Hi, I was wondering what methods ending in an equal sign meant, but am not sure what to search for? Could anyone point me to any resources or tell me some terms to search for. Thanks! -Greg -- Posted via http://www.ruby-forum.com/.
Greg Christopher wrote:> Hi, > > I was wondering what methods ending in an equal sign meant, but am not > sure what to search for? Could anyone point me to any resources or tell > me some terms to search for. > > Thanks! > > -GregIt''s sugar syntax! So the method assign=(user_id), can be written in ruby: @object.assign = user_id Note the spaces around the equal sign :-) -- Posted via http://www.ruby-forum.com/.
Got it - maybe. I found a good resource[1], but I am not sure I
understand the value of the setter method in the first place. It would
seem that benefit is being able to skip explicitly calling save on an
object. Is that right?
If I had this method defined on my class:
def my_attribute=(some_value)
@some_value = some_value
end
I could call:
@object.my_attribute = new_value
instead of:
@object.my_attribute = new_value
@object.save
Is that the reason to define a setter method?
[1] http://rubylearning.com/satishtalim/ruby_syntactic_sugar.html
--
Posted via http://www.ruby-forum.com/.
On Sat, Sep 26, 2009 at 8:38 PM, Mario Gr <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> Got it - maybe. I found a good resource[1], but I am not sure I > understand the value of the setter method in the first place. It would > seem that benefit is being able to skip explicitly calling save on an > object. Is that right?The benefit of getter and setter methods are many - essentially they allow you to perform operations on the variable before and after they are retrieved or set. This is part of object-oriented methodology. But in reference to your first question - "I was wondering what methods ending in an equal sign meant", it is a feature of Ruby itself that methods can end in "!", "?" and "=", and the community has taken these to mean "potentially dangerous/exception creating", "interrogative (should return a boolean)" and "sets a variable", respectively.> If I had this method defined on my class: > > def my_attribute=(some_value) > @some_value = some_value > end > > I could call: > > -NHgb9tyinpnHCqZ3qdFy9g@public.gmane.org_attribute = new_value > > instead of: > > -NHgb9tyinpnHCqZ3qdFy9g@public.gmane.org_attribute = new_value > -jcFOJSd52/jfhZSSa7DgLw@public.gmane.org > > Is that the reason to define a setter method?No, because in #my_attribute=, you did not call save. Here is a reason to define a setter method: class Shape def save_intersection=(shape) @intersection = self.calculate_intersection(shape) end end That is, we need to calculate the intersection of these two shapes and then we can store the result in an instance variable. This is a good use of the setter syntax, because it sets a variable, and we need to do something "special". However, if we''re not doing anything special with the variable being set, it is preferable to write: class Shape attr_accessor :points end Which automatically defines the methods #points, which gets the instance variable @points, and #points=, which will set the instance variable if you used it like: shape = Shape.new shape.points = [1.2, 3,3] Colin
On Sat, Sep 26, 2009 at 9:31 PM, Colin Curtin <colin.t.curtin-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> in reference to your first question - "I was wondering what methodsEr, I mean, if that was you also. I forgot to check the original poster''s name. :D Colin
Yeah, i was using my buddy''s computer. So, I think I understand, but want to make sure I understand how I would use these practically. Basically, using these ruby shortcuts allows me to better work with and manage variables that I won''t immediately be saving with my object. For instance, in your special case, if I need to calculate the intersection of two shapes for the view, but didn''t need to save that value in my DB, then I would use the setter method? Maybe in your second example, where I''m doing nothing special, but had these points, I''d be using those points in a view or some other output, but wouldn''t be returning them to be stored on a record, at least not immediately. Yes? Thanks! -Greg -- Posted via http://www.ruby-forum.com/.
Greg Christopher wrote:> Yeah, i was using my buddy''s computer. > > So, I think I understand, but want to make sure I understand how I would > use these practically. Basically, using these ruby shortcuts allows me > to better work with and manage variables that I won''t immediately be > saving with my object.At this point, you should probably read Programming Ruby (or a similar book) and get a good understanding of accessor methods. There''s little or nothing Rails-specific in this discussion, and we are far enough toward the "Ruby basics" end of the spectrum that it will be a better use of everyone''s time and brain power if you come back after you do a bit of reading. Best, -- Marnen Laibow-Koser http://www.marnen.org marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org -- Posted via http://www.ruby-forum.com/.