Lua:什么时候可以使用冒号语法?

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问题描述

尽管我了解.和: 之间的基本基本区别，但我还没有完全了解何时Lua允许使用冒号语法.例如，类似的方法确实可以工作:

While I understand the basic difference between . and :, I haven't fully figured out when Lua allows to use the colon syntax. For instance, something like this does work:

s = "test"
-- type(s) is string.
-- so I can write a colon function for that type
function string:myFunc()
  return #self
end

-- and colon function calls are possible
s:myFunc()

但是，相同的模式似乎不适用于其他类型.例如，当我有一个table而不是string时:

However the same pattern does not seem to work for other types. For instance, when I have a table instead of a string:

t = {}
-- type(t) is table.
-- so I can write a colon function for that type
function table:myFunc()
  return #self
end

-- Surprisingly, a colon function call is not not possible!
t:myFunc() -- error: attempt to call method 'myFunc' (a nil value)
-- But the verbose dot call works
table.myFunc(t)

继续使用其他类型:

x = 1
-- type(x) is number.
-- So I was expecting that I can write a colon function
-- for that type as well. However, in this case even this
-- fails:
function number:myFunc()
  return self
end
-- error: attempt to index global 'number' (a nil value)

我目前正试图弄清这一点.结论

I'm currently trying to make sense of this. Is it correct to conclude that

某些类型(如string)允许结肠功能定义和结肠功能调用.
table之类的其他类型仅允许进行结肠功能定义，而不允许进行结肠功能调用.
还有其他类型，例如number都不允许.

certain types like string allow both colon-function-definitions and colon-function-calls.
other types like table allow only colon-function-definitions but not colon-function-calls.
yet other types like number allow neither.

这些差异的确切原因是什么?是否有所有类型的列表，显示它们支持的冒号语法类型? number案例是否有解决方法，允许编写例如x:abs()?

What exactly is the reason for these differences? Is there a list of all types, showing which type of colon-syntax they support? Is there maybe a workaround for the number case, allowing to write e.g. x:abs()?

什么时候可以使用冒号语法

问题描述

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