为什么是-compile（export_all）不好的做法？ [英] Why is -compile(export_all) bad practice?

问题描述

所有的erlang书似乎都说export_all是不好的做法，但不给出理由。最后，大多数模块花费大部分时间来编译（export_all），因为不断更新模块列表以删除帮助函数是一个麻烦。这是不好的做法，因为我应该关心我向其他开发人员公开的功能？或者是不好的做法，因为模块具有的功能数量有某种性能成本，因为可能是热代码加载的东西。如果填充一个具有很多功能的模块的性能受到打击，那么它有多糟糕？

解决方案

由于几个原因：

• 清晰度：更容易看出在模块之外使用哪些功能。

  
  
  

  当您在Erlang shell中完成标签时，您只能获得一个列表导出的功能，没有其他。当您重构模块时，您会知道哪些功能可以安全地重命名，而不需要外部用户。




• 代码气味：您收到未使用的功能的警告。 / p>
  
  

  因此，您将避免死亡代码。




• 优化：编译器可能会使更多知道不是所有功能都必须导出的积极的优化。

All the erlang books seem to say export_all is bad practice but don't give a reason. In the end most modules spend a majority of their time with compile(export_all) because constantly updating the list of modules to remove the helper functions is a hassle. Is it bad practice because I'm supposed to care about the functions I expose to other developers? Or is it bad practice because there's some kind of performance cost in the number of functions a module has, because of maybe things like hot code loading. If there is a performance hit to stuffing a module with a lot of functions, how bad is it?

解决方案

For several reasons:

• Clarity: it's easier to see which functions are intended to be used outside the module.

  When you tab complete in the Erlang shell you get a list of only the exported functions and no others. When you refactor the module, you know which functions you can safely rename without external users depending on them.

• Code smell: you get warnings for unused functions.

  Therefore you'll avoid dead code.

• Optimization: the compiler might be able to make more aggressive optimizations knowing that not all functions have to be exported.

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