使用Go構建CLI命令：Cowsay

喜歡CLI應用程序嗎？不要錯過洛爾卡特教程也一樣！

考賽是您不可或缺的應用程序之一。

在上面的屏幕快照中，它基本上會生成帶有您傳遞給它的任何消息的母牛的ASCII圖片。fortune生成它。但這不僅限於牛域，它還可以打印企鵝，駝鹿和許多其他動物。

聽起來像是一個有用的應用程序，可移植到Go！

另外，我喜歡所附的普通英語許可證：

==============
cowsay License
==============

cowsay is distributed under the same licensing terms as Perl: the
Artistic License or the GNU General Public License.  If you don’t
want to track down these licenses and read them for yourself, use
the parts that I’d prefer:


(0) I wrote it and you didn’t.


(1) Give credit where credit is due if you borrow the code for some
other purpose.


(2) If you have any bugfixes or suggestions, please notify me so
that I may incorporate them.


(3) If you try to make money off of cowsay, you suck.

讓我們從定義問題開始。我們想通過管道接受輸入，然後讓我們的牛說出來。

第一次迭代從管道讀取用戶輸入，然後將其打印回去。沒有太多複雜。

package main

import (
“bufio”
“fmt”
“io”
“os”
)


func main() {
info, _ := os.Stdin.Stat()


<span style="color:#66d9ef">if</span> <span style="color:#a6e22e">info</span>.<span style="color:#a6e22e">Mode</span>()<span style="color:#f92672">&amp;</span><span style="color:#a6e22e">os</span>.<span style="color:#a6e22e">ModeCharDevice</span> <span style="color:#f92672">!=</span> <span style="color:#ae81ff">0</span> {
	<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>(<span style="color:#e6db74">"The command is intended to work with pipes."</span>)
	<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>(<span style="color:#e6db74">"Usage: fortune | gocowsay"</span>)
	<span style="color:#66d9ef">return</span>
}

<span style="color:#a6e22e">reader</span> <span style="color:#f92672">:=</span> <span style="color:#a6e22e">bufio</span>.<span style="color:#a6e22e">NewReader</span>(<span style="color:#a6e22e">os</span>.<span style="color:#a6e22e">Stdin</span>)
<span style="color:#66d9ef">var</span> <span style="color:#a6e22e">output</span> []<span style="color:#66d9ef">rune</span>

<span style="color:#66d9ef">for</span> {
	<span style="color:#a6e22e">input</span>, <span style="color:#a6e22e">_</span>, <span style="color:#a6e22e">err</span> <span style="color:#f92672">:=</span> <span style="color:#a6e22e">reader</span>.<span style="color:#a6e22e">ReadRune</span>()
	<span style="color:#66d9ef">if</span> <span style="color:#a6e22e">err</span> <span style="color:#f92672">!=</span> <span style="color:#66d9ef">nil</span> <span style="color:#f92672">&amp;&amp;</span> <span style="color:#a6e22e">err</span> <span style="color:#f92672">==</span> <span style="color:#a6e22e">io</span>.<span style="color:#a6e22e">EOF</span> {
		<span style="color:#66d9ef">break</span>
	}
	<span style="color:#a6e22e">output</span> = append(<span style="color:#a6e22e">output</span>, <span style="color:#a6e22e">input</span>)
}

<span style="color:#66d9ef">for</span> <span style="color:#a6e22e">j</span> <span style="color:#f92672">:=</span> <span style="color:#ae81ff">0</span>; <span style="color:#a6e22e">j</span> &lt; len(<span style="color:#a6e22e">output</span>); <span style="color:#a6e22e">j</span><span style="color:#f92672">++</span> {
	<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Printf</span>(<span style="color:#e6db74">"%c"</span>, <span style="color:#a6e22e">output</span>[<span style="color:#a6e22e">j</span>])
}

}

我們想念這頭牛，還需要將消息包裝成一個氣球，格式正確。

這是我們程序的第一次迭代：

package main

import (
“bufio”
“fmt”
“io”
“os”
“strings”
“unicode/utf8”
)


// buildBalloon takes a slice of strings of max width maxwidth
// prepends/appends margins on first and last line, and at start/end of each line
// and returns a string with the contents of the balloon
func buildBalloon(lines []string, maxwidth int) string {
var borders []string
count := len(lines)
var ret []string


