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  • Model login constraints based on time

    - by DaDaDom
    Good morning, for an existing web application I need to implement "time based login constraints". It means that for each user, later maybe each group, I can define timeslots when they are (not) allowed to log in into the system. As all data for the application is stored in database tables, I need to somehow create a way to model this idea in that way. My first approach, I will try to explain it here: Create a tree of login constraints (called "timeslots") with the main "categories", like "workday", "weekend", "public holiday", etc. on the top level, which are in a "sorted" order (meaning "public holiday" has a higher priority than "weekday") for each top level node create subnodes, which have a finer timespan, like "monday", "tuesday", ... below that, create an "hour" level: 0, 1, 2, ..., 23. No further details are necessary. set every member to "allowed" by default For every member of the system create a 1:n relationship member:timeslots which defines constraints, e.g. a member A may have A:monday-forbidden and A:tuesday-forbidden Do a depth-first search at every login and check if the member has a constraint. Why a depth first search? Well, I thought that it may be that a member has the rules: A:monday->forbidden, A:monday-10->allowed, A:mondey-11->allowed So a login on monday at 12:30 would fail, but one at 10:30 succeed. For performance reasons I could break the relational database paradigm and set a flag for every entry in the member-to-timeslots-table which is set to true if the member has information set for "finer" timeslots, but that's a second step. Is this model in principle a good idea? Are there existing models? Thanks.

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  • How to not specify ruleset name when reading from config file?

    - by user102533
    When I read rules from a configuration file, I do something like this: IConfigurationSource configurationSource = new FileConfigurationSource("myvalidation.config"); var validator = ValidationFactory.CreateValidator<Salary>(configurationSource); The config file looks like this: <ruleset name="Default"> <properties> <property name="Address"> <validator lowerBound="10" lowerBoundType="Inclusive" upperBound="15" upperBoundType="Inclusive" negated="false" messageTemplate="" messageTemplateResourceName="" messageTemplateResourceType="" tag="" type="Microsoft.Practices.EnterpriseLibrary.Validation.Validators.StringLengthValidator, Microsoft.Practices.EnterpriseLibrary.Validation, Version=4.1.0.0, Culture=neutral, PublicKeyToken=null" name="String Length Validator" /> </property> </properties> </ruleset> My question is - is there a way to not specify the ruleset name? It's not required for me to specify a ruleset name if I am using the attribute approach and I can validate using: ValidationResults results = Validation.Validate(salary); Now when reading from config files, I have to specify the ruleset name. There is no overload of the CreateValidator method that accepts the configuration source without specifying the ruleset name. Also, the xml in the config file requires a name attribute for ruleset

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  • Replacement for deprecated SQL Server User Defined Type with a bound Rule and Default

    - by Adam Jones
    We have a User Defined Data Type of YesNo which has an which is an alias for char(1). The type has a bound Rule (must be Y or N) and a Default (N). The aim of this is that when any of the development team create a new field of type YesNo the rule and default are automatically bound to the new column. Rules and Defaults have been deprecated and won't be available in the next a future version of SQL Server, is there another way to achieve the same functionality? I should add that I'm aware that I could use CHECK and DEFAULT constraints to replicate the functionality of the bound Rule and Defalut objects, however these would have to be applied at each usage of the type, rather than getting the functionality 'for free' by using a UDT which has a bound Rule and Default. The post relates to a database that backs an existing application, rather than a new development, so I'm aware that our use of UDT's is less than optimal. I suspect the answer to the question is 'No', however normally when features are deprecated there's usually an alternative syntax that can be used as a drop in replacement so I wanted to pose the question in-case someone knew of an alternative.

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  • ASP.NET MVC UpdateModel doesn't update inherited public properties??

