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H2219 Private symbol '%s' declared but never used (Delphi)

例如
private
x:boolean; //是否存在某种方法关闭针对定义x的H2219提示
y:boolean;
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z@S7

作者：

1111111113 (1111111113)	▲△△△△	-
	普通会员

2022/9/24 21:09:32

1楼：

如果只有2个bo
建议用一个整数或者 byte 代替
代码用
case 来区别 xy同时存在不同时存在的情况
8bit 每次取4bit 也就只要写15种不同的开关代码执行
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-

作者：

emailx45 (emailx45)	▲▲▲▲△	-
	普通会员

2022/9/24 22:27:38

2楼：

easy way to avoid "Hints" message is:

type
{$HINTS OFF}
  TMyClass = class
  private
    FBoo: boolean;
  public
  end;
{$HINTS ON}

...
var
  Form1: TForm1;

implementation

{$R *.dfm}
//
// NOTE: before and after procedure/function!  NOT on "block of code" into procedure/function!!!
//
// ---> Hints it's NOT an "error"!!! it just ask you to review your code to do better!!!
//
{ ...$WARNINGS OFF } // to avoid show "WARNINGS"

{$HINTS OFF } // to avoid show "HINTS"
procedure TForm1.Button1Click(Sender: TObject);
var
  MyVarEmptyAndDontUsed: boolean;
begin

end;
{$HINTS ON }
{ ...$WARNINGS ON }

procedure TForm1.FormCreate(Sender: TObject);
var
  MyNewVarDontUsed: boolean;
begin
  Caption := Self.Name;
end;

end.

----------
the good sense said:
--- if not necessary, then why have it?
----------------------------------------------
The higher the degree, the greater the respect given to the humblest!RAD 11.3

作者：

zhyhero (zhyhero)	★☆☆☆☆	-
	盒子活跃会员

2022/9/24 23:24:34

3楼：

@emailx45 thanks

  TMyType1 = record
  private
    Data: string;
    {$HINTS OFF}
    fish: boolean;
    small: boolean;
    river: boolean;
    {$HINTS On}
  public

  end;

  TMyType2 = record
  private
    Data: string;
    {$HINTS OFF}
    cat: boolean;
    white: boolean;
    {$HINTS On}
  public

  end;

  fld: TRttiField;
  isfish := fld.FieldType.GetField('fish') <> nil;
  issmall := fld.FieldType.GetField('small') <> nil;
  isriver := fld.FieldType.GetField('river') <> nil;
  iscat := fld.FieldType.GetField('cat') <> nil;
  iswhite := fld.FieldType.GetField('white') <> nil;

瞎想出来的一个用法，只有定义，用RTTI测试是否存在某个定义，所以编译器和IDE的H2219就成了扰乱信息了。
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z@S7

作者：

emailx45 (emailx45)	▲▲▲▲△	-
	普通会员

2022/9/25 8:25:42

4楼：

any way, a "Field"/var with "unknow value / without value" is always dangerous in critical/specific situations!

that way, it's good dont have it defined or use any other way to define it or not! == if "X-situation" then "define A", else, "define B"
----------------------------------------------
The higher the degree, the greater the respect given to the humblest!RAD 11.3

作者：

zhyhero (zhyhero)	★☆☆☆☆	-
	盒子活跃会员

2022/9/25 8:52:00

5楼：

我尝试把这种方法用在，针对Record类型的检测或推断(examine or infer)中，
尤其是只知道类型，而没有具体实例的时候。
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z@S7

作者：

emailx45 (emailx45)	▲▲▲▲△	-
	普通会员

2022/9/25 10:15:44

6楼：

well, then you can try use this:

Record with variant-parts!

type
  TMyEnums = (meOne, meTwo, etc...);

  TRec = record
    ... fields regular
  case FieldXX : TMyEnums of
    meOne: ( fieldA:double ); // "field : type managed" see help to "records"
    meTwo : ( fieldB: double);
  end;

Note: the "variant-parts" can use distinct type, but you need know like use it on client-code
---------
  case FieldXX : TMyEnums of
    meOne: ( fieldA:double ); // "field : type managed" see help to "records"
    meTwo : ( fieldB: integer ); // OK = double and integer can works in general!
---------

FieldA and FieldB using same address on memory to assign its value, then, in fact, you'll have just "ONE" field.

ex.
var
  MyRec : TRec;
begin
  MyRec.FieldXX := meOne;
  MyRec.FieldA := 10.0;
  //
  MyRec.FieldXX := meTwo;
  MyRec.FieldB := 14.00;

  MyRec.FieldA value = MyRec.FieldB value because, in fact, it's the same memory position to store the values (10.0 and 14.00), and the end, just "14.0" value will stay stored!

  MyRec.FieldA = 14.0 / MyRec.FieldB = 14.00

  "1" memory, to 2 possibilities on the context of programmer, just!

no hints :)
----------------------------------------------
The higher the degree, the greater the respect given to the humblest!RAD 11.3

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