<span style="color:#a6e22e">borders</span> = []<span style="color:#66d9ef">string</span>{<span style="color:#e6db74">"/"</span>, <span style="color:#e6db74">"\\"</span>, <span style="color:#e6db74">"\\"</span>, <span style="color:#e6db74">"/"</span>, <span style="color:#e6db74">"|"</span>, <span style="color:#e6db74">"&lt;"</span>, <span style="color:#e6db74">"&gt;"</span>}

<span style="color:#a6e22e">top</span> <span style="color:#f92672">:=</span> <span style="color:#e6db74">" "</span> <span style="color:#f92672">+</span> <span style="color:#a6e22e">strings</span>.<span style="color:#a6e22e">Repeat</span>(<span style="color:#e6db74">"_"</span>, <span style="color:#a6e22e">maxwidth</span><span style="color:#f92672">+</span><span style="color:#ae81ff">2</span>)
<span style="color:#a6e22e">bottom</span> <span style="color:#f92672">:=</span> <span style="color:#e6db74">" "</span> <span style="color:#f92672">+</span> <span style="color:#a6e22e">strings</span>.<span style="color:#a6e22e">Repeat</span>(<span style="color:#e6db74">"-"</span>, <span style="color:#a6e22e">maxwidth</span><span style="color:#f92672">+</span><span style="color:#ae81ff">2</span>)

<span style="color:#a6e22e">ret</span> = append(<span style="color:#a6e22e">ret</span>, <span style="color:#a6e22e">top</span>)
<span style="color:#66d9ef">if</span> <span style="color:#a6e22e">count</span> <span style="color:#f92672">==</span> <span style="color:#ae81ff">1</span> {
	<span style="color:#a6e22e">s</span> <span style="color:#f92672">:=</span> <span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Sprintf</span>(<span style="color:#e6db74">"%s %s %s"</span>, <span style="color:#a6e22e">borders</span>[<span style="color:#ae81ff">5</span>], <span style="color:#a6e22e">lines</span>[<span style="color:#ae81ff">0</span>], <span style="color:#a6e22e">borders</span>[<span style="color:#ae81ff">6</span>])
	<span style="color:#a6e22e">ret</span> = append(<span style="color:#a6e22e">ret</span>, <span style="color:#a6e22e">s</span>)
} <span style="color:#66d9ef">else</span> {
	<span style="color:#a6e22e">s</span> <span style="color:#f92672">:=</span> <span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Sprintf</span>(<span style="color:#e6db74">`%s %s %s`</span>, <span style="color:#a6e22e">borders</span>[<span style="color:#ae81ff">0</span>], <span style="color:#a6e22e">lines</span>[<span style="color:#ae81ff">0</span>], <span style="color:#a6e22e">borders</span>[<span style="color:#ae81ff">1</span>])
	<span style="color:#a6e22e">ret</span> = append(<span style="color:#a6e22e">ret</span>, <span style="color:#a6e22e">s</span>)
	<span style="color:#a6e22e">i</span> <span style="color:#f92672">:=</span> <span style="color:#ae81ff">1</span>
	<span style="color:#66d9ef">for</span> ; <span style="color:#a6e22e">i</span> &lt; <span style="color:#a6e22e">count</span><span style="color:#f92672">-</span><span style="color:#ae81ff">1</span>; <span style="color:#a6e22e">i</span><span style="color:#f92672">++</span> {
		<span style="color:#a6e22e">s</span> = <span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Sprintf</span>(<span style="color:#e6db74">`%s %s %s`</span>, <span style="color:#a6e22e">borders</span>[<span style="color:#ae81ff">4</span>], <span style="color:#a6e22e">lines</span>[<span style="color:#a6e22e">i</span>], <span style="color:#a6e22e">borders</span>[<span style="color:#ae81ff">4</span>])
		<span style="color:#a6e22e">ret</span> = append(<span style="color:#a6e22e">ret</span>, <span style="color:#a6e22e">s</span>)
	}
	<span style="color:#a6e22e">s</span> = <span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Sprintf</span>(<span style="color:#e6db74">`%s %s %s`</span>, <span style="color:#a6e22e">borders</span>[<span style="color:#ae81ff">2</span>], <span style="color:#a6e22e">lines</span>[<span style="color:#a6e22e">i</span>], <span style="color:#a6e22e">borders</span>[<span style="color:#ae81ff">3</span>])
	<span style="color:#a6e22e">ret</span> = append(<span style="color:#a6e22e">ret</span>, <span style="color:#a6e22e">s</span>)
}

