Re: IDENTIFIERS in Upper Case

[Jerry Petrey <gdp@mlb.cca.rockwell.com>]

Matthew Heaney wrote:
> 
> In Guidelines for Enterprise-Wide GUI Design, authors Susan Weinschenk and
> Sarah C. Yeo state that "Sentances in all capital letters are 20 percent
> more difficult to read than sentences with upper- and lower-case letters.
> Avoid using all caps for large blocks of text." [p. 101]  They later state,
> when discussing online help, that one should "Never use all caps, except
> for acronyms and initializations.  Words in all caps are harder to read."
> [p. 144]
> 
> In Usability Engineering, author Jakob Nielsen states that "On alphanumeric
> terminals, UPPERCASE TEXT CASE CAN ALSO BE USED TO GET THE USERS'
> ATTENTION, but upper case should be used sparingly as it is about 10%
> slower to read than mixed-case text." [p. 118-9]
> 
> In Principles and Guidelines in Software User Interface Design, author
> Deborah J. Mayhew states "Avoid heavy use of all-uppercase letters.  Text
> in all uppercase is more difficult to read than text in mixed case.  Tullis
> (1988) reviews literature suggesting that people read mixed case text about
> 13% faster than uppercase.  This is because lowercase letters look more
> different from one another than do uppercase letters, making it easier to
> determine a word in part by its overall shape." [p. 469]
> 

The problem with most of the studies is that they address the effect of
case in normal human reading - we don't read programs in the same way
we read a novel. IMO, programmers can adapt quite well to most any
reasonable case style.  The key thing is separating identifers and
key words to bring out the structure (I still find all uppercase
identifiers
work well for that but the mixed case style seems to be more preferred
today, so I adapt).  There are many other factors that have a much
greater 
influence on readability of programs, e.g. use of white space, a good 
indentation scheme, good choices of names, etc.  Most important is some 
reasonable guidelines within an organization and a consistent use of 
those guidelines.  Expecting the entire Ada (or any other language) 
community to adhere to the same guidelines would be nice but not
realistic
 - conformity within an organization is probably the best we can
achieve.

Jerry



-- 
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== Jerry Petrey                                                    ==
== Consultant Software Engineer - Member Team Ada and Team Forth   ==
==            Rockwell Collins Commercial Avionics Group           ==
==            Melbourne, FL   email: gdp@mlb.cca.rockwell.com      ==
=====================================================================