Hi there
im writing a class which produces refrences in a hash
however im trying to deal with multiple authors
so i want to write an if statement where
if the key already exists
push value onto it
im unsure of how to do this so any help would be much appreciated
many thanks
code:
class Reference
@data
add_field(field, value)
if key already exits
push value onto it
else
@data[field]=value
end
get(field)
@data[field]
end
end
2007/12/10, Johnathan S. [email protected]:
im writing a class which produces refrences in a hash
however im trying to deal with multiple authors
so i want to write an if statement where
if the key already exists
push value onto it
im unsure of how to do this so any help would be much appreciated
The easiest and probably most appropriate idiom is to use the block
form of Hash.new:
irb(main):001:0> authors = Hash.new {|h,k| h[k] = []}
=> {}
irb(main):002:0> authors[:foo] << “bar”
=> [“bar”]
irb(main):003:0> authors[:foo] << “baz”
=> [“bar”, “baz”]
irb(main):004:0> authors[:bar] << “foo”
=> [“foo”]
irb(main):005:0> authors
=> {:foo=>[“bar”, “baz”], :bar=>[“foo”]}
Note, this will make all Hash values Arrays but this is easier to
deal with anyway. Otherwise you would have to write code that deals
with single and multiple values in every bit of code that uses this.
Kind regards
robert
hi and thanks for your help its much appreciated
i would really prefer if i got this working inside the class however.
are you able to assist?
thanks
On 10.12.2007 17:01, Johnathan S. wrote:
hi and thanks for your help its much appreciated
i would really prefer if i got this working inside the class however.
are you able to assist?
What do you mean? The solution works inside and outside of classes.
robert
Johnathan S. wrote:
hi and thanks for your help its much appreciated
i would really prefer if i got this working inside the class however.
are you able to assist?
thanks
class Foo
def initialize
@authors = Hash.new {|h,k| h[k] = []}
end
def add(field, value)
if @authors.has_key?(field)
@authors[field] << value
else
@authors[field] = value
end
end
def
@authors[field]
end
end
Perhaps something like that?
I just quickly typed that up whilst trying to work and talk to my boss,
so my apologies if it doesn’t work or there are spelling mistakes
Regards,
Lee