accessor

I'm learning Swift and I'm reading The Swift Programming Language from Apple, I have no Objective C background (only PHP, JS, and other but no Obj C) On page 24-25 I see this code: //...Class definition stuff... var perimeter: Double { get { return 3.0 * sideLength } set { sideLength = newValue / 3.0 } } //...Class continues... This part is NOT specified in the book and I can't get what those are for. Can anyone explain me what get and set are? That's actually explained right before the code: In addition to simple properties that are stored, properties can have a getter and a setter. class

Consider this simple example import pandas as pd df = pd.DataFrame({'one' : [1,2,3], 'two' : [1,0,0]}) df Out[9]: one two 0 1 1 1 2 0 2 3 0 I want to write a function that takes as inputs a dataframe df and a column mycol . Now this works: df.groupby('one').two.sum() Out[10]: one 1 1 2 0 3 0 Name: two, dtype: int64 this works too: def okidoki(df,mycol): return df.groupby('one')[mycol].sum() okidoki(df, 'two') Out[11]: one 1 1 2 0 3 0 Name: two, dtype: int64 but this FAILS def megabug(df,mycol): return df.groupby('one').mycol.sum() megabug(df, 'two') AttributeError: 'DataFrameGroupBy' object

I just upgraded my prototyping tuple to a record. Someday it may become a real class. In the meantime, I want to translate code like this: type Example = int * int let examples = [(1,2); (3,4); (5,6)] let descs = Seq.map (fst >> sprintf "%d") examples to this: type Example = { Field1 : int Field2 : int Description : string } let examples = [{Field1 = 1; Field2 = 2; Description = "foo"} {Field1 = 3; Field2 = 4; Description = "bar"} {Field1 = 5; Field2 = 6; Description = "baz"}] let descs = Seq.map Description examples The problem is that I expected to get a function Description : Example ->

When we define a property like public string Name {get; set;} dot net can make our properties code. but when we use public string Name {get;} public string Name {set;} we face with 'Hajloo.SomeThing.PropertyName.set' must declare a body because it is not marked abstract or extern. Automatically implemented properties must define both get and set accessors. Actually why the compiler can't determine the property and make code automatically? What's the problem? Because the auto-implemented properties generate their own backing store for the property values. You have no access to the internal

Just wondering if anyone can shed some light on the basics of getter setters in Ruby on Rails with a view on strongly typed. I am very new to ruby on rails and predominately have a good understanding of .NET. For example, let's consider we have a .net class called Person class Person { public string Firstname{get;set;} public string Lastname{get;set;} public Address HomeAddress{get;set;} } class Address { public string AddressLine1{get;set;} public string City{get;set;} public string Country{get;set;} } In Ruby, I would write this as class Person attr_accessor :FirstName attr_accessor