Nim lang 如何在Nim中声明可为null的字段?
Nim lang 如何在Nim中声明可为null的字段?,nim-lang,Nim Lang,stock\u符号是可选的,它只存在于一些公司,在Nim中声明它的正确方式是什么 我必须使用ref还是有其他方法 type Company = object name: string stock_symbol: string echo Company(name: "Microsoft", stock_symbol: "MSFT") echo Company(name: "Kinetic", st
stock\u符号
是可选的,它只存在于一些公司,在Nim中声明它的正确方式是什么
我必须使用ref
还是有其他方法
type
Company = object
name: string
stock_symbol: string
echo Company(name: "Microsoft", stock_symbol: "MSFT")
echo Company(name: "Kinetic", stock_symbol: nil)
和复合型类似的问题,通常你需要知道证券交易所和符号
type
SymbolWithExchange = object
exchange: string
symbol: string
Company2 = object
name: string
stock_symbol: SymbolWithExchange
echo Company2(
name: "Microsoft",
stock_symbol: SymbolWithExchange("NYSE", "MSFT")
)
echo Company2(name: "Kinetic", stock_symbol: nil)
似乎应该使用
选项[T]
import options
type
Company = object
name: string
stock_symbol: Option[string]
echo Company(name: "Microsoft", stock_symbol: some("MSFT"))
echo Company(name: "Kinetic", stock_symbol: none(string))
及
import options
type
SymbolWithExchange = object
exchange: string
symbol: string
Company2 = object
name: string
stock_symbol: Option[SymbolWithExchange]
echo Company2(
name: "Microsoft",
stock_symbol: some(SymbolWithExchange(exchange: "NYSE", symbol: "MSFT"))
)
echo Company2(name: "Kinetic", stock_symbol: none(SymbolWithExchange))