scala - Override field with parameterless method -

-

I am currently learning Scala and I am reading Martin Ordesky's book (from the cover). In Chapter 10 I found this:

Enter image details here < P> Excellent I understand both and in this way. So I tried an example: 

  class father {def x = 1 // method} increases the child's dad in the class (overlays well x = 1; // field}   
 However, if you try to override an attribute with a method:  
  class father father {val x = 1; // field} class I get a compiler error:  
  The method x should be a static, irreversible value override (override def x = 1 // method)   
 Def X = 1   
 This does not work if  x  is in  dad   var :  
  Method x can not override a floating variable override def x = 1   
 so we have two cases (and I have two questions):  < Ul> 
  •   Trying to override an unqualified field:  In this order of guarantee,  x  will not be overridden by a method whose value varies more Until the time? Is there any other reason?  
  •   A The variable region is trying to override:  Why can not override an unqualified area? I initially thought that this is to avoid class users assigning values ​​to parameters without parameters, but then no parameter-based method should be allowed.    
     
     
     a  val  to  def  
     A  var  should be allowed to override at  def  what will it mean?

    • Comments

    Post a Comment

    Popular posts from this blog

    php - PDO bindParam() fatal error -

    -
    I am trying to learn PDO, now I have written this small code, but it gives me a serious error: Fatal error: Call a member function at a non-object dot () ... $ con = new mysqli ("127.0.0.1", "root", "", "csvdangercheck"); $ Query = $ con- & gt; ("Id,` var1`, `var2`) values ​​(" id,: var1,: var2) ";); $ query- & gt; bypass pattern (': id', $ id); $ query- & gt; BindParam (': var1', $ VAL1); $ Query- & gt; bindParam (': var2', $ val2); $ Query-> Executed (); I Trying to use print_r ($ con-> errorInfo ()) but Fatal error: Undefined method mysqli :: errorInfo ( ) ... can someone tell me what am I missing? Flaffeh said, you have PDO Missing Mysqy, try it: $ con = new PDO ('mysql: host = 127.0.0.1; dbname = csvdangercheck', 'root', '');
    Read more

    php - How can I cram 6+31 numeric characters into 22 alphanumeric characters? -

    -
    I have a 6 digit number and a 31-digit number (such as "234536" and "201103231043330478311223582826") that I The API needs to be crawled in the same 22-character alphanumeric field that uses PHP. I tried to convert each one to 32 (using custom code could not handle the base_convert () large number) and to connect with a single-character delimiter, but It only gives me 26 characters This is a restore API, so the letters should be URI-protected. I would like to do a database table cross with two references without reference to another reference value, if possible, any suggestions? Instead use a radix of 62. This will give you 22 characters for the top, 3.35 for the pre and 17.3 for the next. & gt; & Gt; & Gt; Math.log (10 ** 6) /math.log (62) 3.3474826039165504 & gt; & Gt; & Gt; Math.log (10 ** 31) /math.log (62) 17.295326786902177
    Read more

    logging - How can I log both the Request.InputStream and Response.OutputStream traffic in my ASP.NET MVC3 Application for specific Actions? -

    -
    For a specific set of tasks, I need to log in to the incoming request inputstream as well as outgoing response. is. I am using an ActionFilterAttribute for this and overriding the OnActionExecuted and OnResultExecuted methods. So I'm starting with this idea ... Public category ActionLoggerAttribute: ActionFilterArrbit {Public Override Zero On-Offed Execution (ActionActioned Contact Filter Filter) {base.OnActionAxecuted (FilterContext); HttpRequestBase request = filterContext.HttpContext.Request; // TODO: Log the request. InputStream} Public Override Zero OnResultExecuted (ResultExecutedContext FilterContext) {base.OnResultExecuted (filterContext); HTTPRPSPointBase Response = FilterContacts Hpptex response; // TODO: Log on Response.OutputStream}} Ideally I'll hook it up with enterprise library logging because I'm already using it for error logging. Am I reaching the input and output stream at the right time? Can I easily use the Enterprise Library to log i...
    Read more