Hey guys,
I find myself doing stuff like this a lot:
self.email.blank? ? self.name : self.email
Anyone feel like adding an ‘or’ method to nil and String (a la blank?) so that this will work:
self.email.or(self.name)
It would be as simple as adding this file to ActiveSupport
activesupport/lib/core_ext/or.rb
class String def or(val) self == “” ? val : self end end
class NilClass def or(val) val end end
I’ll submit a patch of this + tests to LH if people are interested.
Re: [Rails-core] Addition of ‘or’ method to String and NilClass in core_ext Hi,
How about adding some method #foo instead that returns nil if the string is blank and self otherwise, so that you can do:
self.email.foo || self.name
This looks slightly better and more intuitive to me, if we can figure out a descriptive name for the #foo method (I can’t think of any atm, admittedly).
Cheers
Pascal
ifempty?
Pascal Ehlert wrote:
I do it like this:
Long story short:
class Foo attr_accessor :bar nillify_blank :bar end f = Foo.new
=> #<Foo:0x4fe8a68>
f.bar = ""
=> ""
f.bar
=> nil
Then you can use the || operator naturally.
Chris
Since ActiveSupport already has #blank?, you can easily give yourself a #nonblank? The symmetry with the Numeric#nonzero? is nice.
-Rob
class String # Allowing a chain like: string_value.nonblank? || 'default value' def nonblank? self unless blank? end end
class NilClass # Allowing a chain like: value.nonblank? || 'default value' def nonblank? self end # so it plays nicely with Numeric#nonzero? def nonzero? self end end
I just found out google groups was bouncing my emails because they were coming from a different address, so to sum them all up in one:
I also realized that I do crap like this a lot too:
self.owner_object_association ? self.owner_object_association : default_thing
Where this would give me:
self.owner_object_association.or_if_blank? default_thing
Maybe just add it to Object?
class Object def or_if_blank?(val) if respond_to? :blank? return self.blank? ? val : self
else
self
end
end
end
class NilClass def or_if_blank?(val) val end end
That way you get it everywhere blank? is defined (Hash, Array, String, Nil, Numeric)
And the problem with http://gist.github.com/53846 is that I don’t think you can do stuff on regular strings like this:
user_msg = params[:stuff].or_if_blank? ‘didnt type anything’
-Ryan
+1 for or_if_blank?. Some minor suggestions:
1. I think there does not need to be a special implementation for NilClass, since nil.blank? => true.
2. I would consider leaving out the "?" from the method name. ?- methods tend to evaluate to a boolean. This one doesn't.
3. The return can be omitted.
Tim
+1 for the suggestions. I’ll submit a patch to LH later today.
LH ticket created: http://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/1815-patch-add-or_if_blank-to-object
I also realized that I do crap like this a lot too:
self.owner_object_association ? self.owner_object_association : default_thing
Where this would give me:
self.owner_object_association.or_if_blank? default_thing
I really don't like "or_if_blank?" It feels like it should live in a gem,
partly because it doesn't seem necessary, and partly because there are too many variants I could see people needing.
or_if_nil or_if_blank or_if_present or_if_a_plate_of_chips
But saying that,
A clear distinctinction needs to be made between;
>> a.blank? ? b : a
and
>> a.or_if_blank?(b)
namely, in the first "b" only gets evaluated ONLY IF "a" is blank in the second, "b" ALWAYS get evaluated.
It's not necessarily a problem. But I worry that we'll see code like;
>> a.or_if_blank? (call_a_function_that_does_something_bad_but_also_returns_something)
Perhaps a different approach would be something like this
>> user.bumblebee (:full_name, :email, :something_else, :another_fallback)
which is equivalent to;
>> if user.full_name.present? >> return user.full_name >> elsif user.email.present? >> return user.email >> elsif user.something_else.present? >> return user.something_else >> elsif user.another_fallback.present? >> return user.another_fallback >> end
The bumblebee hovers around the user, looking for a flower with some pollen.
It goes from flower to flower, trying each method in order, and when it finds one that isn't empty, it returns it to the hive.
I cemented the BumbleBee in a gist.
how do you suggest to make it cater for fallbacks that doesn’t necessarily belong to a method in the object? e.g.:
user.name.blank? ? user.name : “An arbitrary value”
–stephen
how do you suggest to make it cater for fallbacks that doesn't necessarily belong to a method in the object? e.g.:
user.name.blank? ? user.name : "An arbitrary value"
--stephen
BumbleBees are very versatile creatures. And they return a nil if they can't find any flowers.
See the discussion on the ticket for a nice lazy evaluation feature using blocks.
-Tim