[LLVMdev] RFC: variable names

[Philip Reames]

On 10/13/2014 03:04 PM, Nick Kledzik wrote:
> I’d like to discuss revising the LLVM coding conventions to change the 
> naming of variables to start with a lowercase letter.  This should not 
> be a discussion on the pain of such a transition, or how to get from 
> here to there, but rather, if there is a better place to be.
+1, leaving aside all practicalities of migration
>
> My arguments for the change are:
>
> 1. No other popular C++ coding style uses capitalized variable names. 
>  For instance here are other popular C++ conventions that use camelCase:
>
> http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml
> http://www.c-xx.com/ccc/ccc.php
> http://geosoft.no/development/cppstyle.html
>
> And, of course, the all-lower-case conventions (e.g. C++ ARM) don’t 
> capitalize variable names.  In addition, all the common C derived 
> languages don’t use capitalized variable names (e.g. Java, C#, 
> Objective-C).
>
>
> 2. Ambiguity.  Capitalizing type names is common across most C++ 
> conventions.  But in LLVM variables are also capitalized which 
> conflates types and variables.  Starting variable names with a 
> lowercase letter disambiguates variables from types. For instance, the 
> following are ambiguous using LLVM’s conventions:
>
> Xxx Yyy(Zzz);  // function prototype or local object construction?
> Aaa(Bbb);  // function call or cast?
>
>
> 3. Allows name re-use. Since types and variables are both nouns, using 
> different capitalization allows you to use the same simple name for 
> types and variables, for instance:
>
> Stream  stream;
>
>
> 4. Dubious history.  Years ago the LLVM coding convention did not 
> specify if variables were capitalized or not.  Different contributors 
> used different styles.  Then in an effort to make the style more 
> uniform, someone flipped a coin and updated the convention doc to say 
> variables should be capitalized.  I never saw any on-list discussion 
> about this.
>
>
> 5. Momentum only.  When I’ve talked with various contributors 
> privately, I have found no one who says they likes capitalized 
> variables.  It seems like everyone thinks the conventions are carved 
> in stone...
>
>
> My proposal is that we modify the LLVM Coding Conventions to have 
> variable names start with a lowercase letter.
>
> Index: CodingStandards.rst
> ===================================================================
> --- CodingStandards.rst(revision 219065)
> +++ CodingStandards.rst(working copy)
> @@ -1073,8 +1073,8 @@
>    nouns and start with an upper-case letter (e.g. ``TextFileReader``).
>
>  * **Variable names** should be nouns (as they represent state). The 
> name should
> -  be camel case, and start with an upper case letter (e.g. ``Leader`` or
> - ``Boats``).
> +  be camel case, and start with a lower case letter (e.g. ``leader`` or
> + ``boats``).
>
>  * **Function names** should be verb phrases (as they represent 
> actions), and
>    command-like function should be imperative.  The name should be 
> camel case,
>
>
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