nim-wiki/NEP-1.md

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Nimrod Enhancement Proposal #1 - Standard Library Style Guide

Abstract

Although Nimrod, through its flexible AST and case-sensitivity settings, supports a variety of code and formatting styles, it is nevertheless beneficial that certain community efforts, such as the standard library, should follow a consistant set of style guidelines when suitable. This enhancement proposal aims to list a series of guidelines that the standard library should follow. Note that these are guidelines only. The nature of Nimrod being as flexible as it is, there will be parts of this style guide that don't make sense in certain contexts. Furthermore, just as Python's style guide changes over time, this style guide will too.

Style Guidelines

General

  • Type identifiers should be in CamelCase. All identifiers should be in pascalCase.

    const
      aConstant = 42
    
    var
      aVariable = "Meep"
    
    type
      FooBar = object
    
  • Members of enums should have an identifying prefix, such as an abbreviation of the enum's name.

    type PathComponent = enum
      pcDir
      pcLinkToDir
      pcFile
      pcLinkToFile
    
  • Lines should be no longer than 80 characters

  • 2 spaces should be used for indentation. Although one can use tabstops for indentation through use of template filters, this considered an unneccessary hack.

  • The 'return' statement should only be used when it's control-flow properties are required. Use a procedures implicit 'result' variable instead. Using the implicit result variables allows both the Nimrod compiler and its various backends to perform special optimizations

  • Use the 'let' statement (not the var statement) when declarding variables that do not change within their scope. Using the let statement ensures that variables remain immutable, and gives those who read the code a better idea of the code's purpose.

  • Any tuple type declarations that are longer than one line should use the regular object type layout instead. This enhances the readability of the tuple declaration by splitting its members information across multiple lines.

    type
      ShortTuple = tuple[a: int, b: string]
    
      ReallyLongTuple = tuple
        wordyTupleMemberOne: string
        wordyTupleMemberTwo: int
        wordyTupleMemberThree: double
    
  • Similarly, any procedure type declarations that are longer than one line should be formatted in the style of a regular type.

    type
      EventCallback = proc (
        timeRecieved: TTime
        errorCode: int
        event: Event
      )
    
  • Multi-line procedure declarations/argument lists should continue on the same column as the preceding brace. This style is different from that of procedure type declarations in order to prevent confusion between the heading of a procedure and its body.

    proc lotsOfArguments(argOne: string, argTwo: int, argThree:float
                         argFour: proc(), argFive:bool): int
    
  • Use of extra whitespace for alignment is generally discouraged. This is not neccessarily because such a style is bad, but because of the varying support editors have for auto aligning blocks of code, and the fact that manually aligning and re-aligning parts of code can be quite time consuming.