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  • Strategies for avoiding SQL in your Controllers... or how many methods should I have in my Models?

    - by Keith Palmer
    So a situation I run into reasonably often is one where my models start to either: Grow into monsters with tons and tons of methods OR Allow you to pass pieces of SQL to them, so that they are flexible enough to not require a million different methods For example, say we have a "widget" model. We start with some basic methods: get($id) insert($record) update($id, $record) delete($id) getList() // get a list of Widgets That's all fine and dandy, but then we need some reporting: listCreatedBetween($start_date, $end_date) listPurchasedBetween($start_date, $end_date) listOfPending() And then the reporting starts to get complex: listPendingCreatedBetween($start_date, $end_date) listForCustomer($customer_id) listPendingCreatedBetweenForCustomer($customer_id, $start_date, $end_date) You can see where this is growing... eventually we have so many specific query requirements that I either need to implement tons and tons of methods, or some sort of "query" object that I can pass to a single -query(query $query) method... ... or just bite the bullet, and start doing something like this: list = MyModel-query(" start_date X AND end_date < Y AND pending = 1 AND customer_id = Z ") There's a certain appeal to just having one method like that instead of 50 million other more specific methods... but it feels "wrong" sometimes to stuff a pile of what's basically SQL into the controller. Is there a "right" way to handle situations like this? Does it seem acceptable to be stuffing queries like that into a generic -query() method? Are there better strategies?

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  • Anemic Domain Model, Business Logic and DataMapper (PHP)

    - by sunwukung
    I've implemented a rudimentary ORM layer based on DataMapper (I don't want to use a full blown ORM like Propel/Doctrine - for anything beyond simple fetch/save ops I prefer to access the data directly layer using a SQL abstraction layer). Following the DataMapper pattern, I've endeavoured to keep all persistence operations in the Mapper - including the location of related entities. My Entities have access to their Mapper, although I try not to call Mapper logic from the Entity interface (although this would be simple enough). The result is: // get a mapper and produce an entity $ProductMapper = $di->get('product_mapper'); $Product = $ProductMapper->find('[email protected]','email'); //.. mutaute some values.. save $ProductMapper->save($Product) // uses __get to trigger relation acquisition $Manufacturer = $Product->manufacturer; I've read some articles regarding the concept of an Anemic Domain model, i.e. a Model that does not contain any "business logic". When demonstrating the sort of business logic ideally suited to a Domain Model, however, acquiring related data items is a common example. Therefore I wanted to ask this question: Is persistence logic appropriate in Domain Model objects?

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  • Avoiding null in a controller

    - by Kevin Burke
    I'm trying to work through how to write this code. def get(params): """ Fetch a user's details, or 404 """ user = User.fetch_by_id(params['id']) if not user: abort(404) # Render some template for the user... What's the best way to handle the case where the lookup fails? One principle says you should avoid returning null values from functions. These lead to mistakes and AttributeErrors etc. later on in the file. Another idea is to have fetch_by_id raise a ValueError or similar if no user exists with that id. However there's a general principle that you shouldn't use exceptions for control flow, either, which doesn't help much. What could be done better in this case?

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  • How important is index size when searching?

    - by Michael K
    My company has recently began using Apache Solr to search its data. As we learn how to use it we have gone down the path of indexing multiple fields to get the results we need. Most of these are either N-Grammed or Edge-N-Grammed. Gramming by nature takes up a lot of space, which takes more time to search. Space is cheap, but time is less so. Index time is not too important, since a delta-import (only get the changes since last index) is extremely quick and you only pay a penalty on the first import. What we've not been able to determine is what effect the index size has on query times. Obviously a larger index takes longer to search, but the time added by n-gramming a field is difficult to predict. How do you determine whether a field is worth gramming? Can you predict how much longer a query will take when you gram a field?

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  • Updating and organizing class diagrams in a growing C++ project

    - by vanna
    I am working on a C++ project that is getting bigger and bigger. I do a lot of UML so it is not really hard to explain my work to co-workers. Lately though I implemented a lot of new features and I gave up updating by hand my Dia UML diagrams. I once used the class diagram of Visual Studio, which is my IDE but didn't get clear results. I need to show my work on a regular basis and I would like to be as clear as possible. Is there any tool that could generate a sort of organized map of my work (namespaces, classes, interactions, etc.) ?

