Hi all
irb(main):001:0> “” || “asdf”
=> “”
irb(main):002:0> nil || “asdf”
=> “asdf”
irb(main):003:0>
I’d like the first one to also return “asdf”. So is there an operator
that fits my needs? 
Thanks
Josh
“” or “asdf”
nil or “asdf”
Quoth Joshua M.:
Thanks
Josh
irb(main):001:0> str = “”
=> “”
irb(main):002:0> str != “” || “asdf”
=> “asdf”
irb(main):003:0> nil || “asdf”
=> “asdf”
HTH,
Joshua M. wrote:
Hi all
irb(main):001:0> “” || “asdf”
=> “”
irb(main):002:0> nil || “asdf”
=> “asdf”
irb(main):003:0>I’d like the first one to also return “asdf”. So is there an operator
that fits my needs?Thanks
Josh
I guess you could do something cool like
class String
def |(str)
return str if self.eql?("")
end
end
~Jeremy
Konrad M. wrote:
Quoth Joshua M.:
Thanks
Joshirb(main):001:0> str = “”
=> “”
irb(main):002:0> str != “” || “asdf”
=> “asdf”
irb(main):003:0> nil || “asdf”
=> “asdf”HTH,
The problem is, in my Rails app I sometimes have a variable set to “”
(empty user input) or nil.
<%= “The variable is #{(var || “empty”)}” %>
With your version I won’t get “empty” when the var is nil:
<%= “The variable is #{(var != “” || “empty”)}” %>
var = nil
=> The variable is # nothing here…
var = “asdf”
=> The variable is asdf
actually, that doesn’t work. sorry.
On Nov 6, 6:41 pm, Joshua M. [email protected] wrote:
Hi all
irb(main):001:0> “” || “asdf”
=> “”
irb(main):002:0> nil || “asdf”
=> “asdf”
irb(main):003:0>I’d like the first one to also return “asdf”. So is there an operator
that fits my needs?
“” isn’t false so || and or won’t work. You’ll have to code it
differently. E.g.:
a = “a string”
a || (a.empty? ? “asdf” : a)
On 11/6/07, yermej [email protected] wrote:
that fits my needs?
“” isn’t false so || and or won’t work. You’ll have to code it
differently. E.g.:a = “a string”
a || (a.empty? ? “asdf” : a)
This doesn’t work for me. The previous one doesn’t either. This one
does (I’m sure someone could easily clean this up, I feel lazy
though)…
[nil, “”, “something”].each do |i|
puts( (item ||= “”).empty? ? “asdf” : item )
end
That results in…
asdf
asdf
something
Todd
On 11/6/07, Todd B. [email protected] wrote:
I’d like the first one to also return “asdf”. So is there an operator
though)…[nil, “”, “something”].each do |i|
puts( (item ||= “”).empty? ? “asdf” : item )
There should be an additional closing ) on the previous line of code
end
Todd
On Nov 6, 6:31 pm, Joshua M. [email protected] wrote:
The problem is, in my Rails app I sometimes have a variable set to “”
(empty user input) or nil.
This is why ActiveSupport has the #blank? method:
irb(main):001:0> require ‘rubygems’
=> true
irb(main):002:0> require ‘active_support’
=> true
irb(main):003:0> nil.blank?
=> true
irb(main):004:0> “”.blank?
=> true
irb(main):005:0> “foo”.blank?
=> false
irb(main):006:0> false.blank?
=> true
irb(main):007:0> 0.blank?
=> false
On Nov 6, 2007, at 9:25 PM, Todd B. wrote:
This doesn’t work for me. The previous one doesn’t either. This one
Todd
I use these extensions in several projects for exactly the same reason
as the OP
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
irb(main):018:0> “”.nonblank? || “asdf”
NoMethodError: undefined method blank?' for "":String from (irb):4:in nonblank?’
from (irb):18
Ok, so these are typically Rails projects, but you can take the
String#blank? extension from ActiveSupport
irb(main):019:0> class String #:nodoc:
irb(main):020:1> def blank?
irb(main):021:2> empty? || strip.empty?
irb(main):022:2> end
irb(main):023:1> end
=> nil
irb(main):024:0>
And then Joshua’s orignal examples become:
irb(main):025:0* “”.nonblank? || “asdf”
=> “asdf”
irb(main):026:0> nil.nonblank? || “asdf”
=> “asdf”
And for completeness:
irb(main):027:0> “jkl;”.nonblank? || “asdf”
=> “jkl;”
-Rob
2007/11/7, Rob B. [email protected]:
irb(main):003:0>
end
end
irb(main):019:0> class String #:nodoc:
=> “asdf”
irb(main):026:0> nil.nonblank? || “asdf”
=> “asdf”And for completeness:
irb(main):027:0> “jkl;”.nonblank? || “asdf”
=> “jkl;”
Why not simply define a global method?
def substitute_default(s, fallback)
s.nil? || s == “” ? fallback : s
end
The name of course is just a suggestion.
Kind regards
robert
On Nov 7, 10:36 am, Joshua M. [email protected] wrote:
class String
def |(alternative)
(self.nil? or self == “”) ? alternative : self
end
end
An instance of a String class will never be an instance of NilClass
instead. You can remove “self.nil? or” from the above.
I finally came up with this:
class String
def |(alternative)
(self.nil? or self == “”) ? alternative : self
end
end
class NilClass
def |(alternative)
alternative
end
end
Is this OK? Or do I accidently override some existing method? Because
without the definition above
nil | “asdf”
returns
true!
On Nov 7, 2007 6:52 PM, Rob B. [email protected]
wrote:
That’s because NilClass#| is already defined so you probably should
leave it alone.
Hey this is cool, it seems that
!!x == nil | x
R.
On Nov 7, 2007, at 12:36 PM, Joshua M. wrote:
alternative
true!
That’s because NilClass#| is already defined so you probably should
leave it alone.
For the String part, you’ll only ever get truth from self.nil? if self
really is nil so that method would be better refactored as:
class String
def |(alternative)
empty? ? alternative : self
end
end
-Rob