theritikchoure / golang-learning

Go lang learning

Advantages of Go lang

• Code runs fast
• Garbage collection
• Simpler objects
• Concurrency is efficient

###= Software Translation

• Machine Language : CPU instructions represented in binary
• Assembly Language : CPU instructions with mnemonics
  • Easier to read
  • Equivalent to machine language
• High Level Language : Commonly used languages (C, C++, Java, Python, Go)
  • Much easier to use

All software must be translated into the machine language of processors

Compiled vs Interpreted

• Compilation : Translate instructions once before running the code

  • C, C++, Java (partially)
  • Translation occurs only once, saves time

• Interpretation : Translate instructions while code is executed

  • Python, Java (partially)
  • Translation occurs every execution
  • Requires an interpreter

Efficiency vs Ease-of-Use

• Compiled code is fast

• Interpreters make coding easier

  • Manage memory automatically
  • Infer variable types

• Go is a good compromise

Garbage Collection

• Automatic memory management

  • where should memory be allocated?
  • when can memory be deallocated?

• Manual memory management is hard

  • Deallocate too early, false memory access
  • Deallocate too late, wasted memory

Go includes garbage collection

• Typically only done by interpreters

Object-Oriented Programming

• Organize your code through encapsulation
• Group together data and functions which are related
• User-defined type which is specific to an application

Objects in Go

• Go does not use the term class
• Go uses structs with associated methods
• Simplified implementation of classes
  • No inheritance
  • No constructor
  • No generics

Performance limits

• Moore's law used to help performance

  • Number of transistors doubles every 18 months

• More transistors used to lead to higher clock frequencies

• Power/temperature constraints limit clock frequencies now

Parallelism

• Number of cores still increases over time

• Multiple tasks may be performed at same time on different cores

• Difficulties with parallelism

  • when do tasks start/stop?
  • What if one task need data from another task?
  • do tasks conflict in memory?

Concurrent programming

• Concurrency is the mngmt of multiple tasks at the same time
• Key requirements of large systems
• Concurrent programming enables parallelism
  • Management of task execution
  • Communication between tasks
  • Synchronization between tasks

Concurrency in GO

• Go includes concurrency primitives
• Goroutines represent concurrent tasks
• Channels are used to communicate between tasks
• Select enable task synchronization
• Concurrency primitives are efficient and easy to use

Variables

• Data stored in memory
• Must have a name and a type
• All variables must have declarations
• Most basic variable declaration

                var       x       int
                /         |         \
               /          |          \
           keyword      name        type

• Can declare many on the same line var x, y int

Variable types

• Types define the values a variable may take and operations that can be performed on it.

• Integer

  • Integral values
  • Integer arithmetic (+, -, *, /, ...)

• Floating point

  • Fractional (decimal) values
  • Floating point arithmetic (may use different hardware)

• Strings

  • Byte (character) sequences
  • String comparison, search ...

Pointers

• A pointer is an address to data in memory
• & operator returns the address of a variable/function
• * operator returns data at an address(dereferencing)

var x int = 1
var y int
var ip *int // ip is a pointer to int

ip = &x // ip now points to x

y = *ip // y is now 1

New

• Alternate way to create a new variable
• new() function creates a variable and returns a pointer to the variable
• variable is initialized to zero

  ptr = new(int)
  *ptr = 3