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Groups > comp.lang.java.programmer > #24677
| From | Robert Klemme <shortcutter@googlemail.com> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: About java program. |
| Date | 2013-07-06 13:14 +0200 |
| Message-ID | <b3qcg6FdmhoU1@mid.individual.net> (permalink) |
| References | (9 earlier) <85GdncWZdo04-lzMnZ2dnUVZ8mydnZ2d@bt.com> <51d6396c$0$295$14726298@news.sunsite.dk> <lvmdnWcxpKm1HUvMnZ2dnUVZ8sadnZ2d@bt.com> <b3orbvF417nU1@mid.individual.net> <qPOdnUfgG8PKT0rMnZ2dnUVZ8uadnZ2d@bt.com> |
On 06.07.2013 10:16, lipska the kat wrote:
> On 05/07/13 22:15, Robert Klemme wrote:
>> On 05.07.2013 10:13, lipska the kat wrote:
>>> On 05/07/13 04:11, Arne Vajhøj wrote:
>>
>>>> The above has nothing to do with defensive coding. It does
>>>> not protect against anything that the simple:
>>>
>>> For goodness sake *read the post*
>>>
>>> I said 'lack of error handling notwithstanding'
>>>
>>> Do you understand what that means?
>>>
>>> Do you want an example of defensive coding?
>>>
>>> READ THIS FIRST
>>> This is an *example* ... got that, good.
>>
>> Funny thing is that people will only see in an example what is presented
>> in the example. So if there is an example which leaves place for
>> specific error handling and that error handling is not included people
>> won't see it. They just see a method with unnecessary complexity.
>>
>> Maybe you'll say it's not easy to pick a good example. But examples are
>> there for a reason: they are used as tools to communicate something. If
>> they fail to do that they should be improved or left out.
>>
>>> and no, I haven't compiled it and no, I wouldn't normally hard code
>>> messages in this way (jeez)
>>>
>>> Now then
>>>
>>> private boolean askYesNoquestion (String str) throws
>>> BadArgumentException{
>>>
>>> boolean result = false;
>>>
>>> if(null == str){
>>> logger.log("Argument is null");
>>> throw new BadArgumentException("Argument is null");
>>> }
>>> else{
>>> if(str.equals("yes")){
>>> result = true;
>>> }
>>> else if(!str.equals("no")){
>>> logger.log("Incorrect Argument, argument is " + str);
>>> throw new BadArgumentException("argument is " + str);
>>> }
>>> }
>>> return result;
>>> }
>>>
>>> This is *one* way of doing it
>>>
>>> Overkill ... no, defensive yes.
>>
>> This example demonstrates what I will call bad practice: the exception
>> is thrown so the calling code can decide how to handle the error.
>> It may actually be that the caller can perfectly deal with that situation
>> and proceed normally. Method askYesNoquestion() cannot know this. But
>> because the method does the logging itself you'll end up seeing messages
>> in a log file for things which are not noteworthy. I say, either log
>> and deal with the error locally OR throw an exception containing a
>> meaningful message - but not both. That is misleading.
>
> Frankly I think you are missing the whole point of defensive programming.
>
> You yourself said
>
> "It may actually be that the caller can perfectly deal with that
> situation..."
>
> The important word here is *may* ... what happens if the caller decides
> to ignore the exception, or maybe handle it without recording the
> reason. What are you left with ...
Well, you can forget the logging on *any* level of the application.
There is no really a difference between asking the author of this method
to do proper error handling or asking the author of some other code to
do it.
> The example is trivial I agree but the concept is sound.
If you do that kind of logging in all sorts of methods you'll end up
with extreme volumes of logfiles that make it hard to detect real bugs
and cost significant IO.
> ... and who says these things are not *noteworthy*. If you are
> programming defensively then *everything* is noteworthy.
For me "defensive programming" in this example means to check arguments
and throw NPE or IllegalArgumentException if the data passed into the
method violates the specified (e.g. in JavaDoc) contract. Nothing more.
Errors will show up. If the caller does not handle exceptions
properly then the exception will show up somewhere up the call stack
where it's logged or presented to the user. Easy to find bugs then.
> IMHO it is bad practice *not* to log the error at the point of origin.
The point is: you do not know whether it _is_ an error inside this
method. You know arguments violate the contract, but you do not know
whether that poses a problem for the program. Hence: throw an exception
and be done.
> There's an old adage in this business "You can never have too much data"
> This is especially true when programing defensively.
I disagree.
