Skip to main content

Stream

Stream = TMemoryStream

Example​

procedure BuildBuffer(var Buffer: Stream);
begin
  Buffer := TMemoryStream.Create;
  try
    Buffer.Size := 0;
    // Use Buffer while it remains owned by this procedure.
  finally
    Buffer.Free;
    Buffer := nil;
  end;
end;

Usage​

Aliases TMemoryStream without allocating or copying its mutable byte buffer, cursor, size, or ownership.

Shared object state​

Assigning a Stream variable copies the object reference. Both variables then see the same heap buffer, Position, Size and mutations. Reading through one advances the cursor observed through the other; writing, clearing or resizing through one changes the same content. Use CopyFrom or a purpose-built conversion when independent bytes are required.

The actual producer controls ownership:

  • a TMemoryStream.Create result is script-owned and should be released with Free in finally;
  • a stream supplied by a host property or callback is normally borrowed unless that entry explicitly transfers it;
  • passing a stream to another object does not transfer ownership unless that operation says so; and
  • freeing one alias invalidates every other alias to the same object.

Setting a freed variable to nil reduces accidental reuse but cannot clear other aliases. A nil stream has no buffer, and a member call through it fails.

Size, encoding and failure boundaries​

The visible stream properties adapt Velox Int64 Position/Size to script LongInt. Keep script-managed memory streams below signed 32-bit limits and apply a stricter business limit to partner-controlled content. Allocation, copying and conversion can temporarily require multiple complete buffers.

The stream stores bytes, not text. Raw String-based Read/Write calls do not select an encoding or resize a destination string for the caller. Use the documented conversion helper when the bytes represent text, Base64 or another encoded format.

Mutations are not transactional or thread-safe. An exception can leave Position, Size or content partially changed. Do not share an instance across concurrent Velox work.

Additional Technical Info​

Stream is installed during every Velox script compilation with AddTypeCopyN('Stream', 'TMemoryStream'). It is compile-time-equivalent to TMemoryStream. The alias does not mean the abstract TStream ancestor, wrap an external stream, allocate a buffer or copy bytes.

Related Code Library entries

  • TMemoryStream - complete construction, cursor, allocation and method guidance.
  • Stream classes - comparison of the exposed stream implementations.

External references

Created 2026-07-15