    - by mrjoltcola
    I refactored some common properties into a base class and immediately my model updates started failing. UpdateModel() and TryUpdateModel() do not seem to update inherited public properties. I cannot find detailed info on MSDN nor Google as to the rules or semantics of these methods. The docs are terse (http://msdn.microsoft.com/en-us/library/dd470933.aspx), simply stating: Updates the specified model instance using values from the controller's current value provider. Well that leads us to believe it is as simple as that. It makes no mention of limitations with inheritance. My assumption is the methods are reflecting on the top class only, ignoring base properties, but this seems to be an ugly shortcoming, if so. SOLVED: Eep, this turned out to have nothing to do with inheritance. My base class was implemented with public fields, not properties. Switching them to formal properties (adding {get; set; }) was all I needed. This has bitten me before, I keep wanting to use simple, public fields.

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  • If the address of a function can not be resolved during deduction, is it SFINAE or a compiler error?

    - by Faisal Vali
    In C++0x SFINAE rules have been simplified such that any invalid expression or type that occurs in the "immediate context" of deduction does not result in a compiler error but rather in deduction failure (SFINAE). My question is this: If I take the address of an overloaded function and it can not be resolved, is that failure in the immediate-context of deduction? (i.e is it a hard error or SFINAE if it can not be resolved)? Here is some sample code: struct X { // template T* foo(T,T); // lets not over-complicate things for now void foo(char); void foo(int); }; template struct S { template struct size_map { typedef int type; }; // here is where we take the address of a possibly overloaded function template void f(T, typename size_map::type* = 0); void f(...); }; int main() { S s; // should this cause a compiler error because 'auto T = &X::foo' is invalid? s.f(3); } Gcc 4.5 states that this is a compiler error, and clang spits out an assertion violation. Here are some more related questions of interest: Does the FCD-C++0x clearly specify what should happen here? Are the compilers wrong in rejecting this code? Does the "immediate-context" of deduction need to be defined a little better? Thanks!

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  • python-iptables: Cryptic error when allowing incoming TCP traffic on port 1234

    - by Lucas Kauffman
    I wanted to write an iptables script in Python. Rather than calling iptables itself I wanted to use the python-iptables package. However I'm having a hard time getting some basic rules setup. I wanted to use the filter chain to accept incoming TCP traffic on port 1234. So I wrote this: import iptc chain = iptc.Chain(iptc.TABLE_FILTER,"INPUT") rule = iptc.Rule() target = iptc.Target(rule,"ACCEPT") match = iptc.Match(rule,'tcp') match.dport='1234' rule.add_match(match) rule.target = target chain.insert_rule(rule) However when I run this I get this thrown back at me: Traceback (most recent call last): File "testing.py", line 9, in <module> chain.insert_rule(rule) File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1133, in insert_rule self.table.insert_entry(self.name, rbuf, position) File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1166, in new obj.refresh() File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1230, in refresh self._free() File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1224, in _free self.commit() File "/usr/local/lib/python2.6/dist-packages/iptc/__init__.py", line 1219, in commit raise IPTCError("can't commit: %s" % (self.strerror())) iptc.IPTCError: can't commit: Invalid argument Exception AttributeError: "'NoneType' object has no attribute 'get_errno'" in <bound method Table.__del__ of <iptc.Table object at 0x7fcad56cc550>> ignored Does anyone have experience with python-iptables that could enlighten on what I did wrong?

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  • OOP 101 - quick question.

    - by R Bennett
    I've used procedural for sometime now and trying to get a better understanding of OOP in Php. Starting at square 1 and I have a quick question ot get this to gel. Many of the basic examples show static values ( $bob-name = "Robert";) when assigning a value, but I want to pass values... say from a form ( $name = $_POST['name']; ) class Person { // define properties public $name; public $weight; public $age; public function title() { echo $this->name . " has submitted a request "; } } $bob = new Person; // want to plug the value in here $bob->name = $name; $bob->title(); I guess I'm getting a little hung up in some areas as far as accessing variables from within the class, encapsulation & "rules", etc., can $name = $_POST['name']; reside anywhere outside of the class or am I missing an important point? Thanks

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  • jQuery validate and tabs