Cheers
robert
--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/
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About java program. rajbhaumik@gmail.com - 2013-06-15 13:38 -0700
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-06-15 16:50 -0400
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-06-16 01:12 +0200
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-16 14:21 +0100
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-06-16 17:28 +0200
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-16 19:52 +0100
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-06-16 15:50 -0400
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-17 09:36 +0100
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-17 09:49 -0300
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-17 14:46 +0100
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-17 13:32 -0300
Re: About java program. Joerg Meier <joergmmeier@arcor.de> - 2013-06-17 20:32 +0200
Re: About java program. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-06-17 14:49 -0400
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-17 18:38 -0300
Re: About java program. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-06-17 18:30 -0400
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-18 17:33 -0300
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-07-04 22:56 -0400
Re: About java program. Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-06-18 00:13 +0200
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-18 17:50 -0300
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-19 08:50 +0100
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-19 15:16 -0300
Re: About java program. Lew <lewbloch@gmail.com> - 2013-06-19 16:20 -0700
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-07 13:31 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-07 18:16 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-07 19:21 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-07 20:07 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-07 20:21 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-07 20:40 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-07 22:20 -0400
Re: About java program. Lew <lewbloch@gmail.com> - 2013-07-07 21:47 -0700
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-08 06:58 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-08 08:07 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-08 08:58 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-08 09:18 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-08 09:47 -0400
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-07-08 10:07 -0400
Re: About java program. Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-06-19 16:42 +0200
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-20 23:33 -0300
Re: About java program. Martin Gregorie <martin@address-in-sig.invalid> - 2013-06-21 04:16 +0000
Re: About java program. Joerg Meier <joergmmeier@arcor.de> - 2013-06-21 12:27 +0200
Re: About java program. Martin Gregorie <martin@address-in-sig.invalid> - 2013-06-21 21:14 +0000
Re: About java program. Joerg Meier <joergmmeier@arcor.de> - 2013-06-21 23:37 +0200
Re: About java program. Martin Gregorie <martin@address-in-sig.invalid> - 2013-06-21 23:42 +0000
Re: About java program. Gene Wirchenko <genew@telus.net> - 2013-06-24 13:00 -0700
Re: About java program. Martin Gregorie <martin@address-in-sig.invalid> - 2013-06-24 21:29 +0000
Re: About java program. Martin Gregorie <martin@address-in-sig.invalid> - 2013-06-24 21:42 +0000
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-21 23:59 -0300
Re: About java program. Martin Gregorie <martin@address-in-sig.invalid> - 2013-06-22 13:30 +0000
Re: About java program. Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-06-21 16:24 +0200
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-21 22:39 -0300
Re: About java program. Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-06-22 19:25 +0200
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-22 19:41 +0100
Re: About java program. Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-06-23 03:53 +0200
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-23 09:21 +0100
Re: About java program. Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-06-24 18:57 +0200
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-24 18:14 +0100
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-22 09:03 +0100
Re: About java program. Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2013-06-22 19:26 +0200
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-22 18:51 +0100
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-07-04 22:58 -0400
Re: About java program. Joerg Meier <joergmmeier@arcor.de> - 2013-06-19 00:38 +0200
Re: About java program. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-06-18 18:56 -0400
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-18 21:26 -0300
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-06-19 21:20 +0200
Re: About java program. Sven Köhler <remove-sven.koehler@gmail.com> - 2013-06-20 11:23 +0300
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-06-20 19:18 +0200
Re: About java program. blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2013-07-15 20:20 +0000
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-19 09:14 +0100
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-19 09:11 +0100
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-07-04 23:11 -0400
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-07-05 09:13 +0100
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-07-05 23:15 +0200
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-07-05 22:03 -0400
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-07-06 13:01 +0200
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-07-06 13:43 +0100
Re: About java program. Martin Gregorie <martin@address-in-sig.invalid> - 2013-07-06 14:17 +0000
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-07-06 16:18 -0400
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-07-06 21:42 +0100
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-07-06 09:16 +0100
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-07-06 13:14 +0200
Re: About java program. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-07-06 08:22 -0400
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-07-07 20:43 +0200
Re: About java program. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-07-07 18:07 -0400
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-07-07 19:35 -0400
Re: About java program. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-07-07 20:42 -0400
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-07-08 20:50 +0200
Re: About java program. Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-07-08 15:01 -0400
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-07-08 23:29 +0200
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-07-06 16:27 -0400
Re: About java program. Lew <lewbloch@gmail.com> - 2013-07-06 13:41 -0700
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-07-05 21:59 -0400
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-17 21:06 +0100
Re: About java program. Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2013-06-17 17:36 -0500
Re: About java program. Robert Klemme <shortcutter@googlemail.com> - 2013-06-18 08:24 +0200
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-18 09:03 +0100
Re: About java program. Joshua Cranmer 🐧 <Pidgeot18@verizon.invalid> - 2013-06-18 13:07 -0500
Re: About java program. Lew <lewbloch@gmail.com> - 2013-06-18 14:48 -0700
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-19 08:36 +0100
Re: About java program. Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-06-18 23:33 -0300
Re: About java program. lipska the kat <"nospam at neversurrender dot co dot uk"> - 2013-06-19 08:34 +0100
Re: About java program. Arne Vajhøj <arne@vajhoej.dk> - 2013-07-04 22:53 -0400
Re: About java program. Roedy Green <see_website@mindprod.com.invalid> - 2013-06-16 07:04 -0700
Re: About java program. Jeff Higgins <jeff@invalid.invalid> - 2013-06-18 04:06 -0400
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