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  • Creating meaningful and engaging quests

    - by user384918
    Kill X number of monsters. Gather Y number of items (usually by killing X number of monsters). Deliver this NPC's package to this other NPC who is far far away. etc. Yeah. These quests are easy to implement, easy to complete, but also very boring after the first few times. It's kind of disingenuous to call them quests really; they're more like chores or errands. What ideas for quests have people seen that were well designed, immersive, and rewarding? What specific things did the developers do that made it so? What are some ideas you would use (or have used) to make quests more interesting?

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  • Single Responsibility Principle: Responsibility unknown

    - by lurkerbelow
    I store sessions in a SessionManager. The session manager has a dependency to ISessionPersister. SessionManager private readonly ISessionPersister sessionPersister; public SessionManager(ISessionPersister sessionPersister) { this.sessionPersister = sessionPersister; } ISessionPersister public interface ISessionPersister : IDisposable { void PersistSessions(Dictionary<string, ISession> sessions); } Q: If my application shuts down how / where do I call PersistSessions? Who is responsible? First Approach: Use Dispose in SessionManager protected virtual void Dispose(bool disposing) { if (disposing) { if (this.sessionPersister != null && this.sessionMap != null && this.sessionMap.Count > 0) { this.sessionPersister.PersistSessions(this.sessionMap); } } } Is that the way to go or are there any better solutions?

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  • Extension objects pattern

    - by voroninp
    In this MSDN Magazine article Peter Vogel describes Extension Objects partten. What is not clear is whether extensions can be later implemented by client code residing in a separate assembly. And if so how in this case can extension get acces to private members of the objet being extended? I quite often need to set different access levels for different classes. Sometimes I really need that descendants does not have access to the mebmer but separate class does. (good old friend classes) Now I solve this in C# by exposing callback properties in interface of the external class and setting them with private methods. This also alows to adjust access: read only or read|write depending on the desired interface. class Parent { private int foo; public void AcceptExternal(IFoo external) { external.GetFooCallback = () => this.foo; } } interface IFoo { Func<int> GetFooCallback {get;set;} } Other way is to explicitly implement particular interface. But I suspect more aspproaches exist.

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  • Dynamic Query Generation : suggestion for better approaches

    - by Gaurav Parmar
    I am currently designing a functionality in my Web Application where the verified user of the application can execute queries which he wishes to from the predefined set of queries with where clause varying as per user's choice. For example,Table ABC contains the following Template query called SecretReport "Select def as FOO, ghi as BAR from MNO where " SecretReport can have parameters XYZ, ILP. Again XYZ can have values as 1,2 and ILP can have 3,4 so if the user chooses ILP=3, he will get the result of the following query on his screen "Select def as FOO, ghi as BAR from MNO where ILP=3" Again the user is allowed permutations of XYZ / ILP My initial thought is that User will be shown a list of Report names and each report will have parameters and corresponding values. But this approach although technically simple does not appear intuitive. I would like to extend this functionality to a more generic level. Such that the user can choose a table and query based on his requirements. Of course we do not want the end user to take complete control of DB. But only tables and fields that are relevant to him. At present we are defining what is relevant in the code. But I want the Admin to take over this functionality such that he can decide what is relevant and expose the same to the user. On user's side it should be intuitive what is available to him and what queries he can form. Please share your thoughts what is the most user friendly way to provide this feature to the end user.

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  • IoC containers and service locator pattern

    - by TheSilverBullet
    I am trying to get an understanding of Inversion of Control and the dos and donts of this. Of all the articles I read, there is one by Mark Seemann (which is widely linked to in SO) which strongly asks folks not to use the service locator pattern. Then somewhere along the way, I came across this article by Ken where he helps us build our own IoC. I noticed that is is nothing but an implementation of service locator pattern. Questions: Is my observation correct that this implementation is the service locator pattern? If the answer to 1. is yes, then Do all IoC containers (like Autofac) use the service locator pattern? If the answer to 1. is no, then why is this differen? Is there any other pattern (other than DI) for inversion of control?

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  • Upgrading an app to support iOS5, 6 and 7

    - by drekka
    We are looking at an app that needs an upgrade. Currently it runs on iOS4, 5 & 6. The upgrade will move to iOS5, 6 & 7. It will also involve some UI changes and new features. I've been reading stuff on iOS7 and looking at things like auto-layout. What we are trying to figure out is the best way to handle the differences between the various iOS versions. Auto-layout seems like a good idea, but it's not available on iOS 5. There are also API changes to consider between all 3 versions and other new features of iOS7. So the questions: How would you handle auto layout given iOS5 does not have it? Are there any significant differences between the SDKs that you think would cause issues? Would we be better off with separate code bases?

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  • Should one use a separate database for application data and user data?

    - by trycatch
    I’ve been working on a project for a little while and I’m unsure which is the better architecture. I’m interested in the consensus. The answer to me seems fairly obvious but something about it is digging at me and I can't pick out what. The TL;DR is: how do you handle a program with application data and user data in the same DB which needs to be able to receive updates to the application data periodically? One database for user data and one for application, or both in one? The detailed version is.. if an application has a database which needs to maintain application data AND user data, and the user data all references application data, it feels more natural to me to store them in the same database. But if there exists a need to be able to update the application data within this database periodically, should this be stripped into two databases so that one can simply download the updated application data database file as an update and replace the old one? Or should they remain as one database, and the application data be updated via a script which inserts the new data into the existing database? The second sounds clearly preferable to me... but for some reason just doesn’t feel right, and I can't pick out quite why.

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  • python factory function best practices

    - by Jason S
    Suppose I have a file foo.py containing a class Foo: class Foo(object): def __init__(self, data): ... Now I want to add a function that creates a Foo object in a certain way from raw source data. Should I put it as a static method in Foo or as another separate function? class Foo(object): def __init__(self, data): ... # option 1: @staticmethod def fromSourceData(sourceData): return Foo(processData(sourceData)) # option 2: def makeFoo(sourceData): return Foo(processData(sourceData)) I don't know whether it's more important to be convenient for users: foo1 = foo.makeFoo(sourceData) or whether it's more important to maintain clear coupling between the method and the class: foo1 = foo.Foo.fromSourceData(sourceData)

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  • How much game dev does $x amount of money get you?

    - by Frank
    How much a game costs to make gets asked often and is always answered with it depends or varies on the quality of the game. Well this is basically the same question but is a bit more precise. I'm wonder what quality of game you can make with varying degrees of funds. Lets say 500k, 1m, 2m, 5m, 10m, 15m, and 20m. Let's assume you don't do any of it yourself and it only covers development only... no advertising or manufacturing.

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  • Logic or Algorithm to solve this problem [closed]

    - by jade
    I have two lists. List1 {a,b,c,d,e} and List2 {f,g,h,i,j} The relation between the two list is as follows a->g,a->h,h->c,h->d,d->i,d->j Now I have these two lists displayed. Based on the relation above on selecting element a from List1, List2 shows g,h. On selecting h from List2, in List1 c,d are shown in List1. On selecting d from List1 it shows i,j in List2. How to trace back to initial state by deselecting the elements in reverse order in which they have been selected?

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  • find and replace app for ms word

    - by kittensatplay
    i program in python. i want to know if a program in python will work for ms word since ms word is not open source. the program basically changes words like ms word already does BUT it changes words based of off a list you write, which from what i know ms word doesnt do. if it does, just let me know. if there is a related program that is needed for a program in python or any language to work with a closed source software, jsut let me know.b also you can link to a phython specific place to ask phython related question if you know of one since im going to have a lot more in the future

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  • How does URL Rewriting affect SEO?

    - by Costa
    The following paragraph is from SEO Google Guide Google is good at crawling all types of URL structures, even if they're quite complex, but spending the time to make your URLs as simple as possible for both users and search engines can help. Some webmasters try to achieve this by rewriting their dynamic URLs to static ones; while Google is fine with this, we'd like to note that this is an advanced procedure and if done incorrectly, could cause crawling issues with your site. What makes URL re-writing implementation incorrect for GoogleBot? I am using Asp.net 3.5 framework.

