3 - Go Simple and Complex Variables

In last small sessions…

• we
• Had a small look on different IDEs (among-st them, gogland was the one which suits my requirements)
• Had an overview of program structure in golang
• Had a small description on which strategy should be followed for naming conventions for coding
• There is a blog which has all the standards mentioned… Link is provided in description:
• https://golang.org/doc/effective_go.html

Quick Recap

• Go files are stored with “.go” extension.
• There are two environment values which are required to run go-program
• GOROOT: The place where we will install golang (for example, C:\go)
• GOPATH: The place where we will work (for example, D:\workspace)
• Under GOPATH, we’ll have following structure
• GOPATH
• Src (This is where we will keep our work)
• Pkg (This is where go-framework will pull the package required for our work)
• Bin (This is where golang generates the final executable)
• Program structure: basic is
• Package name (mostly it is same as directory name)
• Import section
• Functions
• (The structure will grow along with our tutorial)
• “package main” is the starting package and “func main()” is the place where golang program starts the execution
• To build (compile) the golang program, first configure the environment variables
• Then open command prompt, go to working directory, and then use
• “go install”
• It’ll pull all the required packages to pkg folder and create an executable in bin folder

Go-Variables

• In golang, variables can be declared in 2 ways.
• Simple reference
• var intval int
• This variable will not have any memory. They are just references
• Direct assignment with allocation
• intval := 2
• This statement will declare an int type variable (type will be derived from right side of the operator), it will be allocated a memory and value 2 will be stored there
• Personally, I call it 3-in-1 functionality…

Structures

• For complex type of objects, golang provides the structures.
• If we want to represent any real world entity, then we need to describe the properties. Like,
• That car is red color
• It is produced by Hundai
• It is EON model
• ETC...
• In such cases, we need different properties like 
• Color
• Company
• Model
• Etc...
• golang provides the facility to represent such objects by structure. We can create basic template as given in example.

• In our case, structure will have 4 properties (you can add more as per your requirements).

• Now, creating an object is similar to create a variable
• You can create a reference or you can directly assign a new memory space along with reference creation.

Hence, Simple and Complex Variables

• According to golang syntax and standards,
• Local variables and structures should start with lowercase letter
• The names should be short, meaning full and self-explanatory
• For example,
• var i int (i = index)
• var ds departmentalstore (ds = departmental store)
• var fc foreigncurrency (fc = foreign currency)
• Go-compiler doesn’t allow you to create unused variables, that way, it tries to avoid un-necessary memory leaks
• Err variables should not be re-created at each iteration. Try to reuse it.