Effective D : best practices and design patterns

Question

A really interesting conference was given about D-Specific Design Patterns and in the D community, some people thought it could be a starting point for a book dealing about effective coding techniques. Others argue that it was too early as not many people have lots of experience, the author(s) of such a book will have some biased/personal appreciation about the notion of effectiveness. SO is a more interactive media (with its limitations). So, waiting for 'Effective D' to come out, it will be great if we could share some (killing) advices/techniques/patterns to make D code look nicer. I think it will be clearer if an answer:

• expose a unique technique
• is essentially a piece of commented code
• (if it is too large) is just a link to the code (public gist...)

Answer 1

I have a few D Tip posts on my blog (1 2 3).

Here's one: Testing With TypeTuple

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When testing a function, it’s usually a good idea to test it with a range of different inputs. To do this, you can easily use a for loop over an array of input values, but what if your input is a type, as it often is with template code?

The D Programming Language allows you to iterate over a TypeTuple, so all you need to do is declare a tuple of all the types you want to test, and iterate over them in the normal way:

import std.typetuple;
alias TypeTuple!(int, long, double) Types;
foreach (T; Types)
    test!T();

You might wonder what this compiles to. After all, the body of the loop varies with T, so the generated code must also vary on each iteration. How does the compiler handle this?

The answer is that the loop is completely unrolled. The code above is literally the same as:

test!int();
test!long();
test!double();

For this reason, you might want to keep an eye on the size of your TypeTuples, to avoid code bloat.