Ada中的自定义“图片”属性？ [英] Custom 'image attribute in Ada?

问题描述

所以我有事。

type Thing is new record
  ...elements...
end record;

我有一个将其字符串化的函数。

I have a function which stringifies it.

function ToString(t: Thing) returns string;

我想告诉Ada将此功能用于 'image ，这样我图书馆的用户就不必考虑使用的是内置类型还是Thing。

I would like to be able to tell Ada to use this function for Thing'image, so that users of my library don't have to think about whether they're using a builtin type or a Thing.

但是，显而易见的语法是：

However, the obvious syntax:

for Thing'image use ToString;

...不起作用。

有没有办法做到这一点？

Is there a way to do this?

推荐答案

我不知道为什么语言不支持此功能，并且我不知道是否有人提出过正式建议（Ada Issue或AI）。 AI12-0020 （Ada 2012的第20条AI）中提到我不认为我们出于技术原因而拒绝它的重要性。

I don’t know why the language doesn’t support this, and I don’t know whether anyone has ever raised a formal proposal that it should (an Ada Issue or AI). The somewhat-related AI12-0020 (the 20th AI for Ada 2012) includes the remark "I don't think we rejected it for technical reasons as much as importance".

您可以看到为什么Ada报告员小组可能认为这相对不重要：您始终可以声明 Image 函数；

You can see why the Ada Rapporteur Group might think this was relatively unimportant: you can always declare an Image function; the difference between

Pkg.Image (V);

和

Pkg.Typ’Image (V);

不是很大。

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