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 exception handling in skill/ocean 

Last post Mon, Nov 12 2012 7:27 PM by mbchang. 10 replies.
Started by swdesigner 13 Aug 2012 10:51 AM. Topic has 10 replies and 2690 views
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  • Mon, Aug 13 2012 10:51 AM

    exception handling in skill/ocean Reply
    I searched the community and support.cadence, but couldn't find any reference material or source code examples showing how to handle exceptions in skill/ocean.

    For example, my ocean script loops voltage using foreach to do several runs. After each run, I do some postprocessing. If some of the post-processing fails because a condition being looked for in the simulation is not found, I want the rest of the runs to complete. Instead what happens is the ocean script exits with an error.

    For example, if I am looking for  a rising edge on a certain signal and it doesn’t exist..

    Any help will be great.

     
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    • Post Points: 20
  • Mon, Aug 13 2012 12:11 PM

    • marcelpreda
    • Top 150 Contributor
    • Joined on Tue, Jan 19 2010
    • Bucharest, Romania
    • Posts 44
    • Points 715
    Re: exception handling in skill/ocean Reply

     Hi there,

     

    Have a look at

    errset(skill_expr [bool])

    It tries to execute skill_expr,

    if it is ok the result is return as list

    if skill_expr rise an error then returns nil, if bool == t the error message is also printed.

    E.g.

    errset(x = list(1 2 3))
    ((1 2 3))
    errset(x = listx(1 2 3))
    nil
    errset(x = listx(1 2 3) t)
    *Error* eval: undefined function - listx
    nil

     

    BR,

    Marcel

    • Post Points: 20
  • Mon, Aug 13 2012 1:28 PM

    Re: exception handling in skill/ocean Reply
    Thank you! I will try that.
    • Post Points: 20
  • Tue, Aug 14 2012 2:48 AM

    Re: exception handling in skill/ocean Reply

     The other approach I would recommend is actually checking the return values of various functions in your code. For example, v("/out" ?result 'tran) will return nil if that signal is not there. Similarly other functions may return nil (such as riseTime) if there is no rising edge - so conditional checks in your code will allow you to detect when things are not correct.

    errset() is the alternative as Marcel suggested, but often more defensive programming will allow you to cope with differences in the data more eloquently than just trapping errors.

    Regards,

    Andrew.

    • Post Points: 35
  • Tue, Aug 14 2012 3:24 AM

    • marcelpreda
    • Top 150 Contributor
    • Joined on Tue, Jan 19 2010
    • Bucharest, Romania
    • Posts 44
    • Points 715
    Re: exception handling in skill/ocean Reply

     Hi *,

    of course Andrew is right.

    Better to use if/else to "validate" data.


    I use errset when generate and execute skill code on the fly, sometimes I generate syntax errors or call missing/unexisting functions and that's the only way to catch them.

    Best Regards,

    Marcel

    • Post Points: 5
  • Tue, Aug 14 2012 10:55 AM

    Re: exception handling in skill/ocean Reply

    The logic is unassailable. But what can we do to make the programming easier. At our location we've had people take full-fledged ocean-scripting classes and still, no one uses it. It's extremely unfriendly. How can we go from "linux" to "ipad"?

    Putting in all this error-checking will only make the code even more intimidating..

    BTW, did you mean "elegantly" or "eloquently"? :)

    • Post Points: 20
  • Tue, Aug 14 2012 1:28 PM

    Re: exception handling in skill/ocean Reply

    If you want iPad, use ADE XL - which captures much of this in a UI. Programming languages are by nature flexble - and with flexibility comes (unfortunately) the need to cope with unexpected situations - it's very hard for a general programming language to do the right thing if it has no idea what the right thing should be given that your code could do anything...

    And yes I did mean eloquently (well written (yes, strictly it's well spoken, but I thought I'd be free to adapt my own language!)), but "elegantly" fits too.

    It really shouldn't be intimidating. Usually the conditions don't have to be complicated. I normally advise people to use things like:

    unless(member('tran results())
      ...
    )

    to check if the transient results are present - little idioms like this are easy enough to remember, even for non-programmers (and most engineers should have at least some programming knowledge these days).

    Glad they take the OCEAN class (I wrote it!). Surprised it's not used that much though - I tend to find many users who do because of the flexibility it gives them.

    Regards,

    Andrew.

    • Post Points: 20
  • Thu, Nov 8 2012 2:19 PM

    • mbchang
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    • Joined on Thu, Sep 6 2012
    • Posts 9
    • Points 150
    Re: exception handling in skill/ocean Reply

    Andrew,

     

    If there are some errors when execute the OCEAN scripts,  how can I exit the OCEAN (or OCEAN environment)? I found the ocean is always hangng if there are errors. I am looking for some error handling solutions like other languages in OCEAN.

     

    Thanks,

    Jerry 

    • Post Points: 20
  • Thu, Nov 8 2012 3:21 PM

    • skillUser
    • Top 10 Contributor
    • Joined on Fri, Sep 19 2008
    • Austin, TX
    • Posts 2,567
    • Points 15,575
    Re: exception handling in skill/ocean Reply

    Hi Jerry,

    You can use "errset" to wrap or programmatically trap errors, as noted briefly in Solution 11508500 or Solution 11030618.

    Hopefully this answers your question?

    Regards,

    Lawrence.

    • Post Points: 20
  • Thu, Nov 8 2012 11:06 PM

    Re: exception handling in skill/ocean Reply

    Jerry,

    The various strategies (using conditional statements to detect presence of results, using errset) have been covered earlier in this thread. I wouldn't expect that errors would cause anything to hang though - so presumably the problem you're seeing is down to something else.

    Maybe contacting customer support with the details of your problem would be wise?

    Regards,

    Andrew.

    • Post Points: 20
  • Mon, Nov 12 2012 7:27 PM

    • mbchang
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    • Joined on Thu, Sep 6 2012
    • Posts 9
    • Points 150
    Re: exception handling in skill/ocean Reply

    Lawrence and Andrew,

     

    errset does resolve my issue.

     

    Thank you very much for your help!

     

    Regards,

    Jerry

    • Post Points: 5
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Started by swdesigner at 13 Aug 2012 10:51 AM. Topic has 10 replies.