是否可以暂时重命名和阻止内置函数? [英] Is it possible to rename and block built-in functions temporarily?

问题描述

我想临时重命名一个内置符号并使用不同的名称，同时阻止该符号的主名称.例如，我希望下面的代码只打印2"而不是1"和3":

I wish to temporarily rename a built-in symbol and use it with different name while block the main name of this symbol. For example, I wish the following code to print only "2" but not "1" and "3":

Block[{print = Print, Print}, Print[1]; print[2]; Print[3];]

实际上，上面的代码没有打印任何内容.

In really the above code prints nothing.

是否可以让 print 在这样的代码中工作而完全阻止符号 Print?

Is it possible to make print working inside such code while completely block symbol Print?

类似的解决方案

With[{Print = f, print = Print}, Print[1]; print[2]; Print[3];] 

不适合，因为 Print 在此类代码中并未真正被阻止.

are not suitable since Print is not really blocked inside such code.

问题出现时思考一种禁用跟踪的方法消息内部.

The question appeared while thinking on a way to disable tracing of Message internals.

推荐答案

这不是很干净，但我相信它是有用的.

This is not very clean, but I believe it is serviceable.

Internal`InheritedBlock[{Print},
  Unprotect[Print];
  Print[x__] := Null /; ! TrueQ[$prn];
  print[x__] := Block[{$prn = True}, Print[x]];
  Print[1]; print[2]; Print[3];
]

<小时>

如果在返回中将函数替换为 Null 是不可接受的，您可能需要使用类似的东西:

---

If it is not acceptable to have the function replaced with Null in the return, you may need to use something like:

func[x__] := Hold[func[x]] /; ! TrueQ[$prn];

在块之后是 ReleaseHold.

或者:

func[x__] := zz[x] /; ! TrueQ[$prn];

然后跟随块:/.z->函数

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