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TFileName

TFileName = String

Example​

procedure GetLeafName(const Path: TFileName; var Leaf: String);
begin
  Leaf := ExtractFileName(Path);
end;

Usage​

TFileName names a Unicode String intended for a file path while adding no normalization, existence, access, or security guarantee.

Path interpretation belongs to the operation​

Whether text names a file, directory, URL, mask or non-filesystem identifier is determined by the receiving function. The alias does not:

  • make a relative path absolute or anchor it to a Velox folder;
  • expand environment variables or Velox tags;
  • normalize ./.., separators, casing, Unicode or a UNC/device prefix;
  • test existence, file-versus-directory kind, sharing state or permissions;
  • follow or reject symbolic links and Windows reparse points;
  • reserve the path against a create/delete/replace race; or
  • grant the service account access.

Some extraction helpers only split text and perform no I/O. File functions execute under the running Designer/service account and have their own sharing, overwrite, encoding, error and side-effect contracts. Read the exact operation page rather than inferring behavior from this parameter type.

Security guidance​

For partner-controlled names, define an allowed root and operation-specific extension/name policy. Resolve or construct the candidate with an approved helper, then verify that the effective destination remains under the allowed root. Be aware that text-only prefix checks can be defeated by .., alternate separators, case rules, UNC/device forms, reparse points and time-of-check/time-of-use races.

Do not log full paths when they can contain customer identifiers, credentials, temporary secrets or private directory structure. An empty value is not automatically the current directory; its meaning is operation-specific and can be destructive if treated as a default.

Additional Technical Info​

The SysUtils type importer registers TFileName as the normal PascalScript String. The current String is a managed UnicodeString. TFileName communicates intent to a reader and matches Delphi declarations; it does not create a distinct runtime representation or automatically call any path routine.

Assignment and parameter passing use normal managed-string behavior. A value can be empty and can contain relative segments, mixed separators, wildcard characters, reserved device names, embedded NUL, invalid filesystem characters or text longer than a target API accepts. The alias validates none of these.

Related Code Library entries

  • String - exact managed Unicode representation.
  • File functions - operation-specific path parsing, I/O, side effects and failure behavior.
  • ExtractFileName - text-only leaf-name extraction used in the example.

External references

Created 2026-07-15