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Assignment (':=') expected

Velox reports this error when a statement has produced a writable target but the compiler cannot find the := token that starts an assignment. It is a compile-time syntax error; the script does not run.

Required syntax​

Target := Expression;

Pascal uses := to store a value and = to compare two values or separate parts of some declarations. They are not interchangeable.

Example​

This statement uses an equality token where assignment is required:

procedure ScriptEvent(var Value: Variant);
begin
  Value = 'Ready'; // Error: Assignment (':=') expected
end;

Use the assignment token:

procedure ScriptEvent(var Value: Variant);
begin
  Value := 'Ready';
end;

The same diagnostic applies to the initial assignment in a for statement:

for Index = 1 to 10 do       // Incorrect
for Index := 1 to 10 do      // Correct

How Velox detects it​

Velox uses its modified PascalScript compiler. ProcessIdentifier emits this diagnostic when an identifier statement resolves to a writable value but is not followed by :=. ProcessFor emits it independently after the loop-control variable. The compiler records the current parser position, module, severity and message, then Velox displays the formatted result as [Error] Module(Row:Column): Assignment (':=') expected.

The row and column identify the token at which the parser established that := was absent. Inspect the complete statement immediately before that position, not only the highlighted token.

Common causes​

  • Using = because the intended operation is described as “set” or “equals”.
  • Omitting the colon and writing Target = Value or Target Value.
  • Starting a line with a writable identifier when a function call was intended.
  • Writing a C-style compound assignment such as Count += 1; Velox scripts require Count := Count + 1.
  • Omitting := after the counter in a for statement.
  • Leaving an earlier expression or delimiter incomplete, causing the next identifier to be interpreted as a new assignment statement.

Correction procedure​

  1. Identify whether the line is intended to change a value or compare values.
  2. For storage, use a writable variable, field, property or indexed target followed by :=.
  3. For comparison, put the = expression inside a construct that consumes a Boolean value, such as if Left = Right then.
  4. If the line already contains :=, check the preceding line for a missing semicolon, parenthesis or block terminator.
  5. Recompile and address the first remaining diagnostic before interpreting later messages.
  • Assignment — writable targets, conversion and side-effect rules.
  • Relational (Comparison) — using = and <> to produce Boolean results.
  • for loop — the required loop-control assignment form.

External references​