    - by ntan
    Hi i am using jQuery validate for my form validation. The form is inside tabs.When i get an error i add an icon to the tab that error exist to be visual by the user So far so good. My problem is that after correct the error i can not remove the error in tab icon. I was assuming that validator is accessible via success but its not Assuming that the first tab (tab0) has 3 field for validation (field1,field2,field3) Here is the full code $("form#Form1") .validate({ invalidHandler: function(form, validator) { //TAB 0 if (validator.errorMap.field1 != "" && validator.errorMap.field2 != "" && validator.errorMap.field3 != "") { if ($("#tabs>ul>li").eq(0).find("img").length == 0) { $("#tabs>ul>li").eq(0).prepend("<img src=\"error.gif\">"); } } }, errorClass: "errorField", errorElement: "p", errorPlacement: function(error, element) { var parent = element.parent(); parent.addClass("error"); error.prependTo( parent ); }, //validator in not accessible via success //so my code its not working success: function(element,validator) { var parent = element.parent(); parent.removeClass("error"); $(parent).children("p.errorField").remove(); //TAB 0 if (validator.errorMap.field1 == "" && validator.errorMap.field2 == "" && validator.errorMap.field2 == "") { if ($("#tabs>ul>li").eq(0).find("img").length == 0) { $("#tabs>ul>li").eq(0).find("img").remove(); } } }, rules: { field1: { required: true }, field2: { required: true }, field3: { required: true } } }); Any suggestion is welcome.

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  • Thread-safe initialization of function-local static const objects

    - by sbi
    This question made me question a practice I had been following for years. For thread-safe initialization of function-local static const objects I protect the actual construction of the object, but not the initialization of the function-local reference referring to it. Something like this: namspace { const some_type& create_const_thingy() { lock my_lock(some_mutex); static const some_type the_const_thingy; return the_const_thingy; } } void use_const_thingy() { static const some_type& the_const_thingy = create_const_thingy(); // use the_const_thingy } The idea is that locking takes time, and if the reference is overwritten by several threads, it won't matter. I'd be interested if this is safe enough in practice? safe according to The Rules? (I know, the current standard doesn't even know what "concurrency" is, but what about trampling over an already initialized reference? And do other standards, like POSIX, have something to say that's relevant to this?) For the inquiring minds: Many such function-local static const objects I used are maps which are initialized from const arrays upon first use and used for lookup. For example, I have a few XML parsers where tag name strings are mapped to enum values, so I could later switch over the tags enum values.

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  • Biztalk vs API for databroker layer

    - by jdt199
    My company is about to undergo a large project in which our client wants a large customer portal with a cms, crm implementing. This will require interaction with data from multiple sources across our customers business, these sources include XML office backend systems, sql datbases, webservices etc. Our proposed solution would be to write an API in c# to provide a common interface with all these systems. This would be scalable for future and concurrent projects within the company. Our client expressed an interest in using Biztalk rather than a custom API for this integration, as they feel it is an enterprise solution that any of their suppliers could pick up and use, and it will be better supported. We feel that the configuration work using Biztalk would be rather heavy for all their custom business rules which are required and an interface for the new application to get data to and from Biztalk would still need to be written. Are we right to prefer a custom API solution above Biztalk? Would Biztalk be suitable as a databroker layer to provide an interface for the new Customer portal we are writing. We have not experience with using Biztalk before so any input would be appreciated.

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  • Jqgrid search option hides the grid table

