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MetaQuotes Software Corp.
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178203
MetaQuotes Software Corp. 2014.02.06 14:31 

mt4R for new MQL4:

mt4R, modified for supporting new MQL4

Author: micclly

Alberto Jorge Cushnir
233
Alberto Jorge Cushnir 2014.02.06 19:30  

Thanks for your contribution.

It's nice to know somebody takes care about useful projects.

best regards

MQL4 Comments
16319
MQL4 Comments 2014.02.07 04:53  
acushnir:

Thanks for your contribution.

It's nice to know somebody takes care about useful projects.

best regards


Can you specify what changes were necessary to update the dll? I wasn't aware that dlls need to be changed to fit MQL5's format. Have you any links on this subject?
micclly
185
micclly 2014.02.07 06:07  
FXEZ:
Can you specify what changes were necessary to update the dll? I wasn't aware that dlls need to be changed to fit MQL5's format. Have you any links on this subject?

string in new MQL4 is not an array of char but an array of wchar_t.

If your old indicator/script/EA which worked on MT4 build509 or earlier uses string and passes it to DLL functions, you MUST change the function to wchar_t version.

For example, if it uses ShellExecuteA, change it to ShellExecuteW.

Unfortunately if the dll you use does not provide wchar_t version functions like mt4R.dll, you must modify DLL implementation, or convert an string to an array of char by WideCharToMultiByte Win32API.

Note: I haven't tried WideCharToMultiByte yet on new MQL4, so I don't know you can use WideCharToMultiByte without or with any problem.

At the build 600 release topic, it is said as follows:

Changes in MQL4 Language

  • Strings are now presented in Unicode format, though they were in ANSI format (single byte ones) before. That should be considered if the program uses DLLs and passes string variables to them. When calling Windows API functions, Unicode versions of these functions should be used.
MQL4 Comments
16319
MQL4 Comments 2014.02.07 07:57  
Thanks for the explanation, and the update!
MQL4 Comments
16319
MQL4 Comments 2014.02.08 15:28  

Fist of all: Thank you so much for porting it to the new version! Excellent job!

However, I've encountered a problem. See this simple script:

//+------------------------------------------------------------------+
//|                                                  TestNewMt4R.mq4 |
//|                                                                  |
//|                                                                  |
//+------------------------------------------------------------------+
#property copyright ""
#property link      ""
#property version   "1.00"
#property strict
#include <mt4R.mqh>
#define RPATH "D:/Program Files/R/R-3.0.2/bin/i386/Rterm.exe --no-save"
#define RDEBUG 2
string times[1000];
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
  {
   StartR(RPATH,RDEBUG);
   for(int i=0; i<1000; i++)
     {
      times[i]=TimeToString(iTime(Symbol(),Period(),i),TIME_DATE|TIME_SECONDS);
     }
   Rf("times",times);
   Rx("gc()");
   StopR();  
  }
//+------------------------------------------------------------------+

It crashes when trying to execute

Rf("times",times);

And I don't know why. I think the problem might be the one you mentioned regarding strings. However, I cannot resolve it by myself so help is very much appreciated.

Thanks!

EDIT:

I checked DebugView and it seems that the whole String handling is somehow broken, e.g.,

void OnStart()
  {
   StartR(RPATH,RDEBUG);
   string testString = "This is a string copy test.";
   
   Rs("rString", testString);
   
   Rx("gc()");
   StopR();
  }

Results in:

Wrong copy of string

MQL4 Comments
16319
MQL4 Comments 2014.02.08 18:51  

Thanks for fixing it! Works great! One more minor change is required though:

// assign string to variable given by name
procedure RAssignString(AHandle: LongInt; AVariable: PWideChar; AValue: PChar (should also be PWideChar?)); stdcall;
begin
  if isValid(AHandle) then
    TRConsole(AHandle).AssignString(WideStringToString(AVariable, CP_ACP), WideStringToString(AValue, CP_ACP));
end;
micclly
185
micclly 2014.02.08 18:54  
TJmclovin:
It crashes when trying to execute
Rf("times",times);


Thanks for your bug report!

From the investigation, the array processing in RAssingStringVector is not correctly ported to new MQL4.

I've updated the DLL, so please get the latest version from GitHub.

In this version, DLL-hardcoded minor version number updated to 4, so please also copy MQL4/Include/mt4R.mqh.

micclly
185
micclly 2014.02.08 19:09  
TJmclovin:

Thanks for fixing it! Works great! One more minor change is required though:

// assign string to variable given by name
procedure RAssignString(AHandle: LongInt; AVariable: PWideChar; AValue: PChar (should also be PWideChar?)); stdcall;
begin
  if isValid(AHandle) then
    TRConsole(AHandle).AssignString(WideStringToString(AVariable, CP_ACP), WideStringToString(AValue, CP_ACP));
end;


Thanks for bug report, I've fixed at v1.4.0-SNAPSHOT-b5.

Please update the dll and the include file, because of minor version number is changed from before b3.

MQL4 Comments
16319
MQL4 Comments 2014.02.08 19:46  

Excellent job! Thanks for the instant fixes :) !!!

Two more things:

  • RGetInteger: AExpression: PChar should be PWideChar and subsequently Result := TRConsole(AHandle).GetInteger(WideStringToString(AExpression, CP_ACP))
  • RGetBool: Same as above :)

Again, thank your very much !

EDIT: Next time I'll just open an issue at your repo if you don't mind. I don't want to spam the comments section here ;)

micclly
185
micclly 2014.02.08 20:08  
TJmclovin:

Excellent job! Thanks for the instant fixes :) !!!

Two more things:

  • RGetInteger: AExpression: PChar should be PWideChar and subsequently Result := TRConsole(AHandle).GetInteger(WideStringToString(AExpression, CP_ACP))
  • RGetBool: Same as above :)

Again, thank your very much !


Great thank you and I'm sorry about terrible porting quality...

I've fixed RGetBoo/RGetInteger bug at v1.4.0-SNAPSHOT-b6.


EDIT: Next time I'll just open an issue at your repo if you don't mind. I don't want to spam the comments section here ;) 


I'll welcome for iissue from you if you feel to report something about this!

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