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2
votes
4answers
67 views

Keeping a ratio column that's the division between two other columns

I'm about to build a SQL table where I want to store currency orders. That means that I need to store how much I paid for a certain quantity, and the ratio between both quantities. So for example: ...
0
votes
0answers
17 views

Relying on file hash for data synchronisation across mobile and server

Imagine a client-server app that lets user upload images/documents etc. to server and then lets users who have access, retrieve and view them later on their respective mobile devices. So the flow is ...
10
votes
8answers
775 views

Designs and practices to guard against erroneous null entries from database

One part of my program fetches data from many tables and columns in my database for processing. Some of the columns might be null, but in the current processing context that is an error. This should ...
4
votes
2answers
106 views

Should a RESTful API be able to return files, or just a location

This has been puzzling me for a while. For example, we have a REST API that provides basic content to a system, consuming and producing JSON. At this endpoint it produces a URL to a picture and a ...
2
votes
0answers
31 views

Should my application call statsd directly or should I call statsd based off logs?

I'm planning on incrementing counters in statsd based of various events within my application. I have logging in place for these events. So, from my viewpoint I have two options: Update the ...
0
votes
1answer
44 views

Reusing array with static test data across test classes

I have a Map which takes in an a String key, and an array of custom objects as the value. the map usually contains two entries, and the arrays for both entries never change in terms of data; once they ...
5
votes
5answers
459 views

Advantages of Strategy Pattern

Why is it beneficial to use the strategy pattern if you can just write your code in if/then cases? For example: I have a taxPayer class, and one of its methods calculates the taxes using different ...
1
vote
3answers
166 views

CRUD operations in DDD

I'm designing an application with DDD. I'm moving from flat POCO objects to strong domain models, so my question is: Would I have to call my basic CRUD operations (located in my repository layer) ...
0
votes
1answer
175 views

MVC Best practice mixing Partial View and JavaScript

I searched the internet and really can't find a good answer to this question. Imagine there is a View that contains a simple tab-element. Each tab-content is loaded dynamically (via ajax) when the ...
1
vote
2answers
92 views

Explaining concepts [closed]

How can I explain a concept when I don't know its name or any formal reason for it? The reason I ask is this... A new programmer has entities with a property title in his system. He uses the title to ...
1
vote
0answers
72 views

Algorithm for evaluating line breaks efficiently [closed]

Consider following problem : Given: String input with the length n Font(-metrics) - potentially slow in usage Bounds of an abstract Textview which shall contain the text in a specific manner: e.g ...
1
vote
1answer
89 views

Pattern for passing in a field as a parameter

I'm writing a Rails app which uses ActiveRecord ORM and a Postgres DB. I've got two attributes which are similar but are separate fields in the database. The assignment and saving of these is kinda ...
4
votes
1answer
339 views

How to make sure people call methods in the right order?

Situation I'm designing a database abstraction layer for sql (mysql, sqlite) and mongoDb. The goal is to give the user/developer a library which is able to create queries for different databases. ...
3
votes
4answers
427 views

Where to store average value in db?

I have a restaurant review app which stores reviews in a db, MySql. There's 2 tables. 1 for Restaurant. Another for reviews. To increase the performance, I am considering to store the avg review of ...
7
votes
4answers
334 views

Is there a Haskell idiom for trying several functions and stop as soon as one succeeds?

In Haskell, I can use the type a -> Maybe b to model a function that either returns a value of type b, or returns nothing (it fails). If I have types a1, ..., a(n+1) and functions f1, ..., fn, ...
1
vote
2answers
267 views

Is there a name for this pattern?

A while loop can be written as follows in C# (and many other languages): int someValue; int someTerminatingValue; while ((someValue = GetSomeValue()) != someTerminatingValue) { // Do something ...
1
vote
2answers
242 views

Joshua Bloch Enum Singleton and Third Party APIs

In the book Effective Java he give the best Singleton pattern implementation in his, that is implement by a Enum. I have doubt to how to implement this pattern with a third party API. I'm using an ...
2
votes
2answers
165 views

Does it break SRP to have concerns of data handling and object mapping inside a single class, as part of the DataMapper pattern?

