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

问题描述

所以我有件事.

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

我有一个字符串化它的函数.

I have a function which stringifies it.

function ToString(t: Thing) returns string;

我希望能够告诉 Ada 将此函数用于 Thing'image，这样我的库的用户就不必考虑他们使用的是内置类型还是一件事.

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，明显的语法:

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这个，我不知道是否有人提出过正式的建议，它应该(一个Ada 问题或 AI).有点相关的AI12-0020(Ada 2012 的第 20 届 AI)包括我认为我们拒绝它的原因不是技术原因，而是重要性".

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 Rapporteur Group 可能认为这相对不重要:您总是可以声明一个 Image 函数；之间的区别

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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