你如何格式化多行 R 包消息？

Question

在开发 R 包时，我想使用R'smessage()或warning()函数为我的包用户生成输出。

有时这些消息可能很长。我可以做到这一点（文字只是一个简单的例子）：

message("If you got to this point in the code, it means the matrix was empty. Calculation continues but you should consider re-evaluating an earlier step in the process")

太棒了……但是为了风格，我也希望我的代码行少于 80 个字符，这样它们就可以很好地适应窄屏、GitHub 等。然后我可以使用 IDE 代码重排工具轻松地重新格式化我的消息如果它改变。

所以我试试这个：

message("If you got to this point in the code, it means 
the matrix was empty. Calculation continues but you should consider
 re-evaluating an earlier step in the process")

这解决了我的代码标准——它少于 80 个字符行并且可以按预期回流。但这在我的消息输出中保留了空格，我也不想要：

If you got to this point in the code, it means 
the matrix was empty. Calculation continues but you should consider
 re-evaluating an earlier step in the process

所以我发现这个方便的函数调用strwrap()似乎解决了这个问题：

message(strwrap("If you got to this point in the code, it means 
the matrix was empty. Calculation continues but you should consider
 re-evaluating an earlier step in the process"))

输出：

If you got to this point in the code, it means the matrix was empty. 
Calculation continues but you should considerre-evaluating an earlier 
step in the process

看起来不错——但它消除了“考虑”和“重新评估”之间的空间，因为该空间位于换行符处。

另一种选择是在代码中将其分解为多个块：

message("If you got to this point in the code, it means ", 
"the matrix was empty. Calculation continues but you should consider ",
"re-evaluating an earlier step in the process")

这使输出看起来正确，但文本不能再使用 IDE 等轻松回流，因为它不是一个字符串，所以这在开发方面对我不起作用。

那么：如何制作格式良好的消息，让我轻松地跨行编写消息？

我写了这个函数：

.nicemsg = function(...) {
    message(paste(strwrap(...), collapse="\n"))
}

有没有更好的方法使用内置函数，这样我就不必在我编写的每个 R 包中都包含这个函数？

Answer 1

使用更多的参数 fromstrwrap使这成为可能

message(strwrap(..., prefix = " ", initial = ""))

您可以通过调整参数的顺序来提高可读性。我不确定这是否更好。

message(strwrap(prefix = " ", initial = "", 
  "If you got to this point in the code, it means 
the matrix was empty. Calculation continues but you should consider
 re-evaluating an earlier step in the process"))

或者，如果您更喜欢包装它

tidymess <- function(..., prefix = " ", initial = ""){
  message(strwrap(..., prefix = prefix, initial = initial))
}