MAPL Coding standards

Entity names

Procedure names

Procedure names should generally be verbs and in camel_case. E.g., get_next_token().

Variable names

The importance of a variable name depends on its scope. The names of module variables being the most crucial, and local variables within a procedure being the least crucial. Dummy argument names are intermediate.

Abbreviations should be avoided unless exceptionally clear and consistently applied. The common exception is a prefix to indicate "number of", e.g., n_bins is an acceptable abbreviation of number_of_bins. While this convention can lead to longish names, the Fortran ASSOCIATE construct allows aliases to be used within formulae:

associate (G =>  universal_gravitational_constant)
    f = G * m1 * m2 / r**2
end associate

Multiword variable names should use snake_case.

A variable name should be a noun, and generally be singular. The exception is for containers (arrays, lists, vectors) where plural nouns are more appropriate. For example

real :: density_of_air
integer, allocatable :: items(:)

Note that this rule can be subtle. E.g. we use 3D arrays to represent fields, but usually refer to these fields in the singular:

type(ESMF_Field) :: humidity

Derived type names

The names of derived types should be singular nouns and generally be written in CamelCase. E.g,: IdentityRegridder.

Module names

Module names should generally have a package-indicator prefix and not have a suffix. E.g., MAPL_HistoryGridComp. The major exception to this is for the top module for a package which usually just consists of a set of USE statements. These module names should just be the package name. E.g., MAPL.

Multiword module names should use CamelCase.

In the common case where a module declares a single public derived type, the module name should correspond to the name of that derived type. Note: module names have a package prefix but derived type names do not. E.g., the module. E.g., the module pf_DirectoryService provides the derived type DirectoryService.

File names

Ideally each source file will will consist of a single program unit: subroutine, function, module, or program. The name of the file should correspond to the contained program unit. If the contained program unit is a module, the file name should not include the package-indicator prefix.

The file-type suffix should generally be .F90 indicating the use of free format and allowing the use of FPP/CPP macros.

For example, the file containing the module MAPL_HistoryGridComp should be called HistoryGridComp.F90