CODEWITHSUNDEEP
delphifunction-pointersdelphi-xe2
RBA
RBA

Reputation: 12584

Delphi method call followed by ()

I've encountered in some code the following call :

SQLParser.Parse(qry.SQL.Text)().GetWhereClause

and I don't understand the meaning of those 2 parenthesis after the Parse call. Following the implementation I got the declarations for each one of them:

 TSQLParser = class
  public
    class function Parse(const ASQL: string): ISmartPointer<TSQLStatement>;

  TSQLStatement = class
    function GetWhereClause: string;

and 

  ISmartPointer<T> = reference to function: T;

Upvotes: 4

Views: 430

Answers (1)

NineBerry
NineBerry

Reputation: 28509

The Parse function returns a reference to a function. You can call this function. A longer equivalent form would be:

var
  FunctionReference: ISmartPointer<TSQLStatement>;
  SQLStatement: TSQLStatement;
begin
  { Parse returns a reference to a function. Store that function reference in FunctionReference }
  FunctionReference := TSQLParser.Parse(qry.SQL.Text);
  { The referenced function returns an object. Store that object in SQLStatement }
  SQLStatement := FunctionReference();
  { Call the GetWhereClause method on the stored object }
  SQLStatement.GetWhereClause();

The line in the question is just a shorter version that does not use explicit variables to store the intermediate results.

Upvotes: 12

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