{"id":1728,"date":"2021-07-31T07:34:34","date_gmt":"2021-07-31T11:34:34","guid":{"rendered":"https:\/\/www.yorku.ca\/professor\/drsmith\/?p=1728"},"modified":"2021-08-01T13:45:05","modified_gmt":"2021-08-01T17:45:05","slug":"vpl-basic-custom-evaluation-example","status":"publish","type":"post","link":"https:\/\/www.yorku.ca\/professor\/drsmith\/2021\/07\/31\/vpl-basic-custom-evaluation-example\/","title":{"rendered":"VPL: Basic Custom Evaluation Example"},"content":{"rendered":"\n

Sometimes you need to go beyond the default settings in VPL. That means creating a custom<\/em> \"run\" and \"evaluate\" setup. Here, I'll simplify a great example by Dominique Tiebaut<\/a>, Emeritus prof at Smith College, written for an assignment in C. (archive<\/a>) We'll check a \"hello world\" example in C, but won't use the default evaluate.cases tool built into VPL. Instead, we'll develop three main files:<\/p>\n\n\n\n

  1. the student's submission template (\"requested files\")<\/li>
  2. the run script (vpl_run.sh)<\/li>
  3. the evaluate script (vpl_evaluate.sh)<\/li><\/ol>\n\n\n\n

    Let's begin with helloWorld.c, the student submission template:<\/p>\n\n\n\n

    \/* helloWorld.c\n * This is the student submission template.\n * Normally, the student would modify this template.  But not in this example.\n * Place this file in \"Gear\" -> Requested Files *\/\n\n#include <stdio.h>\n\nint main(void){\n   printf(\"hello world.\\n\");\n}<\/code><\/pre>\n\n\n\n
    You can test this file out manually, from a terminal on any computer with the gcc compiler tools like this:<\/p>\n\n\n\n
    \"hello
    typical example of compiling and running a 'C' hello world example outside of VPL.<\/figcaption><\/figure><\/div>\n\n\n\n
    gcc helloWorld.c -o helloWorld<\/code><\/p>\n\n\n\n
    and then executing it like this:<\/p>\n\n\n\n
    .\/helloWorld<\/code><\/p>\n\n\n\n
    and it will print<\/p>\n\n\n\n
    hello world.<\/code><\/p>\n\n\n\n
    to your screen.  Nothing complicated. The original example included multiple tests that required injecting input data into the student submission.  We're simply going to look at the output without providing any variations.  There are a few things to note about the two files, vpl_run.sh and vpl_evaluate, that we'll add to our assignment:<\/p>\n\n\n\n
    1. VPL will execute a bash script called vpl_execution<\/strong>.  This script is based on both your vpl_run.sh and vpl_evaluate.sh scripts.<\/li>
    2. Two<\/strong> instances of \"#!\/bin\/bash<\/strong>\" in each of the vpl_run.sh and vpl_evaluate.sh files.  The first one allows the script to run directly.  The second will feed subsequent commands into the vpl_execution script.  VPL will then run vpl_execution to test the student's submission and submit the grade.<\/li>
    3. Extra backslashes<\/strong>. The \"run<\/em> a bash script to create<\/em> a bash script\" process that we're following requires that some elements in your script be preceded by a '\\' (backslash).