialize them


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3. Functions


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3. Functions

Function takes parameters in a similar format - name typeCombine many: (s1 string, s2 string, i int, j int) = (s1, s2 string, i, j int)

Awesomeness: Functions that are visible outside the package beginwith a capital letter.

You can also ignore return values with an underscore._ := Add(5, 10)


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3.5 Hello Web

Save as hweb.go

Run it as go run hweb.go

In your browser, go to http://localhost:8080


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Hello Web

can also be written as import ( "fmt" "net/http" ) //on separate lines

request datawrite your response into this

handler function follows the defined function signature: fun

HandleFunc(pattern string, handler func(ResponseWriter, *Requ

nil as empty value (not null)

Start built in server. No external server required!


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4. for loop


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4. for loop

For loop similar to Java, C(No parentheses though)

Infinite loop.(Can also give some parts). for i:=0;; { ... }

Use break to get out of current loop.Use continueto go to next loop index.


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5. struct and object representation


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5. struct and object representation

Use the type ... struct { }keywords

Member variable definitions

Initializing an empty struct instance. Default/zero values

assigned.

Assigning values to member variables in order of structdeclaration.

Use dot operator to access individual member variables.

Mix order or drop some variables with named variabledefinitions


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6. struct methods


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6. struct methods

Same dot notation to reach member methods.

Functions 'associated' with a type ... not physically inlexical scope of type.

Pointers automatically resolved ... note that acc()requires a pointer to aMyCar instance.


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7. multiple assignment,error handling


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multiple assignment,error handling

Package to use in converting to and from string

Multiple return values should be in parentheses

Accepting variables are in same order

The same multiple return value is used in an errorchecking paradigm. No try-catch.

"range" keyword gives a key, valuepair.For arrays, it is indexand value at indexFor maps (hashtables), it is key and value of key

Named return values possible

Eg. func f() (sum, prod int)


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8. Testing

Package to use in converting to and from string

Multiple return values should be in parentheses

Accepting variables are in same order

The same multiple return value is used in an error

checking paradigm

"range" keyword gives a key, valuepair.For arrays, it is indexand value at indexFor maps (hashtables), it is key and value of key

Named return values possible

Eg. func f() (sum, prod int)


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8. Testing

create dir

mymath save file as

add2.go

save file asadd2_test.go

go test


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8. Testing

Import package testingto run tests.

add2_test.go File has to end in_test.go

Test functions have to begin with Test_

Use a reference to *testing.Tin all tests. These

functions will be called by the testing framework.

Use functions Fatalf, Logf, Errorfto report teststatuses.


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Go is simple - minimal keywords, orthogonalconcepts, works as it is designed.

It's clean and easily readable. Readability leads to maintainability. Cross compilable to many platforms; code on X,

deploy on A, B, C, ... Z. Super fast in compilation and building.

Garbage collected. In-built web server - no additional server

installations needed.

A recap of early benefits


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Thank YouSathish VJ

Questions

go lang beginner's workshop

Documents