Discussion of article "LifeHack for traders: Blending ForEach with defines (#define)"
Forum on trading, automated trading systems and testing trading strategies
Libraries: CDouble & CDoubleVector
amrali, 2018.02.12 23:53
#define forEach(element, array) for (int __i = 0, __max = ArraySize((array)); __i < __max && ((element) = array[__i]) == (element); __i++)
Forum on trading, automated trading systems and testing trading strategies
Renat Fatkhullin, 2015.02.10 08:16
I haven't run the code yet, but the source code shows the classic error of wrong end date in HistorySelect.
Every first programmer calls this function with wrong date, constantly snacks the end of history and detects "long time trade getting into history".
Forum on trading, automated trading systems and testing trading strategies
Renat Fatkhullin, 2015.02.10 09:15
The mistake is that people do not think about what the current moment is and substitute the wrong date taken from the wrong source.
It is enough to specify a known distant date as the end date, not the obsolete serverTime.
Forum on trading, automated trading systems and testing trading strategies
Renat Fatkhullin, 2015.02.10 13:56
And the start and end date should be set with the realisation of errors and with a mandatory margin. That is, minus N sec and plus N sec as a minimum.
TimeTradeServer() is not a rltime accurate time, but is updated solely on price ticks coming into the market overview.
If you suddenly have no data in the history sample, it means 99% that the error is in the query boundaries.
HistorySelect(0, LONG_MAX);
Предопределённые переменные _XXXX переводятся в функции MQL5 при помощи беспараметрической формы #define:
//--- the _Digits variable stores number of digits after a decimal point, #define _Digits Digits()
//--- the latest known seller's price (ask price) for the current symbol double GetAsk() { MqlTick tick; SymbolInfoTick(Symbol(),tick); return(tick.ask); }
Terribly expensive! If you really want to do it through the structure, you should have at least done it. And there is no check for some reason.
SymbolInfoDouble is fully compliant with MT4.
#define IsTradeContextBusy true
Huh?
maybe false?Forum on trading, automated trading systems and testing trading strategies.
fxsaber, 2017.09.26 09:55 pm.
bool RefreshRates( void ) { return(true); } double MarketInfo( const string Symb, const ENUM_SYMBOL_INFO_DOUBLE Property ) { return(SymbolInfoDouble(Symb, Property)); } int MarketInfo( const string Symb, const ENUM_SYMBOL_INFO_INTEGER Property ) { return((int)SymbolInfoInteger(Symb, Property)); } bool IsTesting(void) { return(MQLInfoInteger(MQL_TESTER) || MQLInfoInteger(MQL_OPTIMIZATION)); } bool IsTradeContextBusy( void ) { return(false); } bool IsTradeAllowed(void) { return(MQLInfoInteger(MQL_TRADE_ALLOWED)); } bool IsExpertEnabled(void) { return(AccountInfoInteger(ACCOUNT_TRADE_EXPERT)); } int ObjectFind( const string Name ) { return(ObjectFind(0, Name)); } int ObjectsTotal( void ) { return(ObjectsTotal(0)); } bool ObjectDelete( const string Name ) { return(ObjectDelete(0, Name)); } string ObjectName( const int Pos ) { return(ObjectName(0, Pos)); } double AccountFreeMarginCheck(const string Symb,const int Cmd,const double dVolume) { double Margin; return(OrderCalcMargin((ENUM_ORDER_TYPE)Cmd, Symb, dVolume, SymbolInfoDouble(Symb, (Cmd == ORDER_TYPE_BUY) ? SYMBOL_ASK : SYMBOL_BID), Margin) ? AccountInfoDouble(ACCOUNT_MARGIN_FREE) - Margin : -1); } #define False false #define True true #define Digits _Digits #define Point _Point #define MODE_BID SYMBOL_BID #define MODE_ASK SYMBOL_ASK #define MODE_POINT SYMBOL_POINT #define MODE_DIGITS SYMBOL_DIGITS #define MODE_STOPLEVEL SYMBOL_TRADE_STOPS_LEVEL #define MODE_SPREAD SYMBOL_SPREAD #define StrToTime StringToTime #define StrToInteger StringToInteger #define TimeToStr TimeToString #define DoubleToStr DoubleToString #define Bid SymbolInfoDouble(_Symbol, SYMBOL_BID) #define Ask SymbolInfoDouble(_Symbol, SYMBOL_ASK)
fxsaber:
В копилку
#define forEach(element, array) for (int __i = 0, __max = ArraySize((array)); __i < __max && ((element) = array[__i]) == (element); __i++)
Interesting and non-obvious technique )
How many twisted things can you do?
Define is a stupid substitution of one text for another. There's no power in them!
Better try to do the same thing on templates.
How many times can you do this?
Define is a stupid substitution of one text for another. There's no power in them!
Less writing is sometimes convenient
Better try to do the same thing on templates.
It's just a question of feasibility, usability and performance.
- Free trading apps
- Over 8,000 signals for copying
- Economic news for exploring financial markets
You agree to website policy and terms of use
New article LifeHack for traders: Blending ForEach with defines (#define) has been published:
The article is an intermediate step for those who still writes in MQL4 and has no desire to switch to MQL5. We continue to search for opportunities to write code in MQL4 style. This time, we will look into the macro substitution of the #define preprocessor.
Creating Expert Advisors almost always entails a lot of work with loops. Loops surround us everywhere: searching orders, trades in history, chart objects, Market Watch symbols, bars in an indicator buffer. To make a programmer's life a bit easier, MetaEditor features snippets meaning that when you enter the first characters, they automatically turn into a small piece of code after pressing Tab. This is how the 'for' loop snippet works:
Author: Vladimir Karputov