path class

#install.packages(here)
#install.packages(crayon)

p <- function(str){
  structure(str,class=c("path","character"))
}

`/.path` <- function(a,b){
  p(paste(a,b,sep="/"))
}

print.path <- function(x){
  header <- "<object of class path, which does"
  if(path_exists(x)){
    header <- crayon::green(paste(header,"exist>\n"))
  } else {
    header <- crayon::red(paste(header,"not exist yet>\n"))
  }
  cat(header)
  cat(x,"\n")
}

path_exists <- function(x){
  if(!inherits(x,"path"))
    stop("x is not of class 'path'",call.=F)
  file.exists(here::here(x))
}

path_create <- function(x,dir=F,warn=T){
  if(path_exists(x)){
    if(warn)
      warning(paste0("Path '",x,"' already exists"),call.=F)
  } else {
    if(dir){
      invisible(dir.create(x,recursive = T))
    } else {
      path_create(path(dirname(x)),dir=T,warn=F)
      invisible(file.create(x))
    }
  }
}





#As long as one of the elements is a path class, it works
p1 <- p("folder one")
p2 <- p1 / "folder two"
p3 <- "folder three" / p("folder four") / "Test text2.txt"
p1 #Tells us that it doesn't exist
path_exists(p1) #FALSE - Because we've not made it yet
path_create(p2,dir=T) #Creates the path as a directory
path_create(p2,dir=T) #Warns that it already exists
path_exists(p1) #TRUE - because this now exists
path_exists(p2) #TRUE - As does this
p2 #This now exists
p3 #This doesn't
writeLines("Testing",p3) # Error because the directory doesn't exist
path_create(p3) #Create this file
path_exists(p3) #TRUE - It does exist
writeLines("Testing",p3) #No Error because it exists now
readLines(p3) #Read it back to check
p3

p(paste(a,b,sep="/")) => p(file.path(a,b)) this makes it cross-platform