locks attributes for combination

attribute_lock

attribute_lock <- function(x){
  if(inherits(x,"attribute_lock")){
    x
  } else {
    ocl <- attr(x,"class")
    ncl <- if(!is.null(ocl)) c("attribute_lock",ocl) else "attribute_lock"
    structure(x,class=ncl)
  }
}

attribute_unlock <- function(x){
  structure(x,class=setdiff(attr(x,"class"),"attribute_lock"))
}

print.attribute_lock <- function(x,...){
  cat(crayon::green("<attributes locked>\n"))
  print(attribute_unlock(x))
}

c.attribute_lock <- function(...){
  dots <- list(...)
  dots_unlock <- lapply(dots,attribute_unlock)
  out <- do.call(c,dots_unlock)
  nms <- names(out)
  lens <- rep(1:...length(),
              vapply(dots_unlock,length,numeric(1)))
  
  
  for(i in seq_along(dots_unlock)){
    names(dots_unlock[[i]]) <- NULL
  }
  
  for(i in seq_along(out)){
    attributes(out[[i]]) <- attributes(dots_unlock[[lens[i]]])
    names(out[[i]]) <- nms[[i]]
  
  }
  
  attribute_lock(out)
}

str.attribute_lock <- function(x,...){
  str(attribute_unlock(x))
}


x <- structure(list(x1 = 1), "attr" = 2)
y <- structure(list(y1 = 3), "attr" = 1)

x <- attribute_lock(x)
y <- attribute_lock(y)

res <- c(x,y)

str(res)

z <- structure(list(a=1,b=2),"attr" = 3,"attr2" = c(1,2))

res <- c(x,y,z)
str(res)