    - by Felix Guerrero
    The issue is when I click on search option (on pager) it shows the search window but the grid gets hide. I'm including the jqmodal.js file. But what I'm ignoring on the code below? css files: jqModal.css jquery-ui-1.8.custom.css ui.jqgrid.css ui.multiselect.css jquery.searchFilter.css js files: jquery.min.js grid.base.js grid.common.js grid.formedit.js grid.setcolumns.js ui.multiselect.js jquery.searchFilter.js jqModal.js The Javascript: $("#list").jqGrid({ url: 'foo_report.php?g=' + $('#fooselect').val() + '&report=1&searchString=null&searchField=null&searchOper=null', datatype: 'json', mtype: 'GET', colNames: ['foo1','foo2', 'foo3'], colModel: [ { name:'rows.foobar1', index: 'foobar1', search:true, jsonmap: 'foobar1', width: 150, align: 'left', sortable:true}, { name:'rows.foobar2', index: 'foobar2', jsonmap: 'foobar2', width: 150, align: 'left'}, { name:'rows.foobar3', index: 'foobar3', jsonmap: 'foobar3', width: 240, align: 'left', sortable: true}], pager: '#pager', rowNum: 8, autowidth: true, rowList: [8, 16], sortname: 'foobar1', sortorder: 'asc', viewrecords: true, search : { caption: "Search...", Find: "Find", Reset: "Reset", odata : ['equal', 'not equal', 'less'], groupOps: [ { op: "AND", text: "all" }, { op: "OR", text: "any" }], matchText: " match", rulesText: " rules" }, caption: 'Foobar Data', jsonReader : { root: "rows", repeatitems: false }, height: 350, width: 800 }); html: <table id="list"></table> <div id="pager"></div>

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  • WPF - Why doesn't Microsoft supply a decent set of most-used controls ?

    - by IUsedToBeAPygmy
    I've been playing with WPF for some months now, and I quite like it. But one of the things I don't get is why MS doesn't put a little more effort in helping developers by supplying basic controls, and I need to get this off my chest :) For example, I figure most applications somewhere will need to let you edit some properties - for configuration or whatever. What would be the most used types in a proprety-grid editor ? text numbers (byte, float/double, int, etc) colors ....etc. So why isn't there even something as simple as a control to edit numbers ? Like a generic NumericUpDown control that allows you to type in numbers (no text, no pasting invalid input) or spin them up/down according to some given rules (decimal, floating point, min/maxvalue) ? Why isn't there a generic colorpicker, so people get the same user-experience in every application ? Why isn't there a standard implementation of a SearchTextBox, a BreadCrumb-control, or all these other standard control types users have gotten accustomed to the last 10 years ? (..but at least they DID have the time to implement a generic splashscreen - because everyone knows that greatly increases user-productivity....) The well-known ideal is always to give people the same user-experience over different applications. So even if some of those controls would be easy to make - it would be preferred to have one version over different applications. I see people all over the internet trying to do the same stuff over and over again. Okay, so MS started a WPF Toolkit project on Codeplex that tries to implement some controls, but only did so half-heartedly and is completely dead by now (last update of the roadmap dates back to Mar 21 2009). The result of this is that a lot of people starting a WPF-project end up spending a lot of time on trying to figure out how to create some generic controls and get really frustrated. Wasn't the mantra "Developers, developers, developers!" ..? /Rant

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  • C# Windows Service doesn't seem to like privatePath

    - by SauerC
    I wrote a C# Windows Service to handle task scheduling for our application. I'm trying to move the "business rules" assemblies into a bin subdirectory of the scheduling application to make it easier for us to do updates (stop service, delete all files in bin folder, replace with new ones, start service). I added <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <probing privatePath="bin;"/> </assemblyBinding> </runtime> to the service's app config and it works fine if the service is run as a console application. Problem is when the service is run as a windows service it doesn't work. It appears that when windows runs the service the app config file gets read properly but then the service is executed as if it was in c:\windows\system32 and not the actually EXE location and that gums up the works. We've got a lot of assemblies so I really don't want to use the GAC or <codeBase>. Is it possible to have the EXE change it's base directory back to where it should be when it's run as a service?

