October 2022
Beginner to intermediate
390 pages
7h 5m
Chinese
Content preview from Perl语言入门（第8版）
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216
｜
第
11
章
在程序编译阶段，
Perl
看到这行代码后，会尝试找寻此模块的源代码并加载进来。现
在，
Perl
似乎突然多出了一些新函数，在程序接下来的部分都可以随意使用这些函数
了。此前的例子中我们需要的正是
basename
函数：
use File::Basename;
my $name = "/usr/local/bin/perl";
my $basename = basename $name; #
返回
'perl'
嗯，这样虽然在
Unix
上行得通，但如果我们的程序在
MacPerl
、
Windows
或
VMS
等
系统上运行呢？不必担心，这个模块会判断你当前用的是哪种操作系统，并且使用该
系统默认的文件命名规则。（当然，这时
$name
里存放的就是属于该系统的文件名字
符串了。）
此模块还提供了一些其他函数，比如
dirname
函数可以从文件全名里取得目录名称。
这个模块也能让你将文件名和扩展名分开，或者更改默认的文件名规则。
仅选用模块中的部分函数
如果想在已有程序里加上
File::Basename
模块，却发现该程序中已经有个叫
作
&dirname
的子程序——也就是说，程序里现有的子程序和模块里的某个函数同
名。现在麻烦来了，通过使用模块而引入的
dirname
也是个
Perl
子程序，该如何与
自己写的同名子程序区分开来呢？
只需在
File::Basename
的
use
声明中加上导入列表来指明要导入的函数清单，就不
会自动导入所有函数了。在此，我们只需要
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.