我需要调用事件处理程序来告诉用户选择TCard或TLabel
然后将此值作为参数返回。
我有两个单位GAME，SS_SPELL
这就是SS_SPEll中的代码如何工作。
// TSPELL
// ======
// The chronology is:
// 1. At appropriate points in the game (such as before turn, after cast etc aka trigger points)
// the game calls the SpellMeister's RunSpells method.
// 2. RunSpells checks the database for spells matching the card that
// initiated the spell action, and the trigger point at which it did so.
// For each one that it finds it will create an appropriate object, which
// could be a TSpell descendent or a TSpellAdjuster descendent.
// For each TSpell it finds it fires off an onFindSpell event.
// See below for details of how TSpellAdjusters are handled.
// 3. The handler for the onFindSpell events can (should) call the spells'
// AimAt method for each potential target. A potential target is a card
// or a player.
// 4. A spell's AimAt method checks if the potential target is a legitimate
// target for that spell and if so it calls its ApplySpellTo method to
// actually do the dirty deed.
所以我需要的是一旦RunSpells获得db信息，它将检查needs2ndtarget：= 1，如果是，那么我知道我需要这个法术的第二个目标。
以下是TSpellBase，它是从TSpell创建的。为了创建此活动，我添加了FOnSeek2ndTarget
在私有部分和受保护的FNeed2Target和公共财产OnSeek2ndTarget。你也会看到
TTargetEvt，目前设置为TCARD，但我需要它来回复TCard或TLAbel，不知道如何做到这一点。
TTargetEvt = procedure (Card : TCard) of Object;
TSpellBase = class
private
FOnManaChange: TManaEvt;
FOnSeek2ndTarget: TTargetEvt;
protected
FCardType : TCardType;
FOriginator : TCard;
FNeed2Target : integer;
function LegitimateTarget (Candidate : TObject) : boolean; virtual;
public
constructor Create; virtual;
property CardType : TCardType read FCardType write FCardType; // ctLava, ctNature, ctWizard, etc etc
property Originator : TCard read FOriginator write FOriginator;
property Need2Target : integer read FNeed2Target write FNeed2Target;
property OnManaChange : TManaEvt read FOnManaChange write FOnManaChange;
property OnSeek2ndTarget : TTargetEvt read FonSeek2ndTarget write FOnSeek2ndTarget;
end;
现在在TSpell，我不认为我需要这里的任何东西，但它需要spellmiester.runspell程序
TSpell = class(TSpellBase)
private
protected
FCategory : TCategory;
FLifeToAdd : Byte;
FMaxRandom : Byte;
FReplaceDmg : Byte;
FReplacement : string;
FStatTarget : Byte;
FTrigger : TTrigger;
procedure ApplySpellTo(Target : TObject); virtual; abstract; // Apply the spell to the target
public
procedure AimAt(Candidate: TObject); virtual;
property Category : TCategory read FCategory write FCategory;
property LifeToAdd : Byte read FLifeToAdd write FLifeToAdd;
property MaxRandom : Byte read FMaxRandom write FMaxRandom;
property ReplaceDmg : Byte read FReplaceDmg write FReplaceDmg;
property Replacement : string read FReplacement write FReplacement;
property StatTarget : Byte read FStatTarget write FStatTarget;
property Trigger : TTrigger read FTrigger write FTrigger;
end;
这里我在私人部分添加了FOnSeek2ndTarget。和属性所以现在当一个咒语被施放时它会
到这里，现在打电话给runsspells。
TSpellMeister = class
private
FonFindSpell : TRcvSpell;
FOnManaChange : TManaEvt;
FOnSeek2ndTarget : TTargetEvt;
// FonNewAdjuster : TRcvSpell;
protected
FAdjusters : TAdjusters;
FQuery : TADOQuery;
public
constructor Create(DBCon: TADOConnection);
destructor Destroy; override;
function IfNull( const Value, Default : OleVariant ) : OleVariant;
procedure Adjust(Attacker : TCard; Victim : TObject; var TheDamage : integer); overload;
procedure Adjust(Attacker : TCard; var TheCost : integer); overload;
procedure RunSpells(Card : TCard; Trigger : TTrigger);
property onFindSpell : TRcvSpell read FonFindSpell write FonFindSpell;
property OnManaChange : TManaEvt read FOnManaChange write FOnManaChange;
property OnSeek2ndTarget: TTargetEvt read FOnSeek2ndTarget write FOnSeek2ndTarget;
// property onNewAdjuster : TRcvSpell read FonNewAdjuster write FonNewAdjuster;
end;
这就是问题所在，我添加foundspell.Need2ndTarget这会从数据库中获取数据（如果是1）则需要用户选择该法术的另一个目标。目前我添加了
如果FoundSpell.Need2Target = 1那么 FOnSeek2ndTarget（卡）;
但我确信这不正确......