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  • SSIS - Bulk Update at Database Field Level

    - by Adam
    Hello, Here's our mission: Receive files from clients. Each file contains anywhere from 1 to 1,000,000 records. Records are loaded to a staging area and business-rule validation is applied. Valid records are then pumped into an OLTP database in a batch fashion, with the following rules: If record does not exist (we have a key, so this isn't an issue), create it. If record exists, optionally update each database field. The decision is made based on one of 3 factors...I don't believe it's important what those factors are. Our main problem is finding an efficient method of optionally updating the data at a field level. This is applicable across ~12 different database tables, with anywhere from 10 to 150 fields in each table (original DB design leaves much to be desired, but it is what it is). Our first attempt has been to introduce a table that mirrors the staging environment (1 field in staging for each system field) and contains a masking flag. The value of the masking flag represents the 3 factors. We've then put an UPDATE similar to... UPDATE OLTPTable1 SET Field1 = CASE WHEN Mask.Field1 = 0 THEN Staging.Field1 WHEN Mask.Field1 = 1 THEN COALESCE( Staging.Field1 , OLTPTable1.Field1 ) WHEN Mask.Field1 = 2 THEN COALESCE( OLTPTable1.Field1 , Staging.Field1 ) ... As you can imagine, the performance is rather horrendous. Has anyone tackled a similar requirement? We're a MS shop using a Windows Service to launch SSIS packages that handle the data processing. Unfortunately, we're pretty much novices at this stuff.

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  • String Manipulation: Splitting Delimitted Data

    - by Milli Szabo
    I need to split some info from a asterisk delimitted data. Data Format: NAME*ADRESS LINE1*ADDRESS LINE2 Rules: 1. Name should be always present 2. Address Line 1 and 2 might not be 3. There should be always three asterisks. Samples: MR JONES A ORTEGA*ADDRESS 1*ADDRESS2* Name: MR JONES A ORTEGA Address Line1: ADDRESS 1 Address Line2: ADDRESS 2 A PAUL*ADDR1** Name: A PAUL Address Line1: ADDR1 Address Line2: Not Given My algo is: 1. Iterate through the characters in the line 2. Store all chars in a temp variables until first * is found. Reject the data if no char is found before first occurence of asterisk. If some chars found, use it as the name. 3. Same as step 2 for finding address line 1 and 2 except that this won't reject the data if no char is found My algo looks ugly. The code looks uglier. Spliting using //* doesn't work either since name can be replaced with address line 1 if the data was *Address 1*Address2. Any suggestion?

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  • Creating search functionality with Laravel 4

    - by Mitch Glenn
    I am trying to create a way for users to search through all the products on a website. When they search for "burton snowboards", I only want the snowboards with the brand burton to appear in the results. But if they searched only "burton", then all products with the brand burton should appear. This is what I have attempted to write but isn't working for multiple reasons. Controller: public function search(){ $input = Input::all(); $v= Validator::make($input, Product::$rules); if($v->passes()) { $searchTerms = explode(' ', $input); $searchTermBits = array(); foreach ($searchTerms as $term) { $term = trim($term); if (!empty($term)){ $searchTermBits[] = "search LIKE '%$term%'"; } } $result = DB::table('products') ->select('*') ->whereRaw(". implode(' AND ', $searchTermBits) . ") ->get(); return View::make('layouts/search', compact('result')); } return Redirect::route('/'); } I am trying to recreate the first solution given for this stackoverflow.com problem The first problem I have identified is that i'm trying to explode the $input, but it's already an array. So i'm not sure how to go about fixing that. And the way I have written the ->whereRaw(". implode(' AND ', $searchTermBits) . "), i'm sure isn't correct. I'm not sure how to fix these problems though, any insights or solutions will be greatly appreciated.

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  • How do I pass parameters between request-scoped beans

    - by smayers81
    This is a question that has been bothering me for sometime. My application uses ICEFaces for our UI framework and Spring 2.5 for Dependency Injection. In addition, Spring actually maintains all of our backing beans, not the ICEFaces framework, so our faces-config is basically empty. Navigation is not even really handled through navigation-rules. We perform manual redirects to new windows using window.open. All of our beans are defined in our appContext file as being request-scoped. I have Page ABC which is backed by BackingBeanABC. Inside that backing bean, I have a parameter say: private Order order; I then have Page XYZ backed by BackingBeanXYZ. When I redirect from page ABC to page XYZ, I want to transfer the 'order' property from ABC to XYZ. The problem is since everything is request-scoped and I'm performing a redirect, I am losing the value of 'description'. There has got to be an easier way to pass objects between beans in request scope during a redirect. Can anyone assist with this issue?

