Question

我目前正试图为一般化类别名。我使用的是typescript-collections包，想要重命名。

class Bar<T> {}
class Foo = Bar<X>;

我将如何进行第二行？

Answer 1

如果您只需要在其他地方的类型注释/提示中对Bar<X>进行别名（例如。function blah(foo: Bar<X>)），则可以使用以下语句：

type Foo = Bar<X>;

请注意，您仍然无法执行new Foo()，type语句只对TypeScript的“types”部分有贡献，而对“values”部分没有贡献（就像类一样）。

如果你想要一个真正的类，一个简单而有效的解决方案是扩展原来的Bar<X>类，如下所示：

class Foo extends Bar<X> {}

我个人并不特别喜欢这个解决方案，因为它会使你的代码不那么清晰。

Answer 2

您可以从Foo继承Bar<X>以创建预定义X类型参数的类：

class Foo extends Bar<X> {}

Answer 3

您可以使用类型别名@toskv建议：

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.Spatial;
[Table("Category")]
public partial class Category
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public Category()
    {
        Product_Category_Mapping = new HashSet<Product_Category_Mapping>();
        Discounts = new HashSet<Discount>();
    }

    public int Id { get; set; }

    [Required]
    [StringLength(400)]
    public string Name { get; set; }

    public string Description { get; set; }

    public int CategoryTemplateId { get; set; }

    [StringLength(400)]
    public string MetaKeywords { get; set; }

    public string MetaDescription { get; set; }

    [StringLength(400)]
    public string MetaTitle { get; set; }

    public int ParentCategoryId { get; set; }

    public int PictureId { get; set; }

    public int PageSize { get; set; }

    public bool AllowCustomersToSelectPageSize { get; set; }

    [StringLength(200)]
    public string PageSizeOptions { get; set; }

    [StringLength(400)]
    public string PriceRanges { get; set; }

    public bool ShowOnHomePage { get; set; }

    public bool IncludeInTopMenu { get; set; }

    public bool HasDiscountsApplied { get; set; }

    public bool SubjectToAcl { get; set; }

    public bool LimitedToStores { get; set; }

    public bool Published { get; set; }

    public bool Deleted { get; set; }

    public int DisplayOrder { get; set; }

    public DateTime CreatedOnUtc { get; set; }

    public DateTime UpdatedOnUtc { get; set; }

然后您可以将其用作类型：

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.Spatial;

[Table("Discount")]
public partial class Discount
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public Discount()
    {
        DiscountRequirements = new HashSet<DiscountRequirement>();
        DiscountUsageHistories = new HashSet<DiscountUsageHistory>();
        Categories = new HashSet<Category>();
        Products = new HashSet<Product>();
    }

    public int Id { get; set; }

    [Required]
    [StringLength(200)]
    public string Name { get; set; }

    public int DiscountTypeId { get; set; }

    public bool UsePercentage { get; set; }

    public decimal DiscountPercentage { get; set; }

    public decimal DiscountAmount { get; set; }

    public DateTime? StartDateUtc { get; set; }

    public DateTime? EndDateUtc { get; set; }

    public bool RequiresCouponCode { get; set; }

    [StringLength(100)]
    public string CouponCode { get; set; }

    public int DiscountLimitationId { get; set; }

    public int LimitationTimes { get; set; }

    public int? MaximumDiscountedQuantity { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<DiscountRequirement> DiscountRequirements { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<DiscountUsageHistory> DiscountUsageHistories { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<Category> Categories { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<Product> Products { get; set; }
}

如果您有一个接收using System; using System.Collections.Generic; using System.ComponentModel.DataAnnotations; using System.ComponentModel.DataAnnotations.Schema; using System.Data.Entity.Spatial; public partial class Product_Category_Mapping { public int Id { get; set; } public int ProductId { get; set; } public int CategoryId { get; set; } public bool IsFeaturedProduct { get; set; } public int DisplayOrder { get; set; } public virtual Category Category { get; set; } public virtual Product Product { get; set; } }实例的构造函数，那么编译器将推断出类型：

type Foo = Bar<X>;

如果您想要一个绑定到特定通用约束的新类，那么您需要执行以下操作：

let foo: Foo = new Bar<X>();

Answer 4

如果您只需要一个类型别名，那么您可以使用type来创建它：

type Foo = Bar<X>;

通过这种方式，您可以执行以下操作：

let x: Foo;

但不是：

let x= new Foo();

另一个解决方案是扩展Bar并创建一个空类。并不是你应该如何使用类层次结构，但它可以满足您的需求。

class Foos extends Bar<number> { }

广义类的打字稿别名实例

4 个答案: