Symbols are great, we use them in hashes all the time…but did you know, symbols aren’t part of Rails’ garbage collection? When you create them, the memory the use has been allocated permanently! Why is this bad? So if we create a handful of symobls…no biggie, but what if we’re dynamically creating lots and lots of them? Major faux pas!
This was brought to my attention last night when I was trying to create a hash with some dynamic symbols. See below:
## here is some data
>> hardware = Hardware.find(:all, :limit => 2)
=> [#<Hardware id: 1, name: "Bolts", description: "Lorem ipsum dolor sit amet, consectetur adipisicing...", photo_front_file_name: "144_replica_wheels_Closeout_30_percent_off_prices_l...", photo_front_content_type: "image/jpeg", photo_front_file_size: 80842, photo_angle_file_name: nil, photo_angle_content_type: nil, photo_angle_file_size: nil, created_at: "2009-02-19 11:04:48", updated_at: "2009-02-20 20:29:46">, #<Hardware id: 2, name: "Nuts", description: "Lorem ipsum dolor sit amet, consectetur adipisicing...", photo_front_file_name: nil, photo_front_content_type: nil, photo_front_file_size: nil, photo_angle_file_name: nil, photo_angle_content_type: nil, photo_angle_file_size: nil, created_at: "2009-02-19 11:04:48", updated_at: "2009-02-20 07:18:32">]
>> y hardware.first
--- !ruby/object:Hardware
attributes:
name: Bolts
updated_at: 2009-02-20 20:29:46
photo_angle_file_size:
photo_front_file_name: 144_replica_wheels_Closeout_30_percent_off_prices_listed_.jpg
photo_front_file_size: "80842"
id: "1"
description: Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in recodehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
photo_angle_content_type:
photo_front_content_type: image/jpeg
created_at: 2009-02-19 11:04:48
photo_angle_file_name:
attributes_cache: {}
=> nil
## don't do this
for hardware_item in hardware
formatted[:#{hardware_item.name.downcase}] = hardware_item.description
end
>> formatted[:bolts]
=> "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in recodehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
## this is better
for hardware_item in hardware
formatted[hardware_item.name.downcase] = hardware_item.description
end
>> formatted['bolts']
=> "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in recodehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
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