Re: I Don't Make Mistakes. I Use C

From	Bernd Paysan <bernd.paysan@gmx.de>
Newsgroups	comp.lang.forth
Subject	Re: I Don't Make Mistakes. I Use C
Date	2012-10-27 19:14 +0200
Organization	1&1 Internet AG
Message-ID	<1356869.8RI3Fb9bJL@sunwukong.fritz.box> (permalink)
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visualforth@rocketmail.com wrote:

> On Saturday, October 27, 2012 1:04:20 AM UTC-4, Paul Rubin wrote:
>> "Elizabeth D. Rather" <forth.com> writes:
>> > More to the point, is it something a compiler can detect?
> It absolutely is, some of the time. E.g., person A was told to write a
> module with interface X, and person B was told to write a client for
> A's module, using interface Y, where X is not equal to Y. Lots of
> mismatches of this sort are routinely caught by compilers.
> 
> Using Forth you would get the error message
> 
> Y
> ^
> Error(-13): Y is undefined
> X
> ^
> Error(-13): X is undefined
> 
> or something like that. Isn't that enough?

What he presumable means is that you say "the function will see a string 
on the stack, specified by address and length, and person A writes

: type ( len addr -- ) { addr } 0 ?DO addr i + c@ emit LOOP ;

and person B assumes that of course it's ( addr len -- ) and tries

s" foo" type

which then crashes, instead of printing a type error.

The reason why this doesn't matter much in Forth is that Forth 
programmers acutally test their functions.  They don't just compile and 
are happy when that is done without error messages - it usually is, the 
real work starts after it compiles.

When I interface with external libraries or such, I generate my bindings 
with Swig (automatic), and then I start testing the words I use.  And 
then it goes "boom", "boom", "boom", because these C functions are 
mostly untested.  They compiled, yes.  Without error.  That's it.

Examples I had seen with the simple OpenGL terminal (using GL Shader 
Language) of Gforth for Android:

* The glUniformf variants (passing a float directly instead of a pointer 
as with glUniformfv) doesn't work with AMD/ATI's driver, and it doesn't 
report an error.  The value passed is simply always 0.

* The function mix(color1, color2, alpha), which should translate to 
color1*alpha+color2*(1-alpha) doesn't on my Defy+, there it maps to 
color1*alpha+color2.  WTF?  Didn't they test it?

* The array index in the GLSL works for static indices on Huawei's cheap 
phone, but not for variable indices (variables as index is the only 
meaningful reason to use an array).  Neither does this print an error 
message.  It obviously was simply untested - the test case apparently 
only had a static index.  Maybe the Khronos group should publish a 
comprehensive test suit for their standards.

IMHO it's a good thing that in Forth the compiler tells you almost 
nothing about the quality of your program.  Only simple typos are 
reported.  This means you *absolutely must* test it.  Because otherwise, 
it will definitely not work.  And there, Forth provides a lot of means 
to test without much effort.  If the compiler lulls you in false 
confidence about the quality of the program, you forget testing.  You 
still have to do it.  The type errors are minor compared to the logical 
errors.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://bernd-paysan.de/

