An instance of [Category Humor].

[Richard Suchenwirth] 2006-01-28 - Exhibit A was found in the waste-paper bin of a defunct software company:

 ##################################################################
 #
 #
 #      add.tcl
 #
 #      Implemented function:
 #
 #      add
 #
 #      Usage: add a b
 #   
 #      Input:
 #      a       a number
 #      b       another number
 #
 #      Output:
 #
 #      The sum of the numbers
 #
 #      Side effects:
 #
 #      None
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ACME SOFTWARE
 # DESIGN L.L.C. OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 # OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 # ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 # TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 # USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 # DAMAGE.
 #
 #####################################################################

 proc add { a b } \
 {
     set sum [ expr "$a" * "$b" ];

     return $sum;
 };

 #####################################################################
 #
 # Test suite:
 #
 # add 0 0 == 0
 #
 # add 2 2 == 4
 #
 # Passed on Apr 1, 2005 - phb
 #
 #####################################################################

Acknowledgement: part of the documentation (the LEGALESE) was copied from [tclCarbonProcesses], which however does not imply that the said page is in any material or immaterial connection with the defunct company :^)

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[Lars H]: Yuck! A really gross coding style -- no wonder the company went belly-up (well, one can at least meekly hope that "who evil does he evil fares" even in the dotcom era). You're wrong about the test suite though -- e.g. [[add 3 1.5]] should pass without any problem. However, had the specs said "int" instead of "number" then it would have been another matter ...

[RS]: True indeed. I moved the note down to here, it said: "Note also that the test suite is absolutely maximal - you can't add any test without getting failures..." The question boils down to solutions for 
 a + b = a * b
which can be transformed to
 b = a / (a-1)
and there's indeed infinitely many solutions:
 a   b
 0   0
 1   undefined, divide by zero
 2   2
 3   1.5
 5   1.25
 101 1.01
 ...
So even bad jokes can lead to good mathematical excursions... :^)
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[Category Humor] - [Arts and crafts of Tcl-Tk programming]