如何理解 MQL4 自定义指标中的 EMPTY_VALUE？
MQL4 的惯例是不向CustomIndicator/从柱绘制/显示-线段，其中CustomIndicator-storageBuffer 包含一个特别识别的“ Empty_Value ” == { EMPTY_VALUE | a value pre-set via SetIndexEmptyValue() }。
默认情况下，“ Empty_Value ”是EMPTY_VALUE.
关键步骤是这个技巧：
if ( main5 < signal5
&& Low[0] < ma5
){
ExtMapBuffer2[i] = ( ( Close[i+1] + Close[i] ) / 2 ); // .CALC/.STO
values = MAIN_UNDER_SIGNAL; // .SET
if ( values_PREV!= MAIN_UNDER_SIGNAL ){ // ? WAS A FLIP
values_PREV = MAIN_UNDER_SIGNAL; // .SET
ExtMapBuffer3[i+1] = ExtMapBuffer1[i+1]; // .STO[i+1]
ExtMapBuffer3[i ] = ExtMapBuffer2[i ]; // .STO[i+0]
}
}
建议在 New-MQL4 代码的上下文中进行更改：
// ------------------------------------------------------------------------------------
// FOR AN EA-INTEGRATION INTERFACE, ref. below
// ------------------------------------------------------------------------------------
#property strict // check this against OnCalculate() syntax requirement
#property indicator_separate_window
//roperty indicator_level1 75.0 // N/A for aPriceDOMAIN line
//roperty indicator_level2 25.0 // N/A for aPriceDOMAIN line
//roperty indicator_levelcolor clrLimeGreen
//roperty indicator_levelwidth 1
//roperty indicator_levelstyle 0
//roperty indicator_buffers 5 // not used
#property indicator_buffers 3
#property indicator_color1 clrGreen
#property indicator_color2 clrRed
#property indicator_color3 clrDimGray
/*roperty indicator_color4 Green // not used
#property indicator_color5 Red // not used
*/
#property description "Scalping in M5 Custom Indicator......................"
#property description "How to use it ......................................."
#property description "How to setup ........................................"
extern string howtouse = "scalping in M5"; // "New"-MQL4 shows comments in dialog box
extern string contact = "reiz_gamer@yahoo.co.id"; // Contact Email
extern string created = "created by reza rahmad"; // copyright notice
extern int barsToProcess = 100; // Bars To Process ( Depth )
double ExtMapBuffer1[],
ExtMapBuffer2[],
ExtMapBuffer3[];
double buy[];
double sell[];
int values,
values_PREV = EMPTY; // <STATE-FULL>-logic
#define MAIN_ABOVE_SIGNAL 1
#define MAIN_UNDER_SIGNAL 2
//+------------------------------------------------------------------+
//| Custom indicator initialization function |
//+------------------------------------------------------------------+
int OnInit() {
IndicatorShortName( "SigREZ( " + DoubleToStr( barsToProcess, 0 ) + " )");
IndicatorDigits( Digits + 1 ); // override default decimal points
// to be distinguishable once AVG(Close1,Close0) values are calculated
SetIndexStyle( 0, DRAW_LINE ); // MAIN_ABOVE_SIGNAL
SetIndexBuffer( 0, ExtMapBuffer1 ); // segments for values == 1
SetIndexDrawBegin( 0, barsToProcess );
SetIndexStyle( 1, DRAW_LINE ); // MAIN_UNDER_SIGNAL
SetIndexBuffer( 1, ExtMapBuffer2 ); // segments for values == 2
SetIndexDrawBegin( 1, barsToProcess );
SetIndexStyle( 2, DRAW_LINE ); // EMPTY_SEGMENTs
SetIndexBuffer( 2, ExtMapBuffer3 );
SetIndexDrawBegin( 2, barsToProcess );
/*
SetIndexStyle( 3, DRAW_NONE ); // not used
SetIndexBuffer( 3, buy );
SetIndexEmptyValue( 3, 0.0 );
SetIndexStyle( 4, DRAW_ARROW, EMPTY, 3, Magenta );
SetIndexArrow( 4, 234 );
SetIndexBuffer( 4, sell );
SetIndexEmptyValue( 4, 0.0 );
*/
// ----------------------------------------------------------------------------------
// initialization of the generator of random numbers
// ----------------------------------------------------------------------------------
ObjectCreate( "sig", OBJ_TEXT, 0, 0, 0, 0, 0 );
ObjectSetText( "sig", "TAHAN", 10, "Times New Roman", Magenta );
ObjectCreate( "sig1", OBJ_LABEL, 0, 0, 0, 0, 0 );
ObjectSet( "sig1", OBJPROP_XDISTANCE, 750 );
ObjectSet( "sig1", OBJPROP_YDISTANCE, 20 );
ObjectSetText( "sig1", "created by reza rahmad scalping use in tf 5m", 10, "Times New Roman", Magenta );
