Questions regarding object instantiation/injection with multiple constructors
Questions tagged [multiple-constructors]
57 questions
400
votes
25 answers
Best way to do multiple constructors in PHP
You can't put two __construct functions with unique argument signatures in a PHP class. I'd like to do this:
class Student
{
protected $id;
protected $name;
// etc.
public function __construct($id){
$this->id = $id;
//…
Jannie Theunissen
- 28,256
- 21
- 100
- 127
60
votes
4 answers
In Scala, how can I subclass a Java class with multiple constructors?
Suppose I have a Java class with multiple constructors:
class Base {
Base(int arg1) {...};
Base(String arg2) {...};
Base(double arg3) {...};
}
How can I extend it in Scala and still provide access to all three of Base's constructors? In…
Seth Tisue
- 29,985
- 11
- 82
- 149
12
votes
6 answers
Choosing constructor for a noncopyable object
Assume I have a non-copyable class with multiple constructors with like this
class Foo: boost::noncopyable
{
public:
Foo(std::string s) {...}; // construct one way
Foo(int i) {...}; // construct another way
}
Now, I want to…
Roddy
- 66,617
- 42
- 165
- 277
11
votes
4 answers
How to extend ImageView in an Android-Scala app?
I have tried many solutions found in google by the keywords: multiple constructors, scala, inheritance, subclasses.
None seems to work for this occasion. ImageView has three constructors:
ImageView(context)
ImageView(context,attribute…
George Pligoropoulos
- 2,919
- 3
- 33
- 65
11
votes
5 answers
How to simplify multiple constructors?
I would like to have two constructors for a class, as follows:
public MyClass()
{
// do stuff here
}
public MyClass(int num)
{
MyClass();
// do other stuff here
}
Is the above the correct way to achieve my purpose? Is there some kind…
CJ7
- 22,579
- 65
- 193
- 321
10
votes
2 answers
Default value for boost::shared_ptr on class constructor
Suppose I have class like
class A{
public:
A(int a, boost::shared_ptr ptr){
// whatever!
}
};
My question is, what's the default value for that ptr? I'd like to be able to create an instance of that class using
A…
José Tomás Tocino
- 9,873
- 5
- 44
- 78
8
votes
2 answers
How to implement php constructor that can accept different number of parameters?
How to implement php constructor that can accept different number of parameters?
Like
class Person {
function __construct() {
// some fancy implementation
}
}
$a = new Person('John');
$b = new Person('Jane', 'Doe');
$c = new…
hoyomi
- 277
- 1
- 6
- 19
8
votes
3 answers
Few questions about constructors in C#
In C# regarding the inheritance of constructors:
I have read that constructors cannot be inherited.
If the base class contains a constructor, one or more, the derived class have to always call one of them? It is not possible that the derived class…
JeffreyZ.
- 387
- 1
- 3
- 7
8
votes
2 answers
javascript: different constructors for same type of object
is it possible to have more than one constructors for a class in javascript?
i.e. one with zero parameters, one with one, one with two, etc...
if so, how?
thanks!
clamp
- 33,000
- 75
- 203
- 299
8
votes
2 answers
MEF Constructor Parameters with Multiple Constructors
I'm starting to use MEF, and I have a class with multiple constructors, like this:
[Export(typeof(ifoo))]
class foo : ifoo {
void foo() { ... }
[ImportingConstructor]
void foo(object par1) { ... }
}
I am using…
InterWAS
- 183
- 1
- 2
- 7
7
votes
5 answers
this() and base() constructors in C#
There seems to be no language syntax for specifying both a this() and a base() constructor. Given the following code:
public class Bar : Foo
{
public Bar()
:base(1)
//:this(0)
{ }
public Bar(int schmalue)
:Foo(1)
{
…
Sprague
- 1,610
- 10
- 22
7
votes
3 answers
Which is better Java programming practice: stacking enums and enum constructors, or subclassing?
Given a finite number of items which differ in kind, is it better to represent them with stacked enums and enum constructors, or to subclass them? Or is there a better approach altogether?
To give you some context, in my small RPG program (which…
Arvanem
- 1,043
- 12
- 22
5
votes
6 answers
C++ constructor question
In the C++ programming for the absolute Beginner, 2nd edition book, there was the following statement:
HeapPoint::HeapPoint(int x, int y): thePoint(new Point(x,y)) { }
Is this equal to:
HeapPoint::HeapPoint(int x, int y) { thePoint = new…
Simplicity
- 47,404
- 98
- 256
- 385
4
votes
3 answers
Scala: Generic class with multiple constructors
I'm trying to create a generic class like this:
class A[T](v: Option[T]) {
def this(v: T) = this(Some(v))
def this() = this(None)
def getV = v
}
Then I do some testing:
scala> new A getV
res21: Option[Nothing] = None
scala> new A(8)…
Vilius Normantas
- 3,708
- 6
- 25
- 38
4
votes
2 answers
Inheriting constructors work only partially
I have following class, written so, as to work completely, whatever the typedef is:
class A
{
protected:
typedef uchar mDataType;
std::vector mData;
uint32 mWidth;
uint32 mHeight;
friend class C;
public:
A();
…
MKK
- 130
- 10