//**************************************************************************
procedure TSpellMeister.RunSpells(Card: TCard; Trigger: TTrigger);
//**************************************************************************
var
OneSpell : TSpellBase;
FoundSpell : TSpell; // Just so only have to cast once
begin
assert(assigned(FonFindSpell),'TSpellMeister.RunSpells : No onFindSpell event handler!');
// Search the database
FQuery.Active := FALSE;
FQuery.Parameters.ParamByName(SQL_PARAM_SPELL_ORIGINATOR).Value := Card.CName;
FQuery.Parameters.ParamByName(SQL_PARAM_SPELL_TRIGGER ).Value := Trigger;
FQuery.Active := TRUE;
// Iterate through the spell records. For each one, create a category-specific
// TSpell descendant and fire off an onFindSpell event.
if FQuery.RecordCount > 0 then
begin
FQuery.Recordset.MoveFirst;
while not FQuery.Recordset.EOF do
begin
case TCategory(FQuery.Recordset.Fields[DB_FLD_CATEGORY].Value) of
caAboveLife : OneSpell := TSpellAboveLife.Create;
caDamage : OneSpell := TSpellDamage.Create;
caDamagePlus : OneSpell := TSpellDamagePlus.Create;
caDamagePlusPercent : OneSpell := TSpellDamagePlusPercent.Create;
caDamagePercentIncrease : OneSpell := TSpellDamagePercentIncrease.Create;
caDamagePercentDecrease : OneSpell := TSpellDamagePercentDecrease.Create;
caDamageSpells : OneSpell := TSpellDamageSpells.Create;
caDestroy : OneSpell := TSpellDestroy.Create;
.....
else raise ERangeError.CreateFmt(ERROR_INVALID_DB_NUMBER,[DB_FLD_CATEGORY,FQuery.Recordset.Fields[DB_FLD_CATEGORY].Value]);
end;
try
if assigned(OneSpell) then
begin
OneSpell.CardType := TCardType (IfNull( FQuery.Recordset.Fields[ DB_FLD_CARD_TYPE ].Value,0) );
OneSpell.Originator := Card;
OneSpell.OnManaChange := Self.OnManaChange;
OneSpell.OnSeek2ndTarget := self.OnSeek2ndTarget;
assert(OneSpell.Originator.COwner is TPlayer,'TSpellMeister.RunSpells : OneSpell.Originator.COwner not a player: ' + OneSpell.Originator.COwner.ClassName);
try
FoundSpell := TSpell(OneSpell);
FoundSpell.Originator := Card;
FoundSpell.Trigger := Trigger;
FoundSpell.CardType := TCardType ( FQuery.Recordset.Fields[ DB_FLD_CARD_TYPE ].Value );
FoundSpell.Category := TCategory ( FQuery.Recordset.Fields[ DB_FLD_CATEGORY ].Value );
FoundSpell.LifeToAdd := IfNull( FQuery.Recordset.Fields[ DB_FLD_LIFE_TO_ADD ].Value,0);
FoundSpell.MaxRandom := IfNull( FQuery.Recordset.Fields[ DB_FLD_MAX_RANDOM ].Value,0);
FoundSpell.PerCent := IfNull( FQuery.Recordset.Fields[ DB_FLD_PER_CENT ].Value,0);
FoundSpell.Plus := IfNull( FQuery.Recordset.Fields[ DB_FLD_PLUS ].Value,0);