Summary I want to look into separating the concern of "creating a populated object from database", to use inside my application. DataMapper pattern seems to be doing just that for me. DataMapper ...
9
votes
4answers
522 views

Reducing boilerplate in class that implements interfaces through composition

I have a class: A that is a composite of a number of smaller classes, B, Cand D. B, C, and D implement interfaces IB, IC, and ID respectively. Since A supports all the functionality of B, C and D, A ...
1
vote
1answer
52 views

Name pattern for quickly find descendents with SQL (PATH column with [TopId]…[DirectAncestorId].[OwnId]) NO nested sets

I read a long time ago about a pattern/technique for easily querying for all "descendants" of a record (no need to use CONNECT TO, which is not standard and not available with JPA). I remembered the ...
3
votes
4answers
282 views

Function wrappers with no args: bad practice?

My colleague likes to write classes containing methods looking like this: public function doTaskA() { return $this->doTask('A'); } public function doTaskB() { return $this->doTask('B'); ...
1
vote
2answers
611 views

Are the Repository Pattern and Active Record pattern compatible?

Currently I am developing a webapp where I have defined models implementing the Active Record pattern. Each model also is defined by an interface that specifies the Entity properties and makes it easy ...
1
vote
2answers
191 views

Is it a good idea to install more libraries than you need? [closed]

I decided to try Anaconda, it seems that too many large companies are using it. I was amazed by the number of libraries included by default installing: python-2.7.9-2 ... installing: ...
1
vote
1answer
443 views

JSP in Javascript file or multiple AJAX requests

I've been thinking about how I want to load my data for some checkboxes in an AngularJS app. I'm generating multiple checkboxes based on 2 JSON objects that are currenty hard-coded in the a Javascript ...
3
votes
2answers
164 views

Is it OK for an MVC view to request data from other sources than just the model?

I'm working in ASP.NET MVC, but this question is pretty much applicable to any MVC framework (and maybe even others). In a typical MVC application a request arrives at the controller, which then ...
2
votes
1answer
54 views

Queue rescheduling naming convention (Command pattern)

For my project I'm creating a queueing mechanism based on the Command Pattern, which can execute one of a number of jobs. Jobs can add other jobs to the queue or can be added by a human. Most of the ...
7
votes
1answer
356 views

Should I build undo stack in model or its wrapper?

I am building an application (Python/PyQt). The first-order item will be a tree view/model with many helper functions to add new items, move them around in the tree, etc.. Then I will have a main ...
5
votes
3answers
473 views

How to solve the Lava flow anti-pattern?

In this blog post, the author describes an anti-pattern called the "lava flow" In a nutshell, the lava flow anti-pattern happens when many programmers lead the development of an application, each of ...
5
votes
1answer
202 views

Is it poor decision making that using promises for GUI inputs?

So as you know the context: DOM with JavaScript, even though I think it is mostly a language agnostic issue (I know I put both language-agnostic and JavaScript tags, but it's only to let you see ...
0
votes
4answers
296 views

2 methods that are 75% the same? [closed]

I have code that violates the DRY principle and I would like to consolidate 2 methods as much as I can, but the problem I am facing is that they have some differences, I would say they are about 75% ...
0
votes
1answer
142 views

Why use the Singleton pattern over class functions and fields? [duplicate]

I'm going to start by saying that I understand that programming in mostly class functions and variables can be harmful to object-orientation, and that most of the time an instance is preferred. I'll ...
0
votes
3answers
242 views

Check a boolean before setting it in a loop, or just set it

I have a rather tight loop with the following check to see if balance had ever been positive: balance_null = True while (crazy_loop()): ... if 0.0 < balance: balance_null = False ...
2
votes
3answers
1k views

How to implement the repository pattern for an app that will change its database from sql to nosql on in couple of years?

I have been reading a lot about repository implementation. I am confused about which way to implement it for a project I am sure would change its data layer methods because of db migration from MS Sql ...
3
votes
3answers
2k views

Why is it a good practice to keep Javascript code in separate files?

