The following is a guest post by Trevor McKendrick and originally appeared on his blog. Trevor is currently in the Ruby-003 class at The Flatiron School. You can follow him on Twitter here.
1. Set a default value for an attribute accessor:
class Person
attr_accessor_with_default :age, 25
end
2. Try: invokes the public method passed as a parameter, but returns nil if it doesn’t exist
@person.try(:name)
3. Use grep to search the methods of an object:
>> Object.methods.grep /inspect/
=> [“inspect”, “pretty_inspect”, “pretty_print_inspect”]
4. Mark deprecated code with Kernel#warn
class Foo
# DEPRECATED: Please use useful instead.
def useless
warn “[DEPRECATION] `useless` is deprecated. Please use `useful` instead.”
useful
end
def useful
# ...
end
end
5. “Pretend” flag gives a dry run if you’re not sure what the Rails Generate command is going to create
>> rails generate model Blog -p
6. The operator =~ matches a String against a regular expression. It returns the position/index where the String was matched – or nil if no match was found:
/Quick/ =~ “Ruby Quicktips”
=> 5
# Order does not matter
“Ruby Quicktips” =~ /Quick/
=> 5
“Ruby Quicktips” =~ /foo/
=> nil
7. Check syntax without executing the program:
>> ruby -c filename.rb
8. In IRB, assign last evaluated expression after it runs
>> 2 + 5
=> 7
>> x = _
=> 7
>> x
=> 7
9. Create hash from array
>> arr = [:a, 1, :b, 2]
>> Hash[*arr]
=> {:a => 1, :b => 2}
10. Join elements in an array
>>[1,2,3,4] * “,”
=> 1,2,3,4
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