mql4/mql5 error handling | Forex Factory

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mql4/mql5 error handling

  • #1
  • First Post: Apr 5, 2014 6:08pm Apr 5, 2014 6:08pm
Hey I am starting to work myself into the new object oriented mql programming language. I am creating an indicator in which 1 wrong calculation can screw up the entire logic. I do a check if everything is correct but if that is not the case is there a way to throw a custom runtime error and shut down the indicator by itself with a message or loginfo? I could divide by 0 to terminate the indicator but doesn't seem the right way of doing it.
  • #2
  • Apr 6, 2014 3:08am Apr 6, 2014 3:08am
Take a look at the ChartIndicatorDelete() function
  • #3
  • Apr 6, 2014 7:43am Apr 6, 2014 7:43am
The exception handling is missing.
ChartIndicatorDelete() seems like a good candidate for a final executor, but still there should be logic, that controls if the indicator could recover from exception.

ChartIndicatorDelete() is still not bulletproof - since about 610 the MQL4 accepts multiple indicators with equal names in a single subwindow, the ChartIndicatorDelete() may fail to address the defective indicator.
  • #4
  • Apr 6, 2014 12:51pm Apr 6, 2014 12:51pm
Quoting Halley
The exception handling is missing. ChartIndicatorDelete() seems like a good candidate for a final executor, but still there should be logic, that controls if the indicator could recover from exception. ChartIndicatorDelete() is still not bulletproof - since about 610 the MQL4 accepts multiple indicators with equal names in a single subwindow, the ChartIndicatorDelete() may fail to address the defective indicator.
Are you sure that you know what you are talking about?
There is no such thing like exception handling in MQL4/5 like try+catch
And if there are multiple instances of the same indicator on a chart, ChartIndicatorDelete() will serve them as FIFO
If you are using multiple instances you have to take care of them yourself
  • #5
  • Apr 6, 2014 1:03pm Apr 6, 2014 1:03pm
Quoting iwjw
{quote} Are you sure that you know what you are talking about? There is no such thing like exception handling in MQL4/5 like try+catch And if there are multiple instances of the same indicator on a chart, ChartIndicatorDelete() will serve them as FIFO If you are using multiple instances you have to take care of them yourself
What question are you asking? If I am sure that There is not = is missing? Yes, it used to be like that. But no problem, you have the right to think the other way round.
Not sure how FIFO helps you to find the indicator that you want to kill. Could you explain, how you take the care of them yourself?
  • #6
  • Apr 6, 2014 1:17pm Apr 6, 2014 1:17pm
Quoting Halley
{quote} What question are you asking? If I am sure that There is not = is missing? Yes, it used to be like that. But no problem, you have the right to think the other way round. Not sure how FIFO helps you to find the indicator that you want to kill. Could you explain, how you take the care of them yourself?
You can't expect more than MQL is offering
And if there's something missing you would like to have, you have to work around it
You could append an instance# to the shortname of the indicator when launching it (could even be done automatically with a loop using ChartIndicatorName())
myshortname=shortname+instance#
ChartIndicatorDelete(chart_id,sub_window,(unique)shortname)
  • #7
  • Apr 6, 2014 1:30pm Apr 6, 2014 1:30pm
Quoting iwjw
{quote} You can't expect more than MQL is offering And if there's something missing you would like to have, you have to work around it You could append an instance# to the shortname of the indicator when launching it (could even be done automatically with a loop using ChartIndicatorName()) myshortname=shortname+instance# ChartIndicatorDelete(chart_id,sub_window,(unique)shortname)
Sure, the correct answer is "change the short name", does not matter when. But it is not the problem. The problem that OP has, is that there is no framework how to propagate the error to a higher program level to take care of it there rather than at low level function.
  • #8
  • Apr 6, 2014 1:34pm Apr 6, 2014 1:34pm
Then don't use MT4/MQL
Simple as that
  • #9
  • Apr 6, 2014 1:41pm Apr 6, 2014 1:41pm
Quoting iwjw
Then don't use MT4/MQL Simple as that
Interesting argument.
  • #10
  • Last Post: Apr 6, 2014 2:06pm Apr 6, 2014 2:06pm
We are not looking for a framework
We are looking for a solution to terminate an indicator without crashing it by a zero devide
And to propagate it wit a message or a loginfo
That can be done

Rereading our communication there might be some kind of misunderstanding/misinterpreting
"The exception handling is missing" could be seen as a flaw in MQL in general, or as I assumed was applied to my suggestion of using ChartIndicatorDelete()
So sorry if I let out the smartass...
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