In web development we are commonly used to keep Javascript code in separate files, but sometimes we need this Javascript code to manipulate server side data locally. For example, making an Ajax Call ...
4
votes
2answers
104 views

Is it a good idea to have a database row that represents an unknown value within a system [closed]

We have two systems, System A imports a list of sports events from system B, it only wants to import the events we will be providing live data for, the filter used to hide events that we are not ...
2
votes
1answer
101 views

Combining Patterns: Fluent Builder and Null Object Pattern

I am currently wrestling around with some GUI code where I have a table whose rows correspond to some object, let's say a Person object. When the table initializes, it fills the table with the Person ...
4
votes
2answers
857 views

TDD with repository pattern

In my new project, I decided to try with TDD. And in very beginning I encountered a problem. First thing that I want to do in my application is to give ability to read data from data source. For this ...
0
votes
1answer
1k views

Design Pattern for Cron/Schedule in MongoDB

I am looking for a good pattern to handle cron-type data in a MongoDB collection (or collections). I have been peeking at the O'Reilly book MongoDB Applied Design Patterns and poking around the ...
2
votes
1answer
240 views

In a Table Data Gateway, where do I put queries that use joins

The book Pattern of Enterprise Application Architecture has the following description over the Table Data Gateway pattern: “A Table Data Gateway holds all the SQL for accessing a single table or ...
0
votes
1answer
85 views

Does a create() method exist as part of a pattern? [closed]

Is there something special(i.e. a design pattern being related) to a method named create()? Background The case is, I often make some instances of objects (of the same class/prototype). These ...
4
votes
3answers
916 views

DDD, modularizing the application and domain layers without breaking the DIP

Quoting DDD theory: The application layer is thin in terms of domain logic - it merely coordinates the domain layer objects to perform the actual work. When it comes to modularization, and ...
0
votes
1answer
76 views

Control (avoid) changing fields with side-effects

I have been thinking about a design problem and possible solutions in my own. I am pretty sure I am not the first one to have noticed it, but I cannot google for it since I do not know the standard ...
1
vote
0answers
103 views

Decreasing MongoDB Load

I have some stream workers. They are listening to twitter stream and save into mongodb. I need to aggregate saved tweets for intermediate analyze result. I have analyzer workers. They are periodically ...
1
vote
1answer
120 views

Obsessed with filling hashmaps instead of using else if cascades or switch statements [duplicate]

Whenever I feel like choosing from a list of implementations I always prefer to fill a map first and then call whatever I need based on a parameter, instead of using switch or else if statements. ...
13
votes
5answers
6k views

What is the best way to initialize a child's reference to its parent?

I'm developing an object model that has lots of different parent/child classes. Each child object has a reference to its parent object. I can think of (and have tried) several ways to initialize the ...
2
votes
0answers
180 views

Callback pattern handling exceptions - Best practices in .NET 3.5

I am looking to implement the callback pattern with error handling such that error is caught and pass to the callback code with the response. Since I am using .NET 3.5, I cant use Task (TAP) pattern ...
0
votes
1answer
100 views

How to save entities relations using unit of work pattern

I use Unit of work pattern to commit all new, dirty, deleted entities to the DB (using a db_mapper). Example of entities are: Student and Class So Student->registerDirty() will add this entity to ...
-1
votes
1answer
138 views

Best solution for future maintenance of a website with hardcoded ids, custom CMS using bad database design [duplicate]

Recently I was put into a position of a tech-lead on a very interesting project that I have been partially working for two years. This project carries a lot of legacy stuff with it even though we try ...
4
votes
2answers
124 views

Factors for choosing between using a wrapper library or issuing command line process from my web application

I have a Java web application that makes use of certain libraries for example: Ghost Script for converting PDFs to TIFFs and Tesseract for OCR. There are java wrappers for both of these: Ghost4J and ...
0
votes
2answers
157 views

When should you create/destroy underlying object in a class that wraps it

(note: I used Java to make it easer to explain my question, but the actual language is irrelevant for this dilemma) TL; DR: I have a wrapper around some underlying class. At which point should I ...