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  • Host Primary Domain from a subfolder

    - by TandemAdam
    I am having a problem making a sub directory act as the public_html for my main domain, and getting a solution that works with that domains sub directories too. My hosting allows me to host multiple sites, which are all working great. I have set up a subfolder under my ~/public_html/ directory called /domains/, where I create a folder for each separate website. e.g. public_html domains websiteone websitetwo websitethree ... This keeps my sites nice and tidy. The only issue was getting my "main domain" to fit into this system. It seems my main domain, is somehow tied to my account (or to Apache, or something), so I can't change the "document root" of this domain. I can define the document roots for any other domains ("Addon Domains") that I add in cPanel no problem. But the main domain is different. I was told to edit the .htaccess file, to redirect the main domain to a subdirectory. This seemed to work great, and my site works fine on it's home/index page. The problem I'm having is that if I try to navigate my browser to say the images folder (just for example) of my main site, like this: www.yourmaindomain.com/images/ then it seems to ignore the redirect and shows the entire server directory in the url, like this: www.yourmaindomain.com/domains/yourmaindomain/images/ It still actually shows the correct "Index of /images" page, and show the list of all my images. Here is an example of my .htaccess file that I am using: RewriteEngine on RewriteCond %{HTTP_HOST} ^(www.)?yourmaindomain.com$ RewriteCond %{REQUEST_URI} !^/domains/yourmaindomain/ RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)$ /domains/yourmaindomain/$1 RewriteCond %{HTTP_HOST} ^(www.)?yourmaindomain.com$ RewriteRule ^(/)?$ domains/yourmaindomain/index.html [L] Does this htaccess file look correct? I just need to make it so my main domain behaves like an addon domain, and it's subdirectories adhere to the redirect rules.

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  • Bidirectional replication update record problem

    - by Mirek
    Hi, I would like to present you my problem related to SQL Server 2005 bidirectional replication. What do I need? My teamleader wants to solve one of our problems using bidirectional replication between two databases, each used by different application. One application creates records in table A, changes should replicate to second database into a copy of table A. When data on second server are changed, then those changes have to be propagated back to the first server. I am trying to achieve bidirectional transactional replication between two databases on one server, which is running SQL Server 2005. I have manage to set this up using scripts, established 2 publications and 2 read only subscriptions with loopback detection. Distributtion database is created, publishment on both databases is enabled. Distributor and publisher are up. We are using some rules to control, which records will be replicated, so we need to call our custom stored procedures during replication. So, articles are set to use update, insert and delete custom stored procedures. So far so good, but? Everything works fine, changes are replicating, until updates are done on both tables simultaneously or before changes are replicated (and that takes about 3-6 seconds). Both records then end up with different values. UPDATE db1.dbo.TestTable SET Col = 4 WHERE ID = 1 UPDATE db2.dbo.TestTable SET Col = 5 WHERE ID = 1 results to: db1.dbo.TestTable COL = 5 db2.dbo.TestTable COL = 4 But we want to have last change winning replication. Please, is there a way to solve my problem? How can I ensure same values in both records? Or is there easier solution than this kind of replication? I can provide sample replication script which I am using. I am looking forward for you ideas, Mirek

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  • JQuery Validate: only takes the first addMethod?

