Fixed documentation that implies the introduction of a mutability bug #394
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Setting the default value to a hash (or empty array, or any other mutable object) can cause mutability/side-effect problems to be introduced. These are very hard and time-consuming to track down.
For example:
u1 = User.new
u1.info[:something] = 1
u2 = User.new
u2.info[:something] # => 1
In the above example, one would expect `u2.info[:something]` to return `nil`, however because the default value Hash is shared between all users, `u2.info[:something]` returns `1`.
Using the lambda means that a new Hash will be created each time a new user is created, avoiding the above side-effect issue:
u1 = User.new
u1.info[:something] = 1
u2 = User.new
u2.info[:something] # => nil
with the rest of the readme
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Setting the default value to a hash (or empty array, or any other mutable object) can cause mutability/side-effect problems to be introduced. These are very hard and time-consuming to track down.
For example:
In the above example, one would expect
u2.info[:something]to returnnil, however because the default value Hash is shared between all users,u2.info[:something]returns1.Using the lambda means that a new Hash will be created each time a new user is created, avoiding the above side-effect issue: