Title here
Summary here
File Paths in Erlang
In Erlang, we don’t have a direct equivalent to the filepath module, but we can use the filename module to handle file paths in a portable way. Here’s how we can achieve similar functionality:
-module(file_paths).
-export([main/0]).
main() ->
% Join should be used to construct paths in a portable way.
% It takes any number of arguments and constructs a hierarchical path from them.
P = filename:join(["dir1", "dir2", "filename"]),
io:format("p: ~p~n", [P]),
% You should always use join instead of concatenating separators manually.
% In addition to providing portability, join will also normalize paths.
io:format("~p~n", [filename:join("dir1//", "filename")]),
io:format("~p~n", [filename:join("dir1/../dir1", "filename")]),
% dirname and basename can be used to split a path to the
% directory and the file.
io:format("Dir(p): ~p~n", [filename:dirname(P)]),
io:format("Base(p): ~p~n", [filename:basename(P)]),
% We can check whether a path is absolute.
io:format("~p~n", [filename:pathtype("dir/file")]),
io:format("~p~n", [filename:pathtype("/dir/file")]),
Filename = "config.json",
% Some file names have extensions following a dot.
% We can split the extension out of such names with extension.
Ext = filename:extension(Filename),
io:format("~p~n", [Ext]),
% To find the file's name with the extension removed,
% use filename:rootname.
io:format("~p~n", [filename:rootname(Filename)]),
% relative_to finds a relative path between a base and a target.
% It returns an error if the target cannot be made relative to base.
case filename:relative_to("a/b/t/file", "a/b") of
{ok, Rel} -> io:format("~p~n", [Rel]);
{error, _} -> io:format("Error in relative_to~n")
end,
case filename:relative_to("a/c/t/file", "a/b") of
{ok, Rel2} -> io:format("~p~n", [Rel2]);
{error, _} -> io:format("Error in relative_to~n")
end.To run this program, save it as file_paths.erl and use the Erlang shell:
$ erl
1> c(file_paths).
{ok,file_paths}
2> file_paths:main().
p: "dir1/dir2/filename"
"dir1/filename"
"dir1/filename"
Dir(p): "dir1/dir2"
Base(p): "filename"
relative
absolute
".json"
"config"
"t/file"
Error in relative_toNote that Erlang’s filename module handles paths slightly differently from Go’s filepath:
filename:pathtype/1returnsrelative,absolute, orvolumerelativeinstead of a boolean.filename:relative_to/2is used instead ofRel, and it returns{ok, RelativePath}or{error, Reason}.- Erlang doesn’t have a direct equivalent to
strings.TrimSuffix, butfilename:rootname/1achieves the same result for file extensions.
These differences reflect the unique characteristics and conventions of Erlang compared to Go, while still providing similar file path manipulation capabilities.