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DirectoryExists

Function DirectoryExists( const Directory : string) : Boolean

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := DirectoryExists('C:\Fictional\Inbound');
end;

Usage​

DirectoryExists reports whether a path resolves to an existing directory using Velox's default link-following behaviour.

Parameters

NameTypeDescription
Directorystring, constAbsolute or relative directory path to query. No environment-variable expansion or path normalisation is performed.

Returns

True when the path exists and object is a directory; otherwise False.

Behaviour

  • A normal accessible directory returns True.
  • A regular file, nonexistent path or broken followed link returns False.
  • A relative value is resolved against the Velox process current directory, not the location of the current configuration or source file.
  • The function observes only the state at the time of the call; it does not reserve, open or lock the directory.

Errors

Normal missing, inaccessible and wrong-kind cases return False. Values that cannot convert to string and unexpected runtime failures can still raise before or during the call.

Usage notes

Prefer approved absolute paths in service configurations. When the next operation must create the directory, call ForceDirectories and check its result rather than relying on a separate existence check.

Additional Technical Info​

DirectoryExists returns whether Directory currently resolves to an existing directory. The script exposes only one argument, so the underlying Delphi routine's FollowLink option always uses its default value of True.

The example uses a fictional path. It is source-reviewed and was not executed by the documentation workflow.

Implementation

The PascalScript registration calls SysUtilsImport.DirectoryExists, which delegates to installed System.SysUtils.DirectoryExists(Directory). The omitted FollowLink parameter defaults to True. On Windows, the current RTL reads file attributes and, for a reparse/symbolic-link path, opens it with directory backup semantics to verify the followed target before accepting the directory attribute.

Edge cases and quirks

  • Scripts cannot request FollowLink=False. A link to an existing directory is therefore tested through its target, and a broken link returns False.
  • False can mean missing, not a directory, inaccessible, invalid or unable to open the reparse target. The signature exposes no reason.
  • Access and sharing rules can make a path appear unavailable even when another security context can use it.
  • The process current directory is shared state. Relative checks can be unreliable if another component changes it; ProcessPath temporarily does exactly that.
  • Existence can change immediately after the return. Use the result for branching and diagnostics, not as an authorisation or concurrency guarantee.

Side effects

No persistent file-system change is made. The Windows implementation can briefly open a handle while following a reparse point.

Performance and concurrency

This is an operating-system metadata query and can block on remote or unavailable storage. It is safe to call concurrently, but its answer is a non-atomic snapshot and does not synchronise later operations.

Related entries

External references

Created 2026-07-15