Path: utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!umd5!rutgers!clyde!cbosgd!gwspc!cbcsta!n8emr!oink!jep
From: jep@oink.UUCP (James E. Prior)
Newsgroups: comp.lang.c
Subject: Re: == vs =
Message-ID: <214@oink.UUCP>
Date: 17 Jan 88 17:06:26 GMT
References: <626@PT.CS.CMU.EDU>
Reply-To: jep@oink.UUCP (James E. Prior)
Organization: Random Prime Research Institute  Columbus, Ohio
Lines: 41

In article <626@PT.CS.CMU.EDU> edw@IUS1.CS.CMU.EDU (Eddie Wyatt) writes:
>I do not propose changing
>the C language nor do I say the compiler should flag this contruct
>(it is perfectly valid construct for the language which I
>use myself).  The language D should redefine assignment to
>:= then hopefully this type of bug will go away. (ie. we should
>learn from our mistakes)

>Eddie Wyatt 				e-mail: edw@ius1.cs.cmu.edu

I appreciate the choices that the authors of C made for = and ==.
They chose based on which would save them typing.  The single '=' was 
chosen for assignment because assignment is used more than comparison.  
Comparison got the double '=' pretty much by default.  

I have no problem distinguishing between = and ==, and don't want to
change them at all.  Nonetheless I would find changing == much less 
obnoxious than changing =.  Like the authors of C, I find it most 
important to preserve a single character operator for assignment.  
I liken == to the very wide symbol used in mathematics a couple
hundred years ago to state equality.  I do realize that use of
== in C for comparison is interragative as opposed to the use of the
very wide symbol in ancient math being imperative.  Changing == to 
something else like :: would make sense.

I find := for assignment to be quite obnoxious.  It's the worst choice
I've ever seen.  I understand the pressure from other languages that 
use it, but it is two characters long, misleading, and hideous to look
at.  In math : is often used for comparison, as in ratios.  Using : in 
:= for assignment misleads me to think of comparison instead of 
assignment.  := isn't even pleasing to look at.  It's downright ugly.  

Cyber folklore around the office has it that := originated in Europe 
as something that looked similar to <=.  Their left pointing arrow wasn't
a <, it was a legitimate left arrow that matched up with an =.  Their 
left pointing arrow symbol was intuitive and showed the flow of data 
from the expression on the right side to the variable on the left.  
When their <= crossed the Atlantic it had to be converted to ASCII.  
We didn't have the same clean arrow symbol so it somehow got converted 
to :.  We've been suffering with := ever since from a poor translation.

I do appreciate the distinction you make between the C language as 
opposed to 'D'.
-- 
Jim Prior    jep@oink.UUCP    {ihnp4|cbosgd}!n8emr!oink!jep
Pseudo-programmers use pseudo-code to write pseudo-programs on pseudo-machines!