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  • How do I create a game that runs on Windows, iOS and Android?

    - by AspaApps
    I use C++ to create windows games and now I want to step into another other OS like Android or iOS. I'm totally familiar with C++ so I tried to create app for iOS using objective C it was working awesome. However, I also want to publish games for Android but not by using Java. I don't want to create a single game 5-6 times for other platforms. Is their any way that if I create game for Windows then it will work in Android and iOS ? Or should I use Action Script 3.0? If I use action script 3.0, will it require Flash player to run the game in Windows, Android, iOS?

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  • django/python: is one view that handles two separate models a good idea?

    - by clime
    I am using django multi-table inheritance: Video and Image are models derived from Media. I have implemented two views: video_list and image_list, which are just proxies to media_list. media_list returns images or videos (based on input parameter model) for a certain object, which can be of type Event, Member, or Crag. It alters its behaviour based on input parameter action, which can be either "edit" or "view". The problem is that I need to ask whether the input parameter model contains Video or Image in media_list so that I can do the right thing. Similar condition is also in helper method media_edit_list that is called from the view. I don't particularly like it but the only alternative I can think of is to have separate logic for video_list and image_list and then probably also separate helper methods for videos and images: video_edit_list, image_edit_list, video_view_list, image_view_list. So four functions instead of just two. That I like even less because the video functions would be very similar to the respective image functions. What do you recommend? Here is extract of relevant parts: http://pastebin.com/07t4bdza. I'll also paste the code here: #urls url(r'^media/images/(?P<rel_model_tag>(event|member|crag))/(?P<rel_object_id>\d+)/(?P<action>(view|edit))/$', views.video_list, name='image-list') url(r'^media/videos/(?P<rel_model_tag>(event|member|crag))/(?P<rel_object_id>\d+)/(?P<action>(view|edit))/$', views.image_list, name='video-list') #views def image_list(request, rel_model_tag, rel_object_id, action): return media_list(request, Image, rel_model_tag, rel_object_id, action) def video_list(request, rel_model_tag, rel_object_id, action): return media_list(request, Video, rel_model_tag, rel_object_id, action) def media_list(request, model, rel_model_tag, rel_object_id, action): rel_model = tag_to_model(rel_model_tag) rel_object = get_object_or_404(rel_model, pk=rel_object_id) if model == Image: star_media = rel_object.star_image else: star_media = rel_object.star_video filter_params = {} if rel_model == Event: filter_params['media__event'] = rel_object_id elif rel_model == Member: filter_params['media__members'] = rel_object_id elif rel_model == Crag: filter_params['media__crag'] = rel_object_id media_list = model.objects.filter(~Q(id=star_media.id)).filter(**filter_params).order_by('media__date_added').all() context = { 'media_list': media_list, 'star_media': star_media, } if action == 'edit': return media_edit_list(request, model, rel_model_tag, rel_model_id, context) return media_view_list(request, model, rel_model_tag, rel_model_id, context) def media_view_list(request, model, rel_model_tag, rel_object_id, context): if request.is_ajax(): context['base_template'] = 'boxes/base-lite.html' return render(request, 'media/list-items.html', context) def media_edit_list(request, model, rel_model_tag, rel_object_id, context): if