Skip to main content

Welcome to Pipe's Coding Clues

Hi, I'm Felipe Martínez (aka Pipe) from Spain. I've been coding for 5 or 6 years, my main language is C# but I'm also comfortable in C++, JS, Java and Python. In this blog I hope to tell you about my experiences while coding, as well as give you some tips!


Popular posts from this blog

ConditionalWeakTable, what does it do?

C#'s ConditionalWeakTable, what does it do?C# has many lesser known features, some more useful than others, and one of them is the ConditionalWeakTable<TKey, TValue> (keep in mind that TKey and TValue must be reference types).
You can think of this type as a dictionary where the keys are weakly referenced, meaning that they won’t count when the GC checks if the object has to be collected. Additionally, when the keys do eventually get collected by the GC, that entry will get removed from the dictionary. This means that you can attach arbitrary objects to any object, allowing you to do something like this:publicstaticclassExtensions{privatestatic ConditionalWeakTable<object,dynamic> Table =newConditionalWeakTable<object,dynamic>();publicstaticdynamicData(thisobject obj){if(!Table.TryGetValue(obj,outvar dyn)) Table.Add(obj, dyn =newExpandoObject());return dyn;}}...var myObject ="hello"; myObject.Data().Foo ="bar"; Assert.AreEqual(myO…

C# to JS: LINQ Expressions and ExpressionVisitor

How to translate (some) C# to JavaScriptIf you’ve ever used something like EF Core you may have noticed that methods like LINQ’s Where take an Expression<Func<...>> as the first argument, instead of simply a Func<...>:
Expressions were introduced in .NET 3.5 along with the rest of LINQ and they represent the code tree that a lambda is composed of. For example, if you had a lambda like () => a + b, this is how the resulting expression tree would look like:
.NET 4.0 later introduced ExpressionVisitor, which lets you traverse the expression tree. Take this visitor for example:publicclassConsolePrinterVisitor: ExpressionVisitor {//This is just a helper method to get the Expression, normally you would already have it//so you'd just do ConsolePrinterVisitor.Visit(expression)publicvoidWriteLambda(Expression<Func<object>> expression){this.Visit(expression);}protectedoverride Expression VisitBinary(BinaryExpression node){ Console.Write("("…

Building LINQ Expressions: How to run dynamic code at runtime (part 1)

How to run dynamic code at runtime (part 1)In my previous post I talked about how to read LINQ expressions using an ExpressionVisitor, however reading isn’t the only thing you can do with expressions: you can build them at runtime!If you’ve ever used reflection you’re probably aware that you shouldn’t use them in performance-critical situations as they’re one of the slowest parts of .NET, but what if you desperately need to use it?Enter the world of expression-building. Before I show you how anything works, I want you to compare speeds: RawAccess: 00:00:00.0000344 b*1,0 (3,44E-06ms per iteration) ReflectionNoCache: 00:00:00.0018118 b*52,7 (0,00018118ms per iteration) ReflectionWithCache: 00:00:00.0009518 b*27,7 (9,518E-05ms per iteration) ExpressionNoCache: 00:00:00.9333534 b*27132,4 (0,09333534ms per iteration) ExpressionWithCache: 00:00:00.0000424 b*1,2 (4,24E-06ms per iteration) Benchmark ran with .NET Core 2.2 on an AMD Ryzen 2400G @ 3.85Ghz and Windows 10.As you can …