<span style="color:#a6e22e">ret</span> = append(<span style="color:#a6e22e">ret</span>, <span style="color:#a6e22e">bottom</span>)
<span style="color:#66d9ef">return</span> <span style="color:#a6e22e">strings</span>.<span style="color:#a6e22e">Join</span>(<span style="color:#a6e22e">ret</span>, <span style="color:#e6db74">"\n"</span>)

}


// tabsToSpaces converts all tabs found in the strings
// found in the lines slice to 4 spaces, to prevent misalignments in
// counting the runes
func tabsToSpaces(lines []string) []string {
var ret []string
for _, l := range lines {
l = strings.Replace(l, “\t”, "    ", -1)
ret = append(ret, l)
}
return ret
}


// calculatemaxwidth given a slice of strings returns the length of the
// string with max length
func calculateMaxWidth(lines []string) int {
w := 0
for _, l := range lines {
len := utf8.RuneCountInString(l)
if len > w {
w = len
}
}


<span style="color:#66d9ef">return</span> <span style="color:#a6e22e">w</span>

}


// normalizeStringsLength takes a slice of strings and appends
// to each one a number of spaces needed to have them all the same number
// of runes
func normalizeStringsLength(lines []string, maxwidth int) []string {
var ret []string
for _, l := range lines {
s := l + strings.Repeat(" ", maxwidth-utf8.RuneCountInString(l))
ret = append(ret, s)
}
return ret
}


func main() {
info, _ := os.Stdin.Stat()


<span style="color:#66d9ef">if</span> <span style="color:#a6e22e">info</span>.<span style="color:#a6e22e">Mode</span>()<span style="color:#f92672">&amp;</span><span style="color:#a6e22e">os</span>.<span style="color:#a6e22e">ModeCharDevice</span> <span style="color:#f92672">!=</span> <span style="color:#ae81ff">0</span> {
	<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>(<span style="color:#e6db74">"The command is intended to work with pipes."</span>)
	<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>(<span style="color:#e6db74">"Usage: fortune | gocowsay"</span>)
	<span style="color:#66d9ef">return</span>
}

<span style="color:#66d9ef">var</span> <span style="color:#a6e22e">lines</span> []<span style="color:#66d9ef">string</span>

<span style="color:#a6e22e">reader</span> <span style="color:#f92672">:=</span> <span style="color:#a6e22e">bufio</span>.<span style="color:#a6e22e">NewReader</span>(<span style="color:#a6e22e">os</span>.<span style="color:#a6e22e">Stdin</span>)

<span style="color:#66d9ef">for</span> {
	<span style="color:#a6e22e">line</span>, <span style="color:#a6e22e">_</span>, <span style="color:#a6e22e">err</span> <span style="color:#f92672">:=</span> <span style="color:#a6e22e">reader</span>.<span style="color:#a6e22e">ReadLine</span>()
	<span style="color:#66d9ef">if</span> <span style="color:#a6e22e">err</span> <span style="color:#f92672">!=</span> <span style="color:#66d9ef">nil</span> <span style="color:#f92672">&amp;&amp;</span> <span style="color:#a6e22e">err</span> <span style="color:#f92672">==</span> <span style="color:#a6e22e">io</span>.<span style="color:#a6e22e">EOF</span> {
		<span style="color:#66d9ef">break</span>
	}
	<span style="color:#a6e22e">lines</span> = append(<span style="color:#a6e22e">lines</span>, string(<span style="color:#a6e22e">line</span>))
}

<span style="color:#66d9ef">var</span> <span style="color:#a6e22e">cow</span> = <span style="color:#e6db74">`         \  ^__^