model == Image: get_media_record = get_image_record else: get_media_record = get_video_record media_list = [get_media_record(media, rel_model_tag, rel_object_id) for media in context['media_list']] if context['star_media']: star_media = get_media_record(star_media, rel_model_tag, rel_object_id) star_media['starred'] = True else: star_media = None json = simplejson.dumps({ 'star_media': star_media, 'media_list': media_list, }) return HttpResponse(json, content_type=json_response_mimetype(request)) # models class Media(models.Model, WebModel): title = models.CharField('title', max_length=128, default='', db_index=True, blank=True) event = models.ForeignKey(Event, null=True, default=None, blank=True) crag = models.ForeignKey(Crag, null=True, default=None, blank=True) members = models.ManyToManyField(Member, blank=True) added_by = models.ForeignKey(Member, related_name='added_images') date_added = models.DateTimeField('date added', auto_now_add=True, null=True, default=None, editable=False) def __unicode__(self): return self.title def get_absolute_url(self): return self.image.url if self.image else self.video.embed_url class Image(Media): image = ProcessedImageField(upload_to='uploads', processors=[ResizeToFit(width=1024, height=1024, upscale=False)], format='JPEG', options={'quality': 75}) thumbnail_1 = ImageSpecField(source='image', processors=[SmartResize(width=178, height=134)], format='JPEG', options={'quality': 75}) thumbnail_2 = ImageSpecField(source='image', #processors=[SmartResize(width=256, height=192)], processors=[ResizeToFit(height=164)], format='JPEG', options={'quality': 75}) class Video(Media): url = models.URLField('url', max_length=256, default='') embed_url = models.URLField('embed url', max_length=256, default='', blank=True) author = models.CharField('author', max_length=64, default='', blank=True) thumbnail = ProcessedImageField(upload_to='uploads', processors=[ResizeToFit(width=1024, height=1024, upscale=False)], format='JPEG', options={'quality': 75}, null=True, default=None, blank=True) thumbnail_1 = ImageSpecField(source='thumbnail', processors=[SmartResize(width=178, height=134)], format='JPEG', options={'quality': 75}) thumbnail_2 = ImageSpecField(source='thumbnail', #processors=[SmartResize(width=256, height=192)], processors=[ResizeToFit(height=164)], format='JPEG', options={'quality': 75}) class Crag(models.Model, WebModel): name = models.CharField('name', max_length=64, default='', db_index=True) normalized_name = models.CharField('normalized name', max_length=64, default='', editable=False) type = models.IntegerField('crag type', null=True, default=None, choices=crag_types) description = models.TextField('description', default='', blank=True) country = models.ForeignKey('country', null=True, default=None) #TODO: make this not null when db enables it latitude = models.FloatField('latitude', null=True, default=None) longitude = models.FloatField('longitude', null=True, default=None) location_index = FixedCharField('location index', length=24, default='', editable=False, db_index=True) # handled by db, used for marker clustering added_by = models.ForeignKey('member', null=True, default=None) #route_count = models.IntegerField('route count', null=True, default=None, editable=False) date_created = models.DateTimeField('date created', auto_now_add=True, null=True, default=None, editable=False) last_modified = models.DateTimeField('last modified', auto_now=True, null=True, default=None, editable=False) star_image = models.OneToOneField('Image', null=True, default=None, related_name='star_crags', on_delete=models.SET_NULL) star_video = models.OneToOneField('Video', null=True, default=None, related_name='star_crags', on_delete=models.SET_NULL)

