Discussion of article "The Use of the MQL5 Standard Trade Class libraries in writing an Expert Advisor" - page 2

[[Deleted]]

Trolls:

What am I doing wrong ? Why is the Bid not printed ?

Here is the log of work

2011.01.31 20:20:18 00 (EURUSD,M1) EURUSD 0

here is the code

Use \my_symbol.RefreshRates();\ instead of \my_symbol.Refresh();\. Then it works!

[Trolls]

-Alexey-:
Use \my_symbol.RefreshRates();\ instead of \my_symbol.Refresh();\. Then it works!

Thanks.

This is probably a question for the developers or the person who writes the Help.

The article says

mysymbol.Refresh()
Used to refresh all data for a symbol. When you specify a new symbol name for a class, it is called automatically.

mysymbol.RefreshRates()
Used to update quotes. When a new symbol is set, it is called automatically.

1. It turns out that not all data ?

2. What is the difference between specifying a new symbol and setting a new symbol ?

3. I don't understand the word automatically. I seem to have set a symbol with the command my_symbol.Name(_Symbol), but the update did not happen....

[Yedelkin]

Trolls:

The article said

mysymbol.Refresh()
Used to refresh all data for a symbol. When a new symbol name is specified for a class, it is called automatically.

mysymbol.RefreshRates()
Used to refresh quotes. When a new symbol is set, it is called automatically.

1. It turns out that not all data ?

2. What is the difference between specifying a new character and setting a new character ?

3. I don't understand the word automatically. I seem to have set a symbol with the command my_symbol.Name(_Symbol), but the update didn't happen....

That rare moment when you don't have to wait for an answer from the author of the article or the author of the reference book :) It's enough to look at the source code to see that RefreshRates() completely duplicates the SymbolInfoTick() function , which "returns current prices for the specified symbol in a variable of MqlTick type". Therefore, when the authors say "about updating quotes", they are actually talking about updating values of a variable of MqlTick type.

2. There is such a line in the source code

void  Name(string name)  { m_name=name; Refresh();}

This indicates that when calling the Name() function, only the Refresh() function is automatically activated. I have not found any information about the automatic activation of the RefreshRates() function when calling the Name() function. Therefore, it turns out that "as of today" a change of a symbol for the Name() function does not automatically activate the RefreshRates() function. We will have to update the values of the variable of MqlTick type ("refresh quotes") independently and forcibly.

[Yedelkin]

Trolls:

What am I doing wrong? Why Bid is not printed? Here is the work log 2011.01.31 20:20:18 00 (EURUSD,M1) EURUSD 0

here is the code

void OnTick()
  {
   my_symbol.Name(_Symbol);
   my_symbol.Refresh();
   Print(_Symbol," ",my_symbol.Bid());
  }

Here is the answer why the Bid value is printed as zero. The source code shows that the Bid() function is described by the line

double  Bid()  const { return(m_tick.bid);}

Thus, the value of the Bid() function is bound to the value of one of the elements of a variable of the MqlTick type. And this variable is updated not automatically when a symbol is changed, but by an additional call of the RefreshRates() function. In your code, the Refresh() function is called - in fact, it is called twice (taking into account the body of the Name() function) - and the RefreshRates() function is not called once.

[[Deleted]]

Probably you can improve the code by adding a call to Refresh() in the final part ofRefresh(). then all the data will really be updated.....

[Yedelkin]

Interesting:
Perhaps you can improve the code by adding theRefreshRates () call in the final part ofRefresh(). then all the data will really be updated.....

I added the RefreshRates() call to the Name() function. But still - these are patches at the level of an individual user for his needs.

[[Deleted]]

Yedelkin:
I added the RefreshRates() call to the Name() function. But still - these are patches at the level of an individual user for his needs.

But if the developers put Refresh() in other places (at their discretion) it will be a normal solution for most users.

If we say that Refresh updates all data, then all data should really be updated. IMHO

[Yedelkin]

Interesting:

But if the developers put it in Refresh() and in other places (at their discretion) it will be a normal solution for most users.

If we say that Refresh updates all data, then all data should really be updated. IMHO

There is no argument with that. But still, a normal solution for users would be a clear and understandable description of available designs and their properties. Then the user himself will figure out how to use these constructs. And since such a solution is hard to achieve due to various reasons, those who ask additional questions to themselves and others will move forward :)

[[Deleted]]

Yedelkin:
There is no argument with that. But still, the normal solution for users would be a clear and understandable description of available designs and their properties. Then the user himself will figure out how to use these constructions. And since such a solution is hard to achieve due to various reasons, those who ask additional questions to themselves and others will move forward :)

I don't know, I use the standard library only for study purposes. I write all my projects on my own components.

I'll wait until constructors will be made more convenient, then I'll give up the standard library altogether....

[Yedelkin]

By the way, I found out that the CHistoryOrderInfo class has a couple of lines like this one

return(FormatType(str,Type()));
...
FormatType(type,Type())

But the Type() function is absent in the class.