Filenames

Filenames are handled more strictly in Idio than many other languages. The Idio source code is expected to be encoded in UTF-8 and correspondingly, the strings-as-filenames passed to functions will be UTF-8 encoded strings.

Filenames in Unix-oriented filesystems have no encoding whatsoever, they are simple arrays of bytes (excluding ASCII NUL) and using / as a directory separator.

Any filename retrieved from the operating system will be tagged as a pathname, a variant of strings. A pathname and a string are not the same and will fail equivalence tests.

That’s inconvenient so there are some facilities to construct pathnames from Idio strings:

  • %P"..." constructs a pathname-tagged string using the same escape codes available to strings

  • string->pathname will return a pathname-tagged string from the string passed as an argument

file-names.idio
fn := "words.txt"
pn := string->pathname fn

ofh := open-output-file fn
hprintf ofh "this is contents\n"
close-handle ofh

files := glob "*.txt"
for file in files {
  puts "File: "
  write file                         ; prints %P"..." rather than ...
  (newline)

  printf "equal? %s? %s\n" fn (equal? file fn)
  printf "equal? %s? %s\n" pn (equal? file pn)
}

$ idio file-names
File: %P"words.txt"
equal? words.txt? #f
equal? words.txt? #t

Note that the printed representation of fn and pn are the same. Had we used write to get the reader-friendly representation we’d have seen the difference. The predicate pathname? may be useful.

Last built at 2024-12-21T07:11:30Z+0000 from 77077af (dev) for Idio 0.3