Last modified: 2012-02-14 17:43:49 UTC
`[[Corresponds to::0 xxx]]' causes error message: Warning: Division by zero in /var/www/ocw/mediawiki-1.17.1/extensions /SemanticMediaWiki/includes/datavalues/SMW_DV_Quantity.php on line 30 and `Special:Internal error' with stack backtrace: Initialisation value '' is not a number. Backtrace: #0 /var/www/ocw/mediawiki-1.17.1/extensions/SemanticMediaWiki/includes/datavalues/SMW_DV_Quantity.php(30): SMWDINumber->__construct(false, '_qty') #1 /var/www/ocw/mediawiki-1.17.1/extensions/SemanticMediaWiki/includes/datavalues/SMW_DV_Number.php(110): SMWQuantityValue->convertToMainUnit(1, '????????') #2 /var/www/ocw/mediawiki-1.17.1/extensions/SemanticMediaWiki/includes/datavalues/SMW_DataValue.php(169): SMWNumberValue->parseUserValue('1 ????????') #3 /var/www/ocw/mediawiki-1.17.1/extensions/SemanticMediaWiki/includes/SMW_DataValueFactory.php(113): SMWDataValue->setUserValue('1 ????????', false) #4 /var/www/ocw/mediawiki-1.17.1/extensions/SemanticMediaWiki/includes/SMW_DataValueFactory.php(177): SMWDataValueFactory::newTypeIdValue('_qty', '1 ????????', false, Object(SMWDIProperty), Object(SMWDIWikiPage)) #5 /var/www/ocw/mediawiki-1.17.1/extensions/SemanticMediaWiki/includes/SMW_ParseData.php(113): SMWDataValueFactory::newPropertyObjectValue(Object(SMWDIProperty), '1 ????????', false, Object(SMWDIWikiPage)) #6 /var/www/ocw/mediawiki-1.17.1/extensions/SemanticMediaWiki/includes/SMW_ParserExtensions.php(165): SMWParseData::addProperty('Time to search', '1 ????????', false, Object(Parser), true) #7 /var/www/ocw/mediawiki-1.17.1/extensions/SemanticMediaWiki/includes/SMW_ParserExtensions.php(112): SMWParserExtensions::parsePropertiesCallback(Array) #8 [internal function]: SMWParserExtensions::simpleParsePropertiesCallback(Array) #9 /var/www/ocw/mediawiki-1.17.1/extensions/SemanticMediaWiki/includes/SMW_ParserExtensions.php(71): preg_replace_callback('/\[\[ ...', Array, '?* [[Time to se...') #10 [internal function]: SMWParserExtensions::onInternalParseBeforeLinks(Object(Parser), '?* [[Time to se...', Object(StripState)) #11 /var/www/ocw/mediawiki-1.17.1/includes/Hooks.php(158): call_user_func_array(Array, Array) #12 /var/www/ocw/mediawiki-1.17.1/includes/parser/Parser.php(1005): wfRunHooks('InternalParseBe...', Array) #13 /var/www/ocw/mediawiki-1.17.1/includes/parser/Parser.php(283): Parser->internalParse('<!-- * [[Time t...') #14 /var/www/ocw/mediawiki-1.17.1/includes/EditPage.php(1939): Parser->parse('<!-- * [[Time t...', Object(Title), Object(ParserOptions)) #15 /var/www/ocw/mediawiki-1.17.1/includes/EditPage.php(1218): EditPage->getPreviewText() #16 /var/www/ocw/mediawiki-1.17.1/includes/EditPage.php(437): EditPage->showEditForm() #17 /var/www/ocw/mediawiki-1.17.1/includes/EditPage.php(296): EditPage->edit() #18 /var/www/ocw/mediawiki-1.17.1/includes/Wiki.php(522): EditPage->submit() #19 /var/www/ocw/mediawiki-1.17.1/includes/Wiki.php(69): MediaWiki->performAction(Object(OutputPage), Object(Article), Object(Title), Object(User), Object(WebRequest)) #20 /var/www/ocw/mediawiki-1.17.1/index.php(114): MediaWiki->performRequestForTitle(Object(Title), Object(Article), Object(OutputPage), Object(User), Object(WebRequest)) #21 {main} Zero value for `Corresponds to' is a user mistake, but it should not cause SMW internal error with PHP stack dump. BTW, I faced with problem by a mistake. I wrote `[[Corresponds to::0.001 km]]'. Looks pretty good, doesn't? But MW content language specifies decimal separator as comma, so `0.001 km' is parsed as number `0' and unit `.0001 km'. However, no warning or errors are show on property page. Instead, it causes stack dump on another page…
Yeah... SMW should drop Corresponds to 0 values and show a warning that it's doing this.
Fixed in r111248. A warning is not shown though. I don't think this is really necessary in practice.
Guys, I spend noticeable part of my life hunting for the bugs in software. I *know* -- good error messages and warnings are REALLY NECESSARY! Look into the case again: [[Corresponds to::0.001 km]] It looks perfect! Trouble appears in another page. It was PHP exception before, not to good, but at least it was the obvious signal that something goes wrong. Now you *silently* ignore it, so users will spend hours trying to understand why `Corresponds to' DOES NOT WORK. They will be frustrated, they will apply for help, send messages to Semediawiki-user, and other people will spend time again... Why? Ok, why do you show warnings if property value is invalid? For example: [[Coordinates::foo]] (where property `Coordinates' is of type `Geographic coordinate') will show small yellow triangle with exclamation sing and bubble "Failed to parse geographic coordinate: foo"? This is exactly the same case! User set property `Corresponds to' to value which is not understood. Why invalid value of `Coordinates' property shows warning, but `Corresponds to' -- does not? If you think it is not really necessary, let us drop all the warnings.
