[英]How can I golf this Perl subroutine that does a substitution?
I have the following subroutine in Perl to substitute "abc" for "xyz" in a string: 我在Perl中有以下子程序用“abc”替换字符串中的“xyz”:
sub mySubst {
my ($str) = @_;
$str =~ s|abc|xyz|ig;
return $str;
}
It works, but seems way too verbose for Perl. 它有效,但对于Perl来说似乎太冗长了。 How can I tighten it up? 我怎样才能把它收紧?
What you have is fine. 你有什么好。
shift
would also work, but changes @_ (may or may not be what you want.) There's a discussion on PerlMonks about shift vs @_ that you might be interested in. 列表赋值是一种很好的方法(基本上是标准方式。)使用shift
也可以工作,但是更改@_(可能是也可能不是你想要的。) 有关PerlMonks的讨论关于转换vs @_你可能会感兴趣。 local $_ = shift;
你需要做local $_ = shift;
or local ($_) = @_;
或local ($_) = @_;
which doesn't add much.) 这不会增加太多。) return
. 当人们使用明确的return
时,我喜欢它。 It's a warm fuzzy. 这是一个温暖的模糊。 Go with it. 去吧。 I think you're on the right track. 我认为你走在正确的轨道上。
If you're looking for golf, and not production code. 如果您正在寻找高尔夫,而不是生产代码。
use strict; ## Not really required ;)
use warnings; ## Not really required ;)
sub f{local$_=pop,s/foo/bar/ig;$_}
print f 'foobarbaz';
You could write: 你可以写:
sub mySubst { (map { s|abc|xyz|ig; $_ } "$_[0]" )[0] }
but unless this is an exercise in obfuscation, I would say go with what you have. 但除非这是一个混淆的练习,否则我会说你有你的东西。 Remember, you are not writing the program for the computer. 请记住,您没有为计算机编写程序。
This is how I would render that subroutine more idiomatically: 这是我如何更惯用地渲染该子例程:
sub mySubst {
(my $str = shift) =~ s|abc|xyz|ig;
return $str;
}
I think too verbose sounds like not enough obfuscation which I disagree. 我觉得太冗长的声音就像我不同意的那样混淆不够 。 As for tightening it up I'd suggest something along the lines of: 至于收紧它,我建议采取以下措施:
sub replaceBeginningWithEnd {
my $text = shift;
return if not defined($text);
$text =~ s/abc/xyz/ig;
return $text;
}
No one gave the Perl idiom for this yet. 没有人为此提供Perl成语。 This replicates the behavior of the original code by modifiying a copy: 这通过修改副本来复制原始代码的行为:
(my $new_str = $old_str) =~ s/abc/xyz/ig;
If I had to put that into a subroutine, which I think is kinda silly for such a simple operation, I guess that would be: 如果我不得不把它放到一个子程序中,我认为这对于这么简单的操作来说有点傻,我想那会是:
sub foo { (my $s = $_[0]) =~ s/abc/xyz/ig; $s }
However, if I was doing something silly like this, I wouldn't make a named subroutine for it. 但是,如果我这样做傻事,我就不会为它做一个命名的子程序。 I'd make a subroutine to make the subroutine for me so I don't need a new named sub for every possible sort of replacement: 我做了一个子程序来为我创建子程序,所以我不需要为每种可能的替换方式添加一个新的命名子:
sub make_sub {
my( $regex, $replacement ) = @_;
# season to taste with error checking
sub {
(my $s = $_[0]) =~ s/$regex/$replacement/ig; $s
};
}
my $replacer = make_sub( qr/abc/, 'xyz' );
my $new = $replacer->( $string );
what is the sub for? 什么是子? just do it like this 就这样做吧
$str =~ s|abc|xyz|ig;
You can omit the return keyword: 您可以省略return关键字:
sub mySubst {
my ($str) = @_;
$str =~ s|abc|xyz|ig;
$str;
}
It is also possible to use the default variable ( $_
) : 也可以使用默认变量( $_
):
sub mySubst {
local $_ = shift; # or my starting from Perl 5.10
s|abc|xyz|ig;
$_;
}
To avoid changing the originals, you could write 为避免更改原件,您可以写
sub mySubst { map { (my $s=$_) =~ s|abc|xyz|ig; $s } @_ }
or 要么
sub mySubst { my @a = @_; map { s|abc|xyz|ig; $_ } @a }
or to borrow from Sinan's answer, except discarding the temporary array explicitly: 或借用思南的答案,除了明确丢弃临时阵列:
sub mySubst { map { s|abc|xyz|ig; $_ } my(undef) = @_ }
but the syntax is still a little noisy. 但语法仍然有点吵。 Because it uses map
, be sure to call it in list context: 因为它使用map
,所以一定要在列表上下文中调用它:
my($result) = mySubst $str; # NOT my $one = mySubst $str;
If you expect to mostly call mySubst
with a single argument but want to handle cases of one or more arguments, then you could write 如果您希望主要使用单个参数调用mySubst
但想要处理一个或多个参数的情况,那么您可以编写
sub mySubst {
s|abc|xyz|ig for my @a = @_;
wantarray ? @a : $a[0];
}
but that starts up the stuttering again. 但这又开始了口吃。
If you want to update the parameter itself, use the alias semantics of Perl's subs as documented in perlsub : 如果你要更新的参数本身,使用Perl的潜艇别名语义中记录perlsub :
The array
@_
is a local array, but its elements are aliases for the actual scalar parameters. 数组@_
是一个本地数组,但它的元素是实际标量参数的别名。 In particular, if an element$_[0]
is updated, the corresponding argument is updated (or an error occurs if it is not updatable). 特别是,如果更新元素$_[0]
则更新相应的参数(如果不可更新,则会发生错误)。
So you could write 所以你可以写
sub mySubst { $_[0] =~ s|abc|xyz|ig }
or even 甚至
sub mySubst { map { s|abc|xyz|ig; $_ } @_ }
Example usage: 用法示例:
$str = "fooabcbar";
mySubst $str;
print $str, "\n";
Output: 输出:
fooxyzbar
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