Open struct for dynamic objects in Ruby - Step-by-Step Execution

Concept Flow - Open struct for dynamic objects

Create OpenStruct object

↓

Assign dynamic attributes

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Access or modify attributes

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Use object with flexible properties

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End

Create an OpenStruct object, add or change attributes anytime, then use it like a flexible object.

Execution Sample

Ruby

require 'ostruct'
person = OpenStruct.new
person.name = 'Alice'
person.age = 30
puts person.name
puts person.age

Creates a dynamic object 'person', adds name and age, then prints them.

Execution Table

Step	Action	Object State	Output
1	Create OpenStruct object	person = #<OpenStruct>
2	Assign person.name = 'Alice'	person = #<OpenStruct name="Alice">
3	Assign person.age = 30	person = #<OpenStruct name="Alice", age=30>
4	puts person.name	person = #<OpenStruct name="Alice", age=30>	Alice
5	puts person.age	person = #<OpenStruct name="Alice", age=30>	30

💡 All attributes assigned and printed; program ends.

Variable Tracker

Variable	Start	After 1	After 2	Final
person	#<OpenStruct>	#<OpenStruct name="Alice">	#<OpenStruct name="Alice", age=30>	#<OpenStruct name="Alice", age=30>

Key Moments - 2 Insights

How can we add new attributes to the OpenStruct object after creation?

You can assign new attributes anytime using dot notation like person.new_attr = value, as shown in steps 2 and 3.

What happens if we try to access an attribute that was never set?

Accessing an unset attribute returns nil without error, because OpenStruct allows dynamic properties.

Visual Quiz - 3 Questions

Look at the execution table, what is the state of 'person' after step 2?

A #<OpenStruct name="Alice">

B #<OpenStruct>

C #<OpenStruct age=30>

D #<OpenStruct name="Alice", age=30>

💡 Hint

Check the 'Object State' column in row 2 of the execution_table.

At which step is the 'age' attribute added to 'person'?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look for the assignment of person.age in the 'Action' column.

If we try to access person.height without setting it, what will happen?

A Raises an error

B Returns 0

C Returns nil

D Returns an empty string

💡 Hint

Refer to key_moments about accessing unset attributes.

Concept Snapshot

OpenStruct creates flexible objects.
Assign attributes anytime with dot notation.
Access unset attributes returns nil.
Good for dynamic, simple data containers.

Full Transcript

This example shows how to use Ruby's OpenStruct to create an object that can have attributes added or changed anytime. We start by creating an empty OpenStruct object called person. Then we add a name attribute with 'Alice' and an age attribute with 30. When we print these attributes, we get 'Alice' and '30' as output. OpenStruct lets you add new properties on the fly and access them easily. If you try to read an attribute that was never set, it returns nil instead of causing an error. This makes OpenStruct useful for flexible data objects.