accessor

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Difference between class property mVar and instance variable self.mVar I am new to developing in Objective-C and I couldn't quite figure out what the difference is between the following: First let me explain my situation. I've got an NSMutableArray , and I created and outlet for it in my .h file. Now when I assign an array to it as self.myMutableArray=myArray I get an error; However just myMutableArray=myArray

问题 I have 3 fields in my form witch are not in my database: opening_type, opening_hours, opening_minutes. I want to update the main attribute "opening" (in database) with these 3 fields. I tried lot of things that doesn't work. Actually I have: attr_accessor :opening_type, :opening_hours, :opening_minutes def opening_type=(opening_type) end def opening_type opening_type = opening.split("-")[0] if !opening.blank? end def opening_hours=(opening_hours) end def opening_hours opening_hours = opening

问题 I'm a little confused by whether Core Data generates primitive accessors for NSManagedObject subclasses in the form setPrimitiveAttributeName:, as compared to the form setPrimitiveValue: forKey:, which it seems to do consistently. The source of my confusion is that I have used the modeling tool (XCode 4) to generate NSManagedSubclasses for two of my entities, which, as far as I can tell, share the same metadata settings, yet one subclass recognizes the setPrimitiveAttributeName form, whereas

问题 I dont understand why some fields of my models clash. I dont have any foreign key so why would they clash ?! Here is my code: from __future__ import unicode_literals from django.db import models from django.contrib.auth.models import AbstractUser import datetime import uuid # Create your models here class Patients(AbstractUser): id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False) first_name = models.CharField(max_length = 255) last_name = models.CharField(max_length =

问题 A class contains a std::vector<int*> . External code needs read-only access to this vector, should not be able to modify the contents (neither the pointers or their contents). Inside the class, the values may change (e.g. double_values() , and so storing them as a std::vector<const int*> is not possible. Is there a way to return the std::vector<int*> as a std::vector<const int*> without making a copy? It feels like there should be, because const is simply operating at compile time to say what

问题 I have MyObject and MyTrait: class MyObject(private val myname: String = "") extends MyTrait { _name = myname def foo(myname : String) { _name = myname } } trait MyTrait { protected var _name: String = _ def name = _name } This works fine as this val myObject = new MyObject("abc") println(myObject.name) myObject.foo("def") println(myObject.name) prints abc def as expected. Problem now is that I want MyTrait._name to be a val instead of a var. But there is no way I can manage to get this to

问题 I've been learning Java these days and what I've read just is "Be careful not to write accessor methods that return references to mutable objects" which is really interesting. And now I am wondering whether it is same for Properties and Accessor methods in C#? Or C# already returns cloned copies automatically? Thanks. 回答1: A reference is just that... a reference to some object that is stored in memory. Unless you explictly write code to create a clone and return a reference to that object,

问题 I'm new to Java, but have some OOP experience with ActionScript 3, so I'm trying to migrate relying on stuff I know. In ActionScript 3 you can create getters and setters using the get and set keywords, meaning you create a method in the class and access data through a property of an instance of that class. I might sound complicated, but it's not. Here's an example: class Dummy{ private var _name:String; public function Dummy(name:String=null){ this._name = name; } //getter public function get

问题 What is the nce between accessing a property via "propertyname" versus "self.propertyname" in objective-c? Can you cover in the answer: What is best practice? How do the two approaches affect memory management (retain counts / one's responsibilities for memory management) Any other advantages/disadvantages The assumption for the scenario could be based on the following: Header file @interface AppointmentListController : UITableViewController { UIFont *uiFont; } @property (nonatomic, retain)

问题 I need something similar to ReadToEnd or ReadAllBytes to read all of the contents of the MemoryMappedFile using the MappedViewAccessor if I don't know the size of it, how can I do it? I have searched for it, I have seen this question, but it is not the thing I am looking for: How can I quickly read bytes from a memory mapped file in .NET? Edit: There is a problem, the (int)stream.Length is not giving me the correct length, it rather gives the size of the internal buffer used! I need to