    - by Neuquino
    Hi, I need to add multiple custom validations to one form. I have 2 definitions of addMethod. But it only takes the first one... here is the code. $(document).ready(function() { $.validator.addMethod("badSelectionB",function(){ var comboValues = []; for(var i=0;i<6;i++){ var id="comision_B_"+(i+1); var comboValue=document.getElementById(id).value; if($.inArray(comboValue,comboValues) != 0){ comboValues.push(comboValue); }else{ return false; } } return true; },"Seleccione una única prioridad por comisión."); $.validator.addMethod("badSelectionA",function(){ var comboValues = []; for(var i=0;i<6;i++){ var id="comision_A_"+(i+1); var comboValue=document.getElementById(id).value; if($.inArray(comboValue,comboValues) != 0){ comboValues.push(comboValue); }else{ return false; } } return true; },"Seleccione una única prioridad por comisión."); $("#inscripcionForm").validate( { rules : { nombre : "required", apellido : "required", dni : { required: true, digits: true, }, mail : { required : true, email : true, }, comision_A_6: { badSelectionA:true, }, comision_B_6: { badSelectionB: true, } }, messages : { nombre : "Ingrese su nombre.", apellido : "Ingrese su apellido.", dni : { required: "Ingrese su dni.", digits: "Ingrese solo números.", }, mail : { required : "Ingrese su correo electrónico.", email: "El correo electrónico ingresado no es válido." } }, }); }); Do you have any clue of what is happening? Thanks in advance,

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  • howto distinguish composition and self-typing use-cases

    - by ayvango
    Scala has two instruments for expressing object composition: original self-type concept and well known trivial composition. I'm curios what situations I should use which in. There are obvious differences in their applicability. Self-type requires you to use traits. Object composition allows you to change extensions on run-time with var declaration. Leaving technical details behind I can figure two indicators to help with classification of use cases. If some object used as combinator for a complex structure such as tree or just have several similar typed parts (1 car to 4 wheels relation) than it should use composition. There is extreme opposite use case. Lets assume one trait become too big to clearly observe it and it got split. It is quite natural that you should use self-types for this case. That rules are not absolute. You may do extra work to convert code between this techniques. e.g. you may replace 4 wheels composition with self-typing over Product4. You may use Cake[T <: MyType] {part : MyType} instead of Cake { this : MyType => } for cake pattern dependencies. But both cases seem counterintuitive and give you extra work. There are plenty of boundary use cases although. One-to-one relations is very hard to decide with. Is there any simple rule to decide what kind of technique is preferable? self-type makes you classes abstract, composition makes your code verbose. self-type gives your problems with blending namespaces and also gives you extra typing for free (you got not just a cocktail of two elements but gasoline-motor oil cocktail known as a petrol bomb). How can I choose between them? What hints are there? Update: Let us discuss the following example: Adapter pattern. What benefits it has with both selt-typing and composition approaches?

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  • Making Javascript and HTML5 games

    - by Jeff Meatball Yang
    A long time ago (Netscape 4-era), I wrote Javascript-based games: Pong, Minesweeper, and John Conway's Life among them. I'm getting back into it, and want to get my hands even dirtier. I have a few games in mind: Axis & Allies clone, with rugged maps and complex rules. Tetris clone, possibly with real-time player-vs-player or player-vs-computer mode Breakout clone, with a couple weapons and particle velocities In all of these, I have only a few objectives: Use JavaScript and HTML 5 - it should run on Chrome, Safari, or maybe an iPad. Start small and simple, then build-up features. Learn something new about game design and implementation. So my questions are: How would you implement these games? Do you have any technology recommendations? If you've written these games, what was the hardest part? N.B. I also want to start from first-principles - if you recommend a framework/library, I would appreciate some theory or implementation details behind it. These games are different enough that I should learn something new from each one.

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  • Unit tests - The benefit from unit tests with contract changes?

    - by Stefan Hendriks
    Recently I had an interesting discussion with a colleague about unit tests. We where discussing when maintaining unit tests became less productive, when your contracts change. Perhaps anyone can enlight me how to approach this problem. Let me elaborate: So lets say there is a class which does some nifty calculations. The contract says that it should calculate a number, or it returns -1 when it fails for some reason. I have contract tests who test that. And in all my other tests I stub this nifty calculator thingy. So now I change the contract, whenever it cannot calculate it will throw a CannotCalculateException. My contract tests will fail, and I will fix them accordingly. But, all my mocked/stubbed objects will still use the old contract rules. These tests will succeed, while they should not! The question that rises, is that with this faith in unit testing, how much faith can be placed in such changes... The unit tests succeed, but bugs will occur when testing the application. The tests using this calculator will need to be fixed, which costs time and may even be stubbed/mocked a lot of times... How do you think about this case? I never thought about it thourougly. In my opinion, these changes to unit tests would be acceptable. If I do not use unit tests, I would also see such bugs arise within test phase (by testers). Yet I am not confident enough to point out what will cost more time (or less). Any thoughts?

