使用exercism.io成为更好的程序员

2014年5月19日，作者：David Farrell

在过去的一周里，我一直在尝试使用编程练习应用 exercism.io。我在去年12月通过Gabor 博客了解到它，但直到现在才尝试。我希望我没有等那么久，因为exercism非常有乐趣。

exercism是如何工作的

exercism附带一个命令行应用程序，可以下载编程练习并将您的编码答案提交到exercism网站。每个编程练习都附带一个readme文件和一个测试文件。为了完成练习，您需要编写一个Perl模块，以便通过所有测试。

当您完成并通过命令行应用程序提交了您的Perl模块后，您和其他程序员可以“吹毛求疵”您的代码并对其进行评论。一旦您觉得已经收到了足够的评论，您就可以最终提交您的作品并查看其他程序员对同一练习的解决方案。关键是您一次只能收到一个编程练习，并且必须在完成当前练习之前才能访问另一个练习。

Perl的TIMTOWTDI特性意味着对于练习有多种正确答案，您经常可以从查看其他程序员的解决方案中学习到一些东西。例如，在一个练习中，我仅使用正则表达式，但发现更简单的转义运算符效果一样好。练习难度从简单到困难不等，但真正的挑战是找到一个干净、通用的解决方案。

尝试一下

下载您平台上的最新二进制文件并提取它。打开命令行并输入

$ exercism demo

这将获取第一个练习（撰写本文时为“Bob”）。测试文件和readme文件位于“perl5/bob/”中。打开readme文件，您会看到

# Bob

Bob is a lackadaisical teenager. In conversation, his responses are very limited.

Bob answers 'Sure.' if you ask him a question.

He answers 'Woah, chill out!' if you yell at him.

He says 'Fine. Be that way!' if you address him without actually saying anything.

He answers 'Whatever.' to anything else.

## Instructions

Run the test file, and fix each of the errors in turn. When you get the first test to pass, go to the first pending or skipped test, and make that pass as well. When all of the tests are passing, feel free to submit. 

Remember that passing code is just the first step. The goal is to work towards a solution that is as readable and expressive as you can make it. 

Please make your solution as general as possible. Good code doesn't just pass the test suite, it works with any input that fits the specification.

Have fun!

## Source

Inspired by the 'Deaf Grandma' exercise in Chris Pine's Learn to Program tutorial. [view source](http://pine.fm/LearnToProgram/?Chapter=06)

要运行测试文件，请切换到练习目录并使用prove

$ cd perl5/bob
$ prove bob.t

这将得到以下输出

bob.t .. 1/22 Bailout called.  Further testing stopped:  You need to create a module called Bob.pm with a function called hey() that gets one parameter: The text Bob hears.

#   Failed test 'missing Bob.pm'
#   at bob.t line 37.
FAILED--Further testing stopped: You need to create a module called Bob.pm with a function called hey() that gets one parameter: The text Bob hears.

让我们创建一个基本的Bob.pm模块

package Bob;
use warnings;
use strict;

sub hey {
    my $input = shift;
}

1;

这是解决方案的框架。我们的“hey”子程序返回它接收到的第一个输入。重新运行prove，我们得到以下输出

$ prove bob.t
bob.t .. 1/22 
#   Failed test 'stating something: Tom-ay-to, tom-aaaah-to.'
#   at bob.t line 52.
#          got: 'Tom-ay-to, tom-aaaah-to.'
#     expected: 'Whatever.'

...

# Looks like you failed 19 tests of 22.
bob.t .. Dubious, test returned 19 (wstat 4864, 0x1300)
Failed 19/22 subtests 

Test Summary Report
-------------------
bob.t (Wstat: 4864 Tests: 22 Failed: 19)
  Failed tests:  4-22
  Non-zero exit status: 19
Files=1, Tests=22,  1 wallclock secs ( 0.02 usr  0.00 sys +  0.04 cusr  0.00 csys =  0.06 CPU)
Result: FAIL