Delphi：记录构造函数vs工厂函数 [英] Delphi: Record constructor vs factory function

问题描述

那么初始化记录的首选方式是什么？

So what will be the preferred way of initializing records?

使用工厂函数：

TMyRecord = record
  valueX: integer;
  valueY: integer;
end;

function MyRecord(const AValueX, AValueY: integer): TMyRecord;
begin
  result.valueX := AValueX;
  result.valueY := AValueY;
end;

var
  myrec: TMyRecord;
begin
  myrec := MyRecord(1, 2);
end;

或构造函数：

TMyRecord = record
  valueX: integer;
  valueY: integer;
  constructor Create(const AValueX, AValueY: integer);
end;

constructor TMyRecord.Create(const AValueX, AValueY: integer);
begin
  self.valueX := AValueX;
  self.valueY := AValueY;
end;

var
  myrec: TMyRecord;
begin
  myrec := TMyRecord.Create(1, 2);
end;

我觉得构造函数更加封装，但是在读取代码时很容易弄错。它使它看起来像一个缺少免费电话的课程。还有更多的是输入...

I feel that the constructor things more encapsulated, but it makes it easy to get confused when reading code. It makes it look like a class that lack a call to free. It's also more to type...

为什么你比较喜欢一个？

Why would you prefer one over the other?

推荐答案

我更喜欢类，但是如果我必须使用记录，我喜欢把它们尽可能地类似于类。所以我使用记录构造函数。

I prefer classes, but if I have to use records, I like to treat them as similar as classes as possible. So I use the record constructor.

但是有一个令人讨厌的错误记录和单位。如果函数返回一个记录（使用方法），如果要访问这些方法，则会产生一个内部错误。您可以通过将其分配给另一个变量来规避：

But there is an annoying bug with records and units. If a function returns a record (with methods), it produces an internal error if you want to access these methods. You can circumvent this by assigning it to another variable:

type 
  TMyRec = record
    ..
    procedure X;
  end;


function GetRec: TMyRec;



procedure Test;
var
  r1, r2 : TMyRec;
begin
  r1 := GetRec;
  r1.X; // internal error
  r2 := r1;
  r2.X; // No internal error;

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