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  • Flex build error

    - by incrediman
    I'm totally new to flex. I'm getting a build error when using flex. That is, I've generated a .c file using flex, and, when running it, am getting this error: 1>lextest.obj : error LNK2001: unresolved external symbol "int __cdecl isatty(int)" (?isatty@@YAHH@Z) 1>C:\...\lextest.exe : fatal error LNK1120: 1 unresolved externals here is the lex file I'm using (grabbed from here): /*** Definition section ***/ %{ /* C code to be copied verbatim */ #include <stdio.h> %} /* This tells flex to read only one input file */ %option noyywrap %% /*** Rules section ***/ /* [0-9]+ matches a string of one or more digits */ [0-9]+ { /* yytext is a string containing the matched text. */ printf("Saw an integer: %s\n", yytext); } . { /* Ignore all other characters. */ } %% /*** C Code section ***/ int main(void) { /* Call the lexer, then quit. */ yylex(); return 0; } As well, why do I have to put a 'main' function in the lex syntax code? What I'd like is to be able to call yylex(); from another c file.

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  • why does this boost::spirit::qi rule not work?

    - by Tobias Langner
    I have a grammar that defines the following rules: constantValue = qi::token(ID_FLOAT) | qi::token(ID_INTEGER); postfixExpression = primaryExpression | (postfixExpression >> qi::token(ID_OPENBRACKET) >> qi::token(ID_INTEGER) >> qi::token(ID_CLOSEBRACKET)) | (postfixExpression >> qi::token(ID_DOT) >> qi::token(ID_IDENTIFIER)); primaryExpression = qi::token(ID_IDENTIFIER) | constantValue | (qi::token(ID_OPENPAREN) >> primaryExpression >> qi::token(ID_CLOSEPAREN)); ges = postfixExpression >> qi::eoi; and I want it to match the following strings: test[1] testident.ident and it should not match test[1.2] testident.5 but it fails to match the first 2 strings. The lexer constructor is as follows: custom_lexer() : identifier("[a-zA-Z_][a-zA-Z0-9_]*") , white_space("[ \\t\\n]+") , integer_value("[1-9][0-9]*") , hex_value("0[xX][0-9a-fA-F]+") , float_value("[0-9]*\\.[0-9]+([eE][+-]?[0-9]+)?") , float_value2("[0-9]+\\.([eE][+-]?[0-9]+)?") , punctuator("&>|\\*\\*|\\*|\\+|-|~|!|\\/|%|<<|>>|<|>|<=|>=|==|!=|\\^|&|\\||\\^\\^|&&|\\|\\||\\?|:|,")// [ ] ( ) . &> ** * + - ~ ! / % << >> < > <= >= == != ^ & | ^^ && || ? : , { using boost::spirit::lex::_start; using boost::spirit::lex::_end; this->self.add (identifier, ID_IDENTIFIER) /*(white_space, ID_WHITESPACE)*/ (integer_value, ID_INTEGER) (hex_value, ID_INTEGER) (float_value, ID_FLOAT) (float_value2, ID_FLOAT) ("\\(", ID_OPENPAREN) ("\\)", ID_CLOSEPAREN) ("\\[", ID_OPENBRACKET) ("\\]", ID_CLOSEBRACKET) ("\\.", ID_DOT) (punctuator, ID_PUNCTUATOR) ; this->self("WS") = white_space; } Why don't I get a match for the mentioned strings? Thank you Tobias

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