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glennj's solution

to Darts in the Tcl Track

Published at Mar 03 2020 · 0 comments
Test suite


This exercise has changed since this solution was written.

Write a function that returns the earned points in a single toss of a Darts game.

Darts is a game where players throw darts to a target.

In our particular instance of the game, the target rewards with 4 different amounts of points, depending on where the dart lands:

  • If the dart lands outside the target, player earns no points (0 points).
  • If the dart lands in the outer circle of the target, player earns 1 point.
  • If the dart lands in the middle circle of the target, player earns 5 points.
  • If the dart lands in the inner circle of the target, player earns 10 points.

The outer circle has a radius of 10 units (This is equivalent to the total radius for the entire target), the middle circle a radius of 5 units, and the inner circle a radius of 1. Of course, they are all centered to the same point (That is, the circles are concentric) defined by the coordinates (0, 0).

Write a function that given a point in the target (defined by its real cartesian coordinates x and y), returns the correct amount earned by a dart landing in that point.

Submitting Incomplete Solutions

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Running the tests

To run the test suite, execute one of the following commands:

tclsh darts.test            # Will stop testing after the first failure.
RUN_ALL=1 tclsh darts.test  # Will run all tests and report all failures.

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Inspired by an exercise created by a professor Della Paolera in Argentina


#!/usr/bin/env tclsh
set version 2.2.0
package require tcltest
namespace import ::tcltest::*
source "darts.tcl"

proc fail_fast {} {
    return [expr {
        ![info exists ::env(RUN_ALL)]
        || [string is boolean -strict $::env(RUN_ALL)]
        && !$::env(RUN_ALL)

proc failed {} {
    return [expr {$::tcltest::numTests(Failed) > 0}]

if {[fail_fast]} {
    proc test args {
        if {[failed]} {::tcltest::configure -skip *}
        uplevel [list ::tcltest::test {*}$args]

proc cleanupTests {} {
    set failed [failed]
    uplevel 1 ::tcltest::cleanupTests
    if {$failed} {exit 1}

if {$::argv0 eq [info script]} {

    set cases {
        darts-1 "Missed target" -9 9 0
        darts-2 "On the outer circle" 0 10 1
        darts-3 "On the middle circle" -5 0 5
        darts-4 "On the inner circle" 0 -1 10
        darts-5 "Exactly on centre" 0 0 10
        darts-6 "Near the centre" -0.1 -0.1 10
        darts-7 "Just within the inner circle" 0.7 0.7 10
        darts-8 "Just outside the inner circle" 0.8 -0.8 5
        darts-9 "Just within the middle circle" -3.5 3.5 5
        darts-10 "Just outside the middle circle" -3.6 -3.6 1
        darts-11 "Just within the outer circle" -7.0 7.0 1
        darts-12 "Just outside the outer circle" 7.1 -7.1 0
        darts-13 "Asymmetric position between the inner and middle circles" 0.5 -4 5

    foreach {name description x y value} $cases {
        test $name $description -body {
            score $x $y
        } -returnCodes ok -result $value

proc score {x y} {
    set distance [expr {hypot($x, $y)}]
    if {$distance <=  1} {return 10}
    if {$distance <=  5} {return  5}
    if {$distance <= 10} {return  1}
    return 0

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