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Ruby / Objects and Classes

Instance variables

Learn instance variables in Ruby through a focused explanation, a dedicated topic-specific example, an engineering boundary, and a mastery check.

12 min read • Intermediate

instance variables is an atomic Ruby topic inside Objects and Classes. The example uses the named construct directly so you can see its syntax, data flow, and observable behavior.

Read the code by locating the exact feature named instance variables, then trace the value before and after that feature runs. This lesson is intentionally isolated from neighboring topics: changing identifiers alone would not reproduce the same behavior because the construct itself is different.

Topic-specific example

ruby-0043-5fd9ad3caa.rb
ruby Try It Live 
class Counter;def initialize;@n=0;end;def inc;@n+=1;end;end;c=Counter.new;puts c.inc
Edge case / engineering note

For instance variables, test the boundary that makes the feature meaningful: invalid input, an empty value, a missing branch, lifecycle/cleanup, or a type/runtime constraint. Do not infer correctness only from the happy path.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

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