Tips & Tricks

There are some additional features and tools you can put to use, to make the literate programming experience even better. Let's look at few of them.

Including Formulas

LiterateCS uses the Markdig parser to generate HTML from markdown. Markdig supports mathematical formulas inside the markdown. Formulas are rendered by the MathJax Javascript library. The library is loaded only if the UseMath property is specified in the front matter.

To include formulas in your comments write them in the TeX format. For example, the quadratic equation is defined like this:

$x = { -b \pm \sqrt{b^2 - 4ac} \over 2a }$

and rendered like this:

x = { -b \pm \sqrt{b^2 - 4ac} \over 2a }.

MathJax library is loaded from a CDN (Content Delivery Network) and not included in the auxiliary files coming with the theme. The reason for this is the big size of the library, and the fact that it is not always needed. Enabling the feature will increase page loading times, but the penalty is not that big. When mathematics support is required, this feature is invaluable.

Including Diagrams

Another feature that makes your documentation more lively and readable is the support for diagrams. Obviously you can include PNG/GIF/JPG images in your markdown using the ! syntax. This is a standard markdown feature which works as expected.

However, if you just want to present diagrams that illustrate the program logic, drawing those as images can be quite laborious. You need to pick up a paint or drawing program, export the pictures to files and include the files in your project. Maintaining the pictures also quickly becomes a chore.

For this purpose, it is easier to define your diagram directly inside the markdown and let the mermaid library generate the images. Mermaid support flowcharts, sequence diagrams, and Gant diagrams. On of these usually fills the need when a clarifying picture is called for.

Below is an example diagram that is generated from the following definition:

   ```mermaid
   graph LR
       A[Hard edge] -->|Link text| B(Round edge)
       B --> C{Decision}
       C -->|One| D[Result one]
       C -->|Two| E[Result two] 
   ```
graph LR A[Hard edge] -->|Link text| B(Round edge) B --> C{Decision} C -->|One| D[Result one] C -->|Two| E[Result two]

Diagram support is not enabled by default. To enable it, set the UseDiagrams property to true in the front matter. You can also change the visual appearance of the diagrams with the DiagramStyle property.

Editing Markdown in Visual Studio

Literate programming using Visual Studio can be made more pleasant by installing couple of extensions. Visual Studio Marketplace offers multiple choices if you are looking for an extension that provides syntax highlighting and support for markdown files. I am using Markdown Editor for this purpose.

There is far more scarce supply of extensions that help editing markdown inside C# comments, though. The only option I have found is MarkdownComments by Julien Duminil. It has a few very handy features, such as showing headings in bigger font and previewing the pictures. However, it has a couple of issues which cause the latest version not working correctly with C# files (only with C++). I have submitted a pull request to fix those issues, but it has not yet been merged to the master branch.

If you feel experimental and want to try it out, I suggest taking my branch from GitHub and building the extension yourself. Installing it is just a matter of double-clicking the produced installer. You can uninstall it easily from Visual Studio, if you don't like it.

The last extension I would recommend is the Visual Studio Spell Checker. Spell checking is of course completely optional, and the value of correct spelling is subjective. Nevertheless, I find it very helpful when writing documentation that somebody or something is checking what I type. When writing code the compiler is doing that job. With documentation there is nothing helping you by default. That is why I think a spell checker is a precious tool - also within Visual Studio.

Running LiterateCS inside the Build

Since LiterateCS is a command line tool, it can be integrated to the build process with little effort. You can add it as the post-build step in Visual Studio solution, or incorporate it in your continuous integration scripts. However you are doing it, just bear in mind that LiterateCS will actually build your projects twice, because setting up Roslyn in .NET Core is somewhat complicated task currently. So, if your code base is big, the tool will take some time. Therefore, I don't recommend running it automatically within every build. Better launch it separately when you want to review your documentation.

Also, I don't suggest that the errors coming from the tool should be used as the cause of failing a build. There are cases when Roslyn reports errors, even though the project compiles correctly in Visual Studio.

If you don't want to see the compilation errors at all, or if they hinder your build process, you can get rid of them by redirecting STDERR to null. In command prompt, it is done like this:

literatecs <options> 2> nul

In PowerShell the same thing is quite a bit more complicated. It is not enough to suppress the error messages, you also need to make sure that PowerShell does not terminate LiterateCS immediately when it outputs to STDERR. So, we need to temporarily set $ErrorActionPreference variable to ignore the errors.

& {
    $ErrorActionPreference = "SilentlyContinue"
    & LiterateCS <options>
}

LiterateCS will indicate with its return code if it succeeded or not. To check if the document generation worked in PowerShell, you should inspect the $LASTEXITCODE variable.

if ($LASTEXITCODE -eq 0)
{
    # Document generation succeeded.
}