Skip to content

BHoM's coding style and conventions

General C# conventions

Our coding style generally follows the Microsoft guidelines on C#.

However, to attain a higher level of clarity and transparency, BHoM code also adheres to additional customised rules and style guidelines.

Additional conventions

BHoM code also adheres to customised rules and style guidelines. These are in place for several reasons, mainly:

  • to make easier to read and contribute to the codebase;
  • to ensure the functionality can be correctly exposed to the UIs;
  • to organise functionality and classes in a tidy, easy-to-find manner.

Access modifiers

Access modifiers specify the accessibility level of type and type members. They denote whether a type or member can be used by other code in the same assembly, and in other assemblies.

  • In line with BHoM's focus on clarity and transparency, we generally use the public access modifier, which allows a type or member to be accessed by any other code in the same assembly or other assembly that reference it.
  • When absolutely necessary, we use the private access modifier to limit the access of a type or member to only code in the same class.
  • Although C# provides many access modifiers, we limit our use to the two mentioned above.

Filenames, objects and methods

  • A .cs file can contain only 1 (one) class, and there is no concept as a Helper or Utils class.
  • For oM objects the name of the .cs file is the Name (excluding the namespace) of the Object (class), e.g. the Line class is in the Line.cs file.
  • For engine methods, a file can only contain methods whose name start or end with the name of their file file, e.g. Flip(Line line) and Flip(Arc arc) are in the same file Flip.cs, and FilterPanels and FilterOpenings can both reside inside a Filter.cs file.

Folders and namespaces

Namespaces and the folder structure that contains the .cs files have a close relationship. To define the correct folder structure helps keeping the relationship with the namespaces. This, in turn enables additional functionalities, such as deriving the web address of the source code of a method.

For a Class, an Attribute, an Enum, and an Interface, the folder structure respects the following rules:

  • If a file is in a sub folder, the namespace of the entity must follow: if Bar is in a sub folder Elements, its namespace must suffix the Elements word BH.oM.Structure.Elements.

  • An Enum must be in a separate folder Enums. Although, the namespace remains unchanged, and does not follow - i.e. Enums is appended as suffix. For example BarFEAType is in the sub folder Elements, and it is an enum. Its namespace respects A., so it contains the Elements word, but does not contain the Enum word: BH.oM.Structure.Elements. At the same time, since it is an Enum it is in an Enums folder.

  • The same rule as B. applies to:

  • Attribute => Attributes
  • Interface => Interfaces

Enum ordering

The order an Enum is written is the order in which it is displayed in the UI dropdown options. This order is therefore important to the UX of using the Enum within a workflow. The order should therefore follow one of the following conventions. There may be occasions when an Enum order does not follow the conventions below. These occasions should be clearly documented with the reasons why a different convention has been followed.


The order of the Enum should be alphabetical (following British-English spelling conventions) in ascending order (i.e. A-z).

Caveat for Undefined

If your Enum option has an Undefined option to denote a default unset option, then this should go as the first option at the top of the Enum.

For an example of an Enum following this convention, see the Environment Panel Type Enum.


The order of the Enum can be in a logical order instead where this makes more sense than alphabetical. An example of such an Enum might be one that records the size of an object. In this case, the options might be:


This order for the Enum makes logical sense and provides a good UX where users will have context from the name of the Enum that the order might be different to alphabetical (e.g. the name might be UnitSize).

Yoda condition

For conditional statements, the variable expression should be placed in front of the constant expression. When this order is reversed, it is referred to as a "Yoda condition". For readability, we avoid using Yoda conditions in our code base. An example of both is given below.

string str = "hello world" 

if (str == "BHoM") { /* … */} //most common convention - preferred for BHoM development

else if ("BHoM" == str) {/* … */} //Yoda style, as the constant "BHoM" precedes the string variable