          \ (oo)_______
	    (__)\       )/

	        ||----w |
	        ||     ||
		`


<span style="color:#a6e22e">lines</span> = <span style="color:#a6e22e">tabsToSpaces</span>(<span style="color:#a6e22e">lines</span>)
<span style="color:#a6e22e">maxwidth</span> <span style="color:#f92672">:=</span> <span style="color:#a6e22e">calculateMaxWidth</span>(<span style="color:#a6e22e">lines</span>)
<span style="color:#a6e22e">messages</span> <span style="color:#f92672">:=</span> <span style="color:#a6e22e">normalizeStringsLength</span>(<span style="color:#a6e22e">lines</span>, <span style="color:#a6e22e">maxwidth</span>)
<span style="color:#a6e22e">balloon</span> <span style="color:#f92672">:=</span> <span style="color:#a6e22e">buildBalloon</span>(<span style="color:#a6e22e">messages</span>, <span style="color:#a6e22e">maxwidth</span>)
<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>(<span style="color:#a6e22e">balloon</span>)
<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>(<span style="color:#a6e22e">cow</span>)
<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>()

}

現在，通過添加一個劍龍

原始應用程序使用-f標誌以接受自定義圖形。因此，讓我們做同樣的事情處理命令行標誌。

我簡要地更改了以前的程序以進行介紹printFigure()

// printFigure given a figure name prints it.
// Currently accepts `cow` and `stegosaurus`.
func printFigure(name string) {

<span style="color:#66d9ef">var</span> <span style="color:#a6e22e">cow</span> = <span style="color:#e6db74">`         \  ^__^

          \ (oo)_______
	    (__)\       )/

	        ||----w |
	        ||     ||
		`


<span style="color:#66d9ef">var</span> <span style="color:#a6e22e">stegosaurus</span> = <span style="color:#e6db74">`         \                      .       .

          \                    / </span> <span style="color:#f92672">+</span> <span style="color:#e6db74">"" + .   .' " </span><span style="color:#e6db74">           \           .---.  &lt;    &gt; &lt;    &gt;  .---. </span><span style="color:#e6db74">            \          |    \  \ - ~ ~ - /  /    | </span><span style="color:#e6db74">          _____           ..-~             ~-..-~ </span><span style="color:#e6db74">         |     |   \~~~\\.'                     + ""</span> <span style="color:#f92672">+</span> <span style="color:#e6db74">./~/
        ---------   _/                         _/
       .’  O    \     /               /       \  "
      (_____,    </span> <span style="color:#f92672">+</span> <span style="color:#e6db74">"" + ._.'               |         }  \/~~~/ </span><span style="color:#e6db74">        + ""</span> <span style="color:#f92672">+</span> <span style="color:#e6db74">----.          /       }     |        /    __/
             </span> <span style="color:#f92672">+</span> <span style="color:#e6db74">"" + -.      |       /      |       /       + ""</span> <span style="color:#f92672">+</span> <span style="color:#e6db74">. ,|
                 ~-.|      /_ - ~ ^|      /- _      </span> <span style="color:#f92672">+</span> <span style="color:#e6db74">"" + ..-' </span><span style="color:#e6db74">                      |     /        |     /     ~-.      + ""</span> <span style="color:#f92672">+</span> <span style="color:#e6db74">-. _  _  _
                      ||        |__|         ~ - . _ _ _ _ _>

	`


<span style="color:#66d9ef">switch</span> <span style="color:#a6e22e">name</span> {
<span style="color:#66d9ef">case</span> <span style="color:#e6db74">"cow"</span>:
	<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>(<span style="color:#a6e22e">cow</span>)
<span style="color:#66d9ef">case</span> <span style="color:#e6db74">"stegosaurus"</span>:
	<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>(<span style="color:#a6e22e">stegosaurus</span>)
<span style="color:#66d9ef">default</span>:
	<span style="color:#a6e22e">fmt</span>.<span style="color:#a6e22e">Println</span>(<span style="color:#e6db74">"Unknown figure"</span>)
}

}

和改變main()接受一個標誌並將其傳遞給printFigure()：

func main() {
	//...

	var figure string
	flag.StringVar(&figure, "f", "cow", "the figure name. Valid values are `cow` and `stegosaurus`")
	flag.Parse()

<span style="color:#75715e">//...

	printFigure(figure)
fmt.Println()
}

玩

我認為我們處在一個好時機。我只想在系統上使它可用，而無需運行go run main.go，所以我只輸入go build和go install。

我現在可以與戈洛爾卡特和gocowsay


更多教程：


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