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  • Progressbar patterns (Eclipse)

    - by JesperE
    I've struggled quite a bit with Eclipse and progress-monitors to try to have good progressbars which report useful progress information to the user. Inevitably the code gets cluttered with lots of things like if (monitor.isCancelled()) return; ... lengthyMethodCall(monitor.newChild(10)); and all over the place I need to pass a IProgressMonitor as an argument to my methods. This is bad, for several reasons: The code gets cluttered with lots of code which is not relevant to what the function actually does. I need to manually guesstimate which parts of the code takes time, and which parts do not. It interacts badly with automated tests; where much of the information which goes into a progressbar instead should be logged for later inspection. Is there a way out of this? Are there tools which can help me out with one or more of these problems? Should I be looking at Aspect-Oriented Programming tools, or are there other alternatives?

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  • Advice on reconciling discordant data

    - by Justin
    Let me support my question with a quick scenario. We're writing an app for family meal planning. We'll produce daily plans with a target calorie goal and meals to achieve it for our nuclear family. Our calorie goal will be calculated for each person from their attributes (gender, age, weight, activity level). The weight attribute is the simplest example here. When Dad (the fascist nerd who is inflicting this on his family) first uses the application he throws approximate values into it for Daughter. He thinks she is 5'2" (157 cm) and 125 lbs (56kg). The next day Mom sits down to generate the menu and looks back over what the bumbling Dad did, quietly fumes that he can never recall anything about the family, and says the value is really 118 lbs! This is the first introduction of the discord. It seems, in this scenario, Mom is probably more correct that Dad. Though both are only an approximation of the actual value. The next day the dear Daughter decides to use the program and sees her weight listed. With the vanity only a teenager could muster she changes the weight to 110 lbs. Later that day the Mom returns home from a doctor's visit the Daughter needed and decides that it would be a good idea to update her Daughter's weight in the program. Hooray, another value, this time 117 lbs. Now how do you reconcile these data points? Measurement error, confidence in parties, bias, and more all confound the data. In some idealized world we'd have a weight authority of some nature providing the one and only truth. How about in our world though? And the icing on the cake is that this single data point changes over time. How have you guys solved or managed this conflict?

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  • What are the advantages of storing xml in a relational database?

    - by Chris
    I was poking around the AdventureWorks database today and I noticed that a number of tables (HumanResources.JobCandidate and Sales.Individual for example) have a column which is storing xml data. What I would to know is, what is the advantage of storing basically a database table row's worth of data in another table's column? Doesn't this make it difficult to query off of this information? Or is the assumption that the data won't need to be queried and just needs to be stored?

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  • Lag compensation with networked 2D games

    - by Milo
    I want to make a 2D game that is basically a physics driven sandbox / activity game. There is something I really do not understand though. From research, it seems like updates from the server should only be about every 100ms. I can see how this works for a player since they can just concurrently simulate physics and do lag compensation through interpolation. What I do not understand is how this works for updates from other players. If clients only get notified of player positions every 100ms, I do not see how that works because a lot can happen in 100ms. The player could have changed direction twice or so in that time. I was wondering if anyone would have some insight on this issue. Basically how does this work for shooting and stuff like that? Thanks

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  • How do you plan your asynchronous code?

    - by NullOrEmpty
    I created a library that is a invoker for a web service somewhere else. The library exposes asynchronous methods, since web service calls are a good candidate for that matter. At the beginning everything was just fine, I had methods with easy to understand operations in a CRUD fashion, since the library is a kind of repository. But then business logic started to become complex, and some of the procedures involves the chaining of many of these asynchronous operations, sometimes with different paths depending on the result value, etc.. etc.. Suddenly, everything is very messy, to stop the execution in a break point it is not very helpful, to find out what is going on or where in the process timeline have you stopped become a pain... Development becomes less quick, less agile, and to catch those bugs that happens once in a 1000 times becomes a hell. From the technical point, a repository that exposes asynchronous methods looked like a good idea, because some persistence layers could have delays, and you can use the async approach to do the most of your hardware. But from the functional point of view, things became very complex, and considering those procedures where a dozen of different calls were needed... I don't know the real value of the improvement. After read about TPL for a while, it looked like a good idea for managing tasks, but in the moment you have to combine them and start to reuse existing functionality, things become very messy. I have had a good experience using it for very concrete scenarios, but bad experience using them broadly. How do you work asynchronously? Do you use it always? Or just for long running processes? Thanks.

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  • Tester/Doer pattern: Assume the caller conforms to the pattern or be defensive and repeat the check?

    - by Daniel Hilgarth
    Assume a simple class that implements the Tester/Doer pattern: public class FooCommandHandler : ICommandHandler { public bool CanHandle(object command) { return command is FooCommand; } public void Handle(object command) { var fooCommand = (FooCommand)command; // Do something with fooCommand } } Now, if someone doesn't conform to the pattern and calls Handle without verifying the command via CanHandle, the code in Handle throws an exception. However, depending on the actual implementation of Handle this can be a whole range of different exceptions. The following implementation would check CanHandle again in Handle and throw a descriptive exception: public void Handle(object command) { if(!CanHandle(command)) throw new TesterDoerPatternUsageViolationException("Please call CanHandle first"); // actual implementation of handling the command. } This has the advantage that the exception is very descriptive. It has the disadvantage that CanHandle is called twice for "good" clients. Is there a consensus on which variation should be used?

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