How do you create an array of classes?
I want to make an array of classes in TypeScript. This is possible in vanilla JavaScript:
class A {
constructor() {console.log('constructor');}
a() {}
}
const array = [A];
new (array[0])(); // Prints 'constructor'
I want to make the array type safe using an interface. This is my attempt to implement this in TypeScript:
interface I {
a();
}
class A implements I {
constructor() {console.log('constructor')}
a() {}
}
const array: I = [A];
new (array[0])();
When I compile this, I get this error:
Error:(16, 21) TS2322: Type 'typeof A' is not assignable to type 'I'.
Property 'a' is missing in type 'typeof A'.
Because this error message mentions that typeof A is not assignable to type 'I', it seems that arrays can not contain classes, as typeof is used for instantiated objects.
What I need is a way to group all my classes in a single variable without instantiating them, and be able to access the class by index. How can I achieve this in TypeScript?
typescript class
asked Nov 22 '18 at 20:09
Makoto EmuraMakoto Emura
116210
add a comment |
I want to make an array of classes in TypeScript. This is possible in vanilla JavaScript:
class A {
constructor() {console.log('constructor');}
a() {}
}
const array = [A];
new (array[0])(); // Prints 'constructor'
I want to make the array type safe using an interface. This is my attempt to implement this in TypeScript:
interface I {
a();
}
class A implements I {
constructor() {console.log('constructor')}
a() {}
}
const array: I = [A];
new (array[0])();
When I compile this, I get this error:
Error:(16, 21) TS2322: Type 'typeof A' is not assignable to type 'I'.
Property 'a' is missing in type 'typeof A'.
Because this error message mentions that typeof A is not assignable to type 'I', it seems that arrays can not contain classes, as typeof is used for instantiated objects.
What I need is a way to group all my classes in a single variable without instantiating them, and be able to access the class by index. How can I achieve this in TypeScript?
typescript class
asked Nov 22 '18 at 20:09
Makoto EmuraMakoto Emura
116210
add a comment |
I want to make an array of classes in TypeScript. This is possible in vanilla JavaScript:
class A {
constructor() {console.log('constructor');}
a() {}
}
const array = [A];
new (array[0])(); // Prints 'constructor'
I want to make the array type safe using an interface. This is my attempt to implement this in TypeScript:
interface I {
a();
}
class A implements I {
constructor() {console.log('constructor')}
a() {}
}
const array: I = [A];
new (array[0])();
When I compile this, I get this error:
Error:(16, 21) TS2322: Type 'typeof A' is not assignable to type 'I'.
Property 'a' is missing in type 'typeof A'.
Because this error message mentions that typeof A is not assignable to type 'I', it seems that arrays can not contain classes, as typeof is used for instantiated objects.
What I need is a way to group all my classes in a single variable without instantiating them, and be able to access the class by index. How can I achieve this in TypeScript?
typescript class
asked Nov 22 '18 at 20:09
Makoto EmuraMakoto Emura
116210
I want to make an array of classes in TypeScript. This is possible in vanilla JavaScript:
class A {
constructor() {console.log('constructor');}
a() {}
}
const array = [A];
new (array[0])(); // Prints 'constructor'
I want to make the array type safe using an interface. This is my attempt to implement this in TypeScript:
interface I {
a();
}
class A implements I {
constructor() {console.log('constructor')}
a() {}
}
const array: I = [A];
new (array[0])();
When I compile this, I get this error:
Error:(16, 21) TS2322: Type 'typeof A' is not assignable to type 'I'.
Property 'a' is missing in type 'typeof A'.
Because this error message mentions that typeof A is not assignable to type 'I', it seems that arrays can not contain classes, as typeof is used for instantiated objects.
What I need is a way to group all my classes in a single variable without instantiating them, and be able to access the class by index. How can I achieve this in TypeScript?
typescript class
typescript class
asked Nov 22 '18 at 20:09
Makoto EmuraMakoto Emura
116210
asked Nov 22 '18 at 20:09
Makoto EmuraMakoto Emura
116210
asked Nov 22 '18 at 20:09
Makoto EmuraMakoto Emura
116210
asked Nov 22 '18 at 20:09
Makoto EmuraMakoto Emura
116210
asked Nov 22 '18 at 20:09
Makoto EmuraMakoto Emura
116210
116210
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Interfaces define properties and method available on instances, so this would work:
const array: I = [new A()];
It's not what you want, but it should demonstrate why it's not working: Class and instance are two different things.
What you want to say is "it's an array of types and new() will return an instance of I".
I think it should look like this:
class Test implements I {
a() {}
}
interface I {
a();
}
interface TI {
new (): I;
}
const arr: TI = [Test];
const inst = new arr[0]();
answered Nov 22 '18 at 20:25
Christoph LütjenChristoph Lütjen
1,4541012
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Interfaces define properties and method available on instances, so this would work:
const array: I = [new A()];
It's not what you want, but it should demonstrate why it's not working: Class and instance are two different things.
What you want to say is "it's an array of types and new() will return an instance of I".
I think it should look like this:
class Test implements I {
a() {}
}
interface I {
a();
}
interface TI {
new (): I;
}
const arr: TI = [Test];
const inst = new arr[0]();
answered Nov 22 '18 at 20:25
Christoph LütjenChristoph Lütjen
1,4541012
add a comment |
Interfaces define properties and method available on instances, so this would work:
const array: I = [new A()];
It's not what you want, but it should demonstrate why it's not working: Class and instance are two different things.
What you want to say is "it's an array of types and new() will return an instance of I".
I think it should look like this:
class Test implements I {
a() {}
}
interface I {
a();
}
interface TI {
new (): I;
}
const arr: TI = [Test];
const inst = new arr[0]();
answered Nov 22 '18 at 20:25
Christoph LütjenChristoph Lütjen
1,4541012
add a comment |
Interfaces define properties and method available on instances, so this would work:
const array: I = [new A()];
It's not what you want, but it should demonstrate why it's not working: Class and instance are two different things.
What you want to say is "it's an array of types and new() will return an instance of I".
I think it should look like this:
class Test implements I {
a() {}
}
interface I {
a();
}
interface TI {
new (): I;
}
const arr: TI = [Test];
const inst = new arr[0]();
answered Nov 22 '18 at 20:25
Christoph LütjenChristoph Lütjen
1,4541012
Interfaces define properties and method available on instances, so this would work:
const array: I = [new A()];
It's not what you want, but it should demonstrate why it's not working: Class and instance are two different things.
What you want to say is "it's an array of types and new() will return an instance of I".
I think it should look like this:
class Test implements I {
a() {}
}
interface I {
a();
}
interface TI {
new (): I;
}
const arr: TI = [Test];
const inst = new arr[0]();
answered Nov 22 '18 at 20:25
Christoph LütjenChristoph Lütjen
1,4541012
answered Nov 22 '18 at 20:25
Christoph LütjenChristoph Lütjen
1,4541012
answered Nov 22 '18 at 20:25
Christoph LütjenChristoph Lütjen
1,4541012
answered Nov 22 '18 at 20:25
Christoph LütjenChristoph Lütjen
1,4541012
1,4541012
add a comment |
add a comment |
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