95 lines
3.4 KiB
MQL5
95 lines
3.4 KiB
MQL5
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//+------------------------------------------------------------------+
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//| FileHolder.mq5 |
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//| Copyright 2021, MetaQuotes Ltd. |
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//| https://www.mql5.com |
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//+------------------------------------------------------------------+
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#define FILE_DEBUG_PRINT
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#include "..\..\Include\MqlError.mqh"
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#include "..\..\Include\FileHolder.mqh"
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#include "..\..\Include\PRTF.mqh"
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// NB: we will open the same file many times in this script
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// just for demonstration purpose;
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// normally you need only one handle for a file in a program
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const string dummy = "MQL5Book/dummy";
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//+------------------------------------------------------------------+
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//| Subfunction where more file handles are opened in local context |
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//+------------------------------------------------------------------+
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void SubFunc()
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{
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Print(__FUNCTION__, " enter");
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FileHolder holder;
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int h = PRTF(holder.FileOpen(dummy, FILE_BIN | FILE_WRITE | FILE_SHARE_WRITE | FILE_SHARE_READ));
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int f = PRTF(holder.FileOpen(dummy, FILE_BIN | FILE_WRITE | FILE_SHARE_WRITE | FILE_SHARE_READ));
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// use h and f somehow,
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// ...
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// Print(FileHolder::GetFilename(f));
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// no need to close files manually and track early returns
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Print(__FUNCTION__, " exit");
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}
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//+------------------------------------------------------------------+
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//| Script program start function |
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//+------------------------------------------------------------------+
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void OnStart()
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{
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Print(__FUNCTION__, " enter");
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FileHolder holder;
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int h = PRTF(holder.FileOpen(dummy, FILE_BIN | FILE_WRITE | FILE_SHARE_WRITE | FILE_SHARE_READ));
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// some data writing and other action on 'h' could be here
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// ...
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/*
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int a[] = {1, 2, 3};
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FileWriteArray(h, a);
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*/
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SubFunc();
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SubFunc();
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if(rand() > 32000) // imitate branches on possible conditions
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{
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// we do not need this with the holder
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// FileClose(h);
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Print(__FUNCTION__, " return");
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return; // we can have multiple exits from a function
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}
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/*
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... more code
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*/
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// we do not need this with the holder
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// FileClose(h);
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Print(__FUNCTION__, " exit");
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// Note: we do not close any file handles manually
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// FileHolder instances will do it automatically in appropriate destructors
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/*
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output:
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OnStart enter
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holder.FileOpen(dummy,FILE_BIN|FILE_WRITE|FILE_SHARE_WRITE|FILE_SHARE_READ)=1 / ok
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SubFunc enter
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holder.FileOpen(dummy,FILE_BIN|FILE_WRITE|FILE_SHARE_WRITE|FILE_SHARE_READ)=2 / ok
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holder.FileOpen(dummy,FILE_BIN|FILE_WRITE|FILE_SHARE_WRITE|FILE_SHARE_READ)=3 / ok
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SubFunc exit
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FileOpener::~FileOpener: Automatic close for handle: 3
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FileOpener::~FileOpener: Automatic close for handle: 2
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SubFunc enter
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holder.FileOpen(dummy,FILE_BIN|FILE_WRITE|FILE_SHARE_WRITE|FILE_SHARE_READ)=2 / ok
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holder.FileOpen(dummy,FILE_BIN|FILE_WRITE|FILE_SHARE_WRITE|FILE_SHARE_READ)=3 / ok
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SubFunc exit
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FileOpener::~FileOpener: Automatic close for handle: 3
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FileOpener::~FileOpener: Automatic close for handle: 2
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OnStart exit
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FileOpener::~FileOpener: Automatic close for handle: 1
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*/
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}
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//+------------------------------------------------------------------+
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