相关疑难解决方法(0)

这是代码:

mf = function(..., expr) {
    expr = substitute(expr)
    print(class(expr))
    print(str(expr))
    expr
}
mf(a = 1, b = 2, expr = {matrix(NA, 4, 4)})

输出:

[1] "{"
length 2 {  matrix(NA, 4, 4) }
 - attr(*, "srcref")=List of 2
  ..$ :Class 'srcref'  atomic [1:8] 1 25 1 25 25 25 1 1
  .. .. ..- attr(*, "srcfile")=Classes 'srcfilecopy', 'srcfile' <environment: 0x7fbcdbce3860> 
  ..$ :Class 'srcref'  atomic [1:8] 1 26 1 41 26 41 1 1
  .. .. ..- attr(*, "srcfile")=Classes 'srcfilecopy', …