Thread

I Don’t Make Mistakes. I Use C visualforth@rocketmail.com - 2012-10-23 16:09 -0700
  Re: I Don’t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-23 16:43 -0700
  Re: I Don’t Make Mistakes. I Use C jacko <jackokring@gmail.com> - 2012-10-23 16:50 -0700
    Re: I Don’t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-23 18:58 -0700
      Re: I Don’t Make Mistakes. I Use C jacko <jackokring@gmail.com> - 2012-10-24 15:12 -0700
  Re: I Don’t Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-23 14:02 -1000
    Re: I Don’t Make Mistakes. I Use C Bernd Paysan <bernd.paysan@gmx.de> - 2012-10-24 02:51 +0200
      Re: I Don’t Make Mistakes. I Use C Mark Wills <forthfreak@gmail.com> - 2012-10-24 04:23 -0700
    Re: I Don’t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-23 19:20 -0700
    Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-24 05:04 -0500
      Re: I Don?t Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-24 08:04 -1000
        Re: I Don?t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-24 13:11 -0700
          Re: I Don?t Make Mistakes. I Use C Pavel Klinkovsky <pavel.klinkovsky@gmail.com> - 2012-10-24 13:21 -0700
          Re: I Don?t Make Mistakes. I Use C Fritz Wuehler <fritz@spamexpire-201210.rodent.frell.theremailer.net> - 2012-10-25 20:00 +0200
            Re: I Don?t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-25 11:30 -0700
              Re: I Don?t Make Mistakes. I Use C Anonymous <nobody@remailer.paranoici.org> - 2012-10-26 09:00 +0000
                Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-26 05:01 -0500
                Re: I Don?t Make Mistakes. I Use C Brad Eckert <hwfwguy@gmail.com> - 2012-10-26 08:46 -0700
            Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-25 23:05 -0500
              Re: I Don?t Make Mistakes. I Use C Anonymous <nobody@remailer.paranoici.org> - 2012-10-28 15:35 +0000
                Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-28 12:06 -0500
                Re: I Don?t Make Mistakes. I Use C Bernd Paysan <bernd.paysan@gmx.de> - 2012-10-28 21:38 +0100
                Re: I Don?t Make Mistakes. I Use C jacko <jackokring@gmail.com> - 2012-10-28 16:34 -0700
                Re: I Don?t Make Mistakes. I Use C Anonymous <nobody@remailer.paranoici.org> - 2012-10-29 10:56 +0000
                Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-29 06:11 -0500
                Re: I Don?t Make Mistakes. I Use C rickman <gnuarm@gmail.com> - 2012-10-29 13:51 -0400
                Re: I Don?t Make Mistakes. I Use C Anonymous <nobody@remailer.paranoici.org> - 2012-10-29 20:45 +0000
                Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-30 04:20 -0500
                Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-30 04:16 -0500
    Re: I Don’t Make Mistakes. I Use C rickman <gnuarm@gmail.com> - 2012-10-25 10:04 -0400
      Re: I Don’t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-25 14:16 -0700
        Re: I Don’t Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-25 15:51 -1000
          Re: I Don’t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-25 20:14 -0700
            Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-25 23:11 -0500
              Re: I Don?t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-25 21:53 -0700
                Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-26 01:27 -0500
                Re: I Don?t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-26 07:06 -0700
                Re: I Don?t Make Mistakes. I Use C Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-10-26 11:34 -0500
                Re: I Don?t Make Mistakes. I Use C Bernd Paysan <bernd.paysan@gmx.de> - 2012-10-26 19:13 +0200
                Re: I Don?t Make Mistakes. I Use C Alex McDonald <blog@rivadpm.com> - 2012-10-27 04:49 -0700
                Re: I Don?t Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-25 21:20 -1000
            Re: I Don’t Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-25 21:23 -1000
              Re: I Don’t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-26 00:53 -0700
          Re: I Don’t Make Mistakes. I Use C "Stanley Daniel de Liver" <notagoodone@invalid.org.invalid> - 2012-11-21 16:21 +0000
  Re: I Don't Make Mistakes. I Use C "Rod Pemberton" <do_not_have@notemailnotz.cnm> - 2012-10-24 06:55 -0400
    Re: I Don't Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-24 08:17 -1000
      Re: I Don't Make Mistakes. I Use C "Rod Pemberton" <do_not_have@notemailnotz.cnm> - 2012-10-25 00:23 -0400
        Re: I Don't Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-24 22:18 -0700
        Re: I Don't Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-24 21:47 -1000
          Re: I Don't Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-25 11:21 -0700
            Re: I Don't Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-25 08:43 -1000
              Re: I Don't Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-25 12:18 -0700
              Re: I Don't Make Mistakes. I Use C "Rod Pemberton" <do_not_have@notemailnotz.cnm> - 2012-10-26 19:55 -0400
                Re: I Don't Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-26 17:38 -1000
            Re: I Don't Make Mistakes. I Use C Brad Eckert <hwfwguy@gmail.com> - 2012-10-26 09:07 -0700
          Re: I Don't Make Mistakes. I Use C "Rod Pemberton" <do_not_have@notemailnotz.cnm> - 2012-10-26 19:56 -0400
            Re: I Don't Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-26 17:47 -1000
              Re: I Don't Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-26 22:04 -0700
                Re: I Don't Make Mistakes. I Use C visualforth@rocketmail.com - 2012-10-27 07:27 -0700
                Re: I Don't Make Mistakes. I Use C Bernd Paysan <bernd.paysan@gmx.de> - 2012-10-27 19:14 +0200
    Re: I Don't Make Mistakes. I Use C Brad Eckert <hwfwguy@gmail.com> - 2012-10-24 11:48 -0700
      Re: I Don't Make Mistakes. I Use C rickman <gnuarm@gmail.com> - 2012-10-25 19:14 -0400
  Re: I Don’t Make Mistakes. I Use C Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-10-24 10:41 -0700
    Re: I Don’t Make Mistakes. I Use C Pavel Klinkovsky <pavel.klinkovsky@gmail.com> - 2012-10-24 13:10 -0700
      Re: I Don’t Make Mistakes. I Use C "Elizabeth D. Rather" <erather@forth.com> - 2012-10-24 14:00 -1000
        Re: I Don’t Make Mistakes. I Use C Pavel Klinkovsky <pavel.klinkovsky@gmail.com> - 2012-10-24 23:54 -0700
      Re: I Don't Make Mistakes. I Use C "Rod Pemberton" <do_not_have@notemailnotz.cnm> - 2012-10-25 00:29 -0400
        Re: I Don't Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-24 22:25 -0700
          Re: I Don't Make Mistakes. I Use C Pavel Klinkovsky <pavel.klinkovsky@gmail.com> - 2012-10-24 23:57 -0700
        Re: I Don't Make Mistakes. I Use C Pavel Klinkovsky <pavel.klinkovsky@gmail.com> - 2012-10-25 00:11 -0700
    Re: I Don’t Make Mistakes. I Use C visualforth@rocketmail.com - 2012-10-24 16:14 -0700
      Re: I Don’t Make Mistakes. I Use C Paul Rubin <no.email@nospam.invalid> - 2012-10-24 17:16 -0700
        Re: I Don’t Make Mistakes. I Use C visualforth@rocketmail.com - 2012-10-24 17:47 -0700
      Re: I Don’t Make Mistakes. I Use C rickman <gnuarm@gmail.com> - 2012-10-25 10:17 -0400

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