return(0);
}
//+------------------------------------------------------------------+
//| Custom indicator iteration function |
//+------------------------------------------------------------------+
int deinit() {
ObjectDelete( "tare" );
ObjectDelete( "tarmid" );
ObjectDelete( "tare1" );
ObjectDelete( "sig" );
ObjectDelete( "sig1" );
return(0);
}
//+------------------------------------------------------------------+
//| |
//+------------------------------------------------------------------+
int start() {
int limit = Bars,
counted_bars = IndicatorCounted();
if ( counted_bars > 0 ) counted_bars--;
limit -= counted_bars;
if ( limit > barsToProcess ) limit = barsToProcess;
for ( int i = 0; i < limit; i++ ) {
double main5 = iStochastic( NULL, PERIOD_M5, 14, 3, 3, MODE_SMMA, 0, MODE_MAIN, i );
double signal5 = iStochastic( NULL, PERIOD_M5, 14, 3, 3, MODE_SMMA, 0, MODE_SIGNAL, i );
double ma20 = iMA( NULL, PERIOD_M5, 20, 0, MODE_SMA, PRICE_CLOSE, 0 );
double ma5 = iMA( NULL, PERIOD_M5, 5, 0, MODE_SMA, PRICE_CLOSE, 0 );
if ( main5 > signal5
&& High[0] > ma5
){
ExtMapBuffer1[i] = ( ( Close[i+1] + Close[i] ) / 2 ); // .CALC/.STO
values = MAIN_ABOVE_SIGNAL; // .SET
if ( values_PREV!= MAIN_ABOVE_SIGNAL ){ // ? WAS A FLIP
values_PREV = MAIN_ABOVE_SIGNAL; // .SET
ExtMapBuffer3[i+1] = ExtMapBuffer2[i+1]; // .STO[i+1]
ExtMapBuffer3[i ] = ExtMapBuffer1[i ]; // .STO[i+0]
}
}
if ( main5 < signal5
&& Low[0] < ma5
){
ExtMapBuffer2[i] = ( ( Close[i+1] + Close[i] ) / 2 ); // .CALC/.STO
values = MAIN_UNDER_SIGNAL; // .SET
if ( values_PREV!= MAIN_UNDER_SIGNAL ){ // ? WAS A FLIP
values_PREV = MAIN_UNDER_SIGNAL; // .SET
ExtMapBuffer3[i+1] = ExtMapBuffer1[i+1]; // .STO[i+1]
ExtMapBuffer3[i ] = ExtMapBuffer2[i ]; // .STO[i+0]
}
}
}
}
更安全的 MQL4 集成工具 EA 和自定义指标之间的接口
由于iCustom()语法的性质和参数的顺序，在自定义指标设计阶段创建复制/粘贴界面模板作为 EA 的标题部分要安全得多，这将准备所有相关细节对于安全调用 API合约（无论它在技术上有多弱）
这个模板工具避免了调试语法上可行的无数麻烦和生产力损失，但是由于传递了错误的、混合不当的参数（缺少一个/一个错误的值/一个错误的顺序/）而导致的 iCustom() 错误调用。 ..)
// ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
// COPY/PASTE.START
// ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
// CALL-er SIDE INTERFACE |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
//
// #define sIndicatorPathNAME "#AliceInTheWonderlands_msMOD_0.00"
//
// //_____________________________________INPUT(s)
// // NONE // n/a
//
// //_____________________________________OUTPUT(s):
// #define iOutputDoubleOpenBUFFER 0
// #define iOutputDoubleHighBUFFER 1
// #define iOutputDoubleLowBUFFER 2
// #define iOutputDoubleCloseBUFFER 3
// #define iOutputDoubleVolumeBUFFER 4
// #define iOutputDoubleTimeBUFFER 5
//
// double iCustom( _Symbol, // string symbol, // symbol: Symbol name on the data of which the indicator will be calculated. NULL means the current symbol.
// PERIOD_CURRENT, // int timeframe, // timeframe
// sIndicatorPathNAME, // string name, // path/name of the custom indicator compiled program: Custom indicator compiled program name, relative to the root indicators directory (MQL4/Indicators/). If the indicator is located in subdirectory, for example, in MQL4/Indicators/Examples, its name must be specified as "Examples\\indicator_name" (double backslash "\\"must be specified as separator instead of a single one).
// <<N/A>>, // ...[1] ..., // custom indicator [1]-st input parameters (if necessary)
// // ...[2+] // custom indicator further input parameters (if necessary)
// <iOutputDouble*BUFFER>, // int mode, // line index: Line index. Can be from 0 to 7 and must correspond with the index, specified in call of the SetIndexBuffer() function.
// i // int bar_shift // shift
// );
// ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
// COPY/PASTE.END
// ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
其余的差距来自代码设计。使用三重缓冲线路结构的演示方法完全涵盖了所提出的问题。
剩下的问题与业务逻辑算法化有关，它由 O/P 以独立的、串行序列的 - 构造函数的形式编码，if(){...}根本无法正确处理所有现有的三态 FSA 转换。