FoundSpell.ReplaceDmg := IfNull( FQuery.Recordset.Fields[ DB_FLD_REPLACE_DMG ].Value,0);
FoundSpell.Replacement := IfNull( FQuery.Recordset.Fields[ DB_FLD_REPLACEMENT ].Value,0);
FoundSpell.StatTarget := IfNull( FQuery.Recordset.Fields[ DB_FLD_STAT_TARGET ].Value,0);
FoundSpell.Target := TTargetType( IfNull(FQuery.Recordset.Fields[ DB_FLD_TARGET ].Value,0) );
FoundSpell.Need2Target := IfNull( FQuery.Recordset.Fields[ DB_FLD_NEED2TARGET ].Value,0);
assert(FoundSpell.Originator.COwner is TPlayer,'TSpellMeister.RunSpells : FoundSpell.Originator.COwner not a player: ' + OneSpell.Originator.COwner.ClassName);
if FoundSpell.Need2Target = 1 then
FOnSeek2ndTarget(Card);
FonFindSpell(FoundSpell);
finally
FreeAndNil(OneSpell);
end;
end;
except // I think this is OK but is there a possible bug if
FreeAndNil(OneSpell); // spell adjuster added to list then destroyed?
end; // List item would then be invalid.
FQuery.Recordset.MoveNext;
end;
end;
end;
所以这就是ss_spells单元，现在是使用ss_spells单元的game单元
在forum.create我有
FSpellMeister.OnSeek2ndTarget := self.Handle2ndTarget;
不知道在Handle2ndTarget中放入什么只是
//****************************************************************************
procedure TFGame.Handle2ndTarget(Card : TCard);
begin
showmessage('Select a target HANDLE2ndTARGET');
end;
看看我是否至少能够到达这里..
因此，如果您无法解决这个问题，那么当foundspell.Need2ndTarget := 1使用事件FOnSeek2ndTarget();
答案 0 :(得分：4)
只需更改TTargetEvt类型的签名，例如：
TTargetEvt = procedure (Card : TCard; var Target: TObject) of Object;
然后相应地更新RunSpells()：
var
Target: TObject;
...
if FoundSpell.Need2Target = 1 then
begin
Target := nil;
if Assigned(FOnSeek2ndTarget) then FOnSeek2ndTarget(Card, Target);
// use Target as needed...
end;
...
然后相应地更新您的处理程序：
procedure TFGame.Handle2ndTarget(Card : TCard; var Target: TObject);
begin
Target := ...;
end;
答案 1 :(得分：2)
我需要知道如何使用事件来返回
var参数。
像这样定义您的活动：
type
TMyEvent = procedure(var ReturnValue: Integer) of object;
然后以通常的方式添加事件属性：
....
private
FOnMyEvent: TMyEvent;
....
published
property OnMyEvent: TMyEvent read FOnMyEvent write FOnMyEvent;
....
细微差别在于你如何展示事件。通常，如果您正在编写提供事件的组件，则必须满足不会在事件中附加处理程序的可能性。如果事件是为了返回一个值，那么你怎么能没有犯规者，也没有返回值？诀窍是在展示事件之前将参数指定为默认值。例如：
procedure TMyComponent.DoMyEvent(out ReturnValue: Integer);
begin
Result := DefaultValueForMyEventHandler;// you supply something meaningful here
if Assigned(FOnMyEvent) then
FOnMyEvent(Result);
end;
因此，如果组件的使用者没有为事件提供处理程序，那么该方法仍然会产生合理的值。
如果您阅读此内容并认为FOnMyEvent nil没有任何意义，那么您的设计是错误的。如果要强制使用者提供行为，而不允许依赖于默认值，则事件是错误的机制。在这种情况下，要求消费者通过参数提供行为，可能由组件构造函数的签名强制执行。或者其他一些方式。
我刚给你一个与你的代码无关的基本示例。我试图了解这些概念。希望您能够根据您的特定需求进行调整。