CODEWITHSUNDEEP
rubysinatra
Martin Konecny
Martin Konecny

Reputation: 59571

Modifying predefined 'params' var in Sinatra renders it nil

Consider the simple following code:

post '/xxx' do
    puts params
end

this works fine. Now consider the following modification

post '/xxx' do
    params = params
    puts params
end

Now params is nil!! I am new to Ruby, and have no idea why this behaviour is happening. Obviously I do not want to execute the useless params = params expression, but I was trying to to something a little more complicated involving modifying params and found that it always becomes nil.

Upvotes: 0

Views: 397

Answers (1)

georgebrock
georgebrock

Reputation: 30023

In the first version, you're calling a method called params and passing its return value to puts.

In the second version, you're creating a local variable called params (which hides the method with the same name) and assigning it to itself.

Consider the following example:

def foo
  1
end

p foo # outputs `1`

foo = foo

p foo # outputs `nil`

It might not be obvious that this is happening, because in Ruby accessing a local variable and calling a method on self look exactly the same.

Upvotes: 5

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