Author Topic: newbie question: COND limits?  (Read 4308 times)

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MP

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Re: newbie question: COND limits?
« Reply #45 on: November 14, 2010, 09:50:52 AM »
I would add that it's an art, and many programmers don't get it right, and what's "right" is a matter of opinion / taste. My basic stance is that low level routines should rarely, if ever, trap argument type errors, e.g., if a function expects a string and you pass it a real it should do a face plant and cause the calling function to chuck a wobbly, because that's a programming error. I see many programmers applying overly defensive strategies like this, and I think that's a mistake. However, higher level functions / procedures should trap potential errors, e.g. a function that processes csv data should anticipate that one or more fields are null or a data type not expected, because that's a potential execution error.

I acknowledge it can be a matter of taste, this was mine.

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CAB

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Re: newbie question: COND limits?
« Reply #46 on: November 14, 2010, 01:23:01 PM »
Most defensive programing for me is dealing with what the user might or might not do.
Back when I was doing some work in FoxBase & i thought I had all the options covered
I would let a friend of mine put the program through it's paces.
He could break anything & often did. :evil:
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John Kaul (Se7en)

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Re: newbie question: COND limits?
« Reply #47 on: November 14, 2010, 01:34:39 PM »
`Defensive Programing'? I read that book when it was called "Forethought". The continuation of this discussion aught to be very interesting to say the lest.
“Common sense is not so common.” ~Voltaire

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CHulse

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Re: newbie question: COND limits?
« Reply #48 on: November 15, 2010, 05:12:38 AM »
...e.g. a function that processes csv data should anticipate that one or more fields are null or a data type not expected, because that's a potential execution error....

Ok, now you really have my attention. (it's 5 am here and I have coffee  :-D)
Any guidence on how I might address a null field? So far, I have just been very careful formatting the input data...
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Kerry

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Re: newbie question: COND limits?
« Reply #49 on: November 15, 2010, 05:48:11 AM »

If unexpected null data, tell the user nicely, then spit the dummy.

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CAB

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Re: newbie question: COND limits?
« Reply #50 on: November 15, 2010, 08:51:25 AM »
A more ambitious option would be to get input form the user for that data.
Use it this time and or update the data file. You would need to know if this user had permission to update the file.
One more option would be to check the file while loading for incorrect data & deal with it at that time.
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