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How can I add an instance variable to a defined class at runtime, and later get and set its value from outside of the class?
I'm looking for a metaprogramming solution that allows me to modify the class instance at runtime instead of modifying the source code that originally defined the class. A few of the solutions explain how to declare instance variables in the class definitions, but that is not what I am asking about.
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An instance variable in ruby has a name starting with @ symbol, and its content is restricted to whatever the object itself refers to. Two separate objects, even though they belong to the same class, are allowed to have different values for their instance variables.
Explanation: Yes, Module instance variables are present in the class when you would include them inside the class.
class . There are no "static methods" in the C# sense in Ruby because every method is defined on (or inherited into) some instance and invoked on some instance. Accordingly, they can access whatever instance variables happen to be available on the callee.
Instance variables are created when an object is created with the use of the keyword 'new' and destroyed when the object is destroyed. Instance variables hold values that must be referenced by more than one method, constructor or block, or essential parts of an object's state that must be present throughout the class.
Ruby provides methods for this, instance_variable_get and instance_variable_set. (docs)
You can create and assign a new instance variables like this:
>> foo = Object.new => #<Object:0x2aaaaaacc400> >> foo.instance_variable_set(:@bar, "baz") => "baz" >> foo.inspect => #<Object:0x2aaaaaacc400 @bar=\"baz\"> If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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