Go Type System: Assertions vs Conversions

Unleash the Power of Type Assertions and Conversions in Go

Getting Started

Before we dive into the world of type assertions and conversions in Go, make sure you have Go installed and a code editor ready. You can find a simple walkthrough to install Go here. For a code editor, you can choose from popular options like Sublime Text, Visual Studio Code, or similar.

Type Assertions and Conversions: What You Need to Know

In Go, type assertions and conversions are essential concepts that help you work with variables efficiently. Here’s a sneak peek at what you’ll learn:

• What is type assertion?
• What is type conversion?
• How to perform type assertions in Go
• The art of type conversion

Type Assertion: Uncovering the Underlying Type

Type assertion is a process that checks the underlying type of an empty interface variable. In Go, this is done using the syntax t := i.(type). But what does this syntax entail?

• i is the variable whose type we’re asserting, which must be defined as an interface
• type is the type we’re asserting our variable is (such as string, int, float64, etc.)
• t is a variable that stores the value of our variable i, if our type assertion is correct

Handling Uncertainty in Type Assertions

When type assertions are unsuccessful, they throw an error referred to as a “panic” in Go. To avoid this, you can use a second variable on the left side of your type assertions or employ type switching.

Type Switching: A Powerful Alternative

Type switching is similar to a normal switch statement, but it switches through possible types of a variable rather than values. This allows you to extract the type from your interface variable and switch through several type options.

The Role of Empty Interfaces

An empty interface is a definition of the methods and attributes of a variable type without specifying them until initialization. Type assertions are performed on interface variables to assert their underlying type.

Type Conversion: Changing the Game

Type conversion is the process of changing a value from one type to another. In Go, types can only be converted between related or similar types. Let’s explore an example:

• We can convert an int value to a float64 because they share similar data structures
• We can also convert a custom type myString to string and vice versa because they inherit the same data structure

Key Takeaways

The main difference between type assertion and type conversion lies in their syntax and approach. Type assertion relies on an interface variable to extract the underlying type, while type conversion relies on the similarity of data structures for convertibility.

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