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Compiling enterprise

Ivan Koshelev blog on software development

Roslyn beyond 'Hello world' 02 Visual Studio extension for refactoring [2017 August 01] .NET, C#, Roslyn, Visual Studio, Refactoring

From the point of view of developer using it (we will call them 'user-dev'), Refactorings in Roslyn are additional commands that pop-up in Visual Studio when they click certain pieces of code. From our point of view, Refactorings are classes inheriting from CodeRefactoringProvider, which get a chance to examine current syntax graph every time user-dev clicks something in it and determine, if they should offer any transformations of that graph based on its state and what was clicked.

We will be building a Refactoring which allows our user-dev to regenerate a given classes public constructor by adding to it any missing assignment of members that match a certain pattern and are not yet assigned during construction. Specifically, this is the refactoring we use at work to regenerate dependency injected constructors.

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Debugging JavaScript 01 Advanced forensic techniques [2017 July 29] JavaScript, Debug, Forensics, Proxy

JavaScript is among the most open-source friendly languages. Thus, when faced with a question “why doesn’t it call this function?” or “What changes this property?”, most of the time we have the code of 3rd-party libraries ready and available for us to dive into for debug. Still, sometimes you only have the minified version of a library, or a normal version so big and complicated - you give up after pressing “step into method” over 30 times. You need to track the exact place where one of your objects properties is used.

Solution? Use Chrome and the most awesome feature of ES6 – Proxies! Your users are locked into IE 8 and no ES6? What’s wrong with your organization? Ok, but you as a developer, surely can use Chrome, just for this debug session? Proxies are supported by all modern browser releases for at least a year , and current versions of Node.

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Roslyn beyond 'Hello world' 01 Important concepts and development setup [2017 July 24] .NET, C#, Roslyn, Visual Studio

.NET Compiler Platform, better known as Roslyn, has been one of the best things that happened to C#. In short, it is a compiler made with IDE integration and extensibility in mind. It provides us with hooks to add our own analysis and transformations to the process of compilation. Why is that important? If there was ever a coding rule specific to just one of your projects, that you had to inforce with lots of discipline and diligence, but would rather rely on the compiler for it, or a routine operation you could easily automate if only you could write an IDE extension – Roslyn will make this a reality. It allows you to write code, C# code in my case, that will run as a Visual Studio extension, analyze the code other devs are working on and help them modify it.

Unfortunately, despite initially releasing with Visual Studio 2015, there is still lack of tutorials teaching how to do things beyond ‘Hello world’. For serious development, the best way to learn is to read official documentation wiki and study other prjects available on github - quite a lot of overhead, even if Roslyn is worth it. This series will provide with a more streamlined roadmap - enough knowledge to do useful things and guidelines for farther research. Through the series we will build a refactoring extension for Visual Studio and a simplistic analyzer dll to include into a project. Both small enough to comprehend in an hour, yet performing useful work, solving a task the likes of which you may expect to want to automate yourself in your project. As well as techncial infromation, which can be quite overwhelming at first site, I will try to give hints on the general flow of Rolsyn development: how to decide where to start, how to deal with roadblocks, how to concentrate on important things first.

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Technical interviewer guide [2017 July 09] Technical interviewing

This article sums up my experience conducting 100+ technical interviews for a big software development outsourcer\outstuffer. It is aimed at interviewers with the goal of helping them prepare for the process and handle typical issues that come up as well as responsibility to both their company and the person being interviewed.

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Expression trees and advanced queries in C# 03 Expression Tree modification [2017 May 28] .NET, C#, IQueryable, Expression Tree, Expression Visitor

In part 1 we learned that you can swap parts of an Expression Tree to another compatible (i.e. with a matching return type) expression. Swapping is, in fact, the easiest thing to do - with a bit more work we can construct a serializable representation of almost any bit of C# code. This opens great avenues for Domain Driven Development and introducing hot-swappable, dynamic, yet safe parts of logic to your application.

One of the best examples of the power we get is shown by introducing a reusable expression function with LINQKit.

internal static class AddressSubqueries
{
internal static Expression<Func<string, string, string>> FormatCityAndProvince =
    (city, province) => "The glorious city of " + city 
                            + " of the wonderful province of " + province;
}
     
//used like this:
public IQueryable<string> GetStandardAddressDescription(int addressId)
{
    return DataContext
                .Addresses.AsExpandable() // this hooks in LINQKit 
                .Where(x => x.AddressId == addressId)
                .Join(
                    DataContext.StateProvinces,
                    adr => adr.StateProvinceId,
                    prov => prov.StateProvinceId,
                    (adr, prov) => AddressSubqueries.
                                        FormatCityAndProvince // <==
                                            .Invoke(adr.City, prov.Name))
                .FirstOrDefault();
}
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I'm passionate for anything that can be programed and automated to make life better for all of us.

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