在Perl中，是否可能知道在双引号中被其值替换的变量？

假设你已经：-

my $variable = 'Value';

my $text = "$variable is stored inside scalar variable.\n";

print "$text\n";

现在，当您看到输出时，会发现值存储在标量变量中

我想得到的信息是，这里$variable被替换为'value'。可能吗

我实际上是想得到所有这些语句的列表，其中一个变量被替换为它的值。例如，假设文件1包含上述代码。文件2包含以下内容：

print "Welcome to $website!!";

文件3已-通过电子邮件发送打印输出

我正在尝试获取文件1中的$text=$变量存储在标量变量中的详细信息。\n；文件2已经打印了欢迎访问$website

文件3不计算在内。

您不能这样做

守则：

我的$variable='Value'； my$text=$变量存储在标量变量中。\n

分配$text时，$变量将被其值替换。$text是一个文本字符串

更新我的答案

我想你会喜欢这个：

#!/usr/bin/perl

use warnings;
use strict;

package myVariable;
use overload
    qw("") => \&asString,
    qw(+) => \&append;

sub new (;+[$]){
    my $class = shift;
    my $self = {
        'have_var' => 0,
        'string' => '',
    };
    &init($self, @_);

    bless $self,$class;
}   

sub init {
    my $class = shift;

    for(@_) {
        if(ref($_) eq ref(\"")) {
            $class->{'have_var'}++;
            $class->{'string'} .= $$_;
        } else {
            $class->{'string'} .= $_;
        }
    }
}
sub asString {
    my $class = shift;
    return $class->{'string'};
}

sub APPEND {
    my $class = shift;
    $class->init(@_);
}

sub HAVE_VAR {
    my $class = shift;
    return $class->{'have_var'};
}

package main;
my $variable_1 = "Value";
my $variable_2 = "newVal";
my $variable_3 = "otherVal";

my $text = myVariable->new(\$variable_1, " ", \$variable_2, " this is text! ", \$variable_3);

my $appendString = " appendString";
$text->APPEND(\$appendString);

print "text content is :  [$text]\n";

print "there are ", $text->HAVE_VAR, " variables in \$text";

你会得到

text content is :  [Value newVal this is text! otherVal appendString]
there are 4 variables in $text

你不能那样做

守则：

我的$variable='Value'； my$text=$变量存储在标量变量中。\n

分配$text时，$变量将被其值替换。$text是一个文本字符串

更新我的答案

我想你会喜欢这个：

#!/usr/bin/perl

use warnings;
use strict;

package myVariable;
use overload
    qw("") => \&asString,
    qw(+) => \&append;

sub new (;+[$]){
    my $class = shift;
    my $self = {
        'have_var' => 0,
        'string' => '',
    };
    &init($self, @_);

    bless $self,$class;
}   

sub init {
    my $class = shift;

    for(@_) {
        if(ref($_) eq ref(\"")) {
            $class->{'have_var'}++;
            $class->{'string'} .= $$_;
        } else {
            $class->{'string'} .= $_;
        }
    }
}
sub asString {
    my $class = shift;
    return $class->{'string'};
}

sub APPEND {
    my $class = shift;
    $class->init(@_);
}

sub HAVE_VAR {
    my $class = shift;
    return $class->{'have_var'};
}

package main;
my $variable_1 = "Value";
my $variable_2 = "newVal";
my $variable_3 = "otherVal";

my $text = myVariable->new(\$variable_1, " ", \$variable_2, " this is text! ", \$variable_3);

my $appendString = " appendString";
$text->APPEND(\$appendString);

print "text content is :  [$text]\n";

print "there are ", $text->HAVE_VAR, " variables in \$text";

你会得到

text content is :  [Value newVal this is text! otherVal appendString]
there are 4 variables in $text

---

这将在读取变量时显示回溯。够近了吗

package Peekaboo;
require Tie::Scalar;
our @ISA = 'Tie::StdScalar';
use Carp 'cluck';
sub FETCH { cluck }

package main;
my $variable = 'Value';
tie $variable, 'Peekaboo';
my $text = "$variable is stored inside scalar variable.\n";

---

如果没有，那么您可能需要和。我不知道如何使用它们。

每当读取变量时，都会显示回溯。够近了吗

package Peekaboo;
require Tie::Scalar;
our @ISA = 'Tie::StdScalar';
use Carp 'cluck';
sub FETCH { cluck }

package main;
my $variable = 'Value';
tie $variable, 'Peekaboo';
my $text = "$variable is stored inside scalar variable.\n";

---

如果没有，那么您可能需要和。我不知道如何使用它们。

解析源代码可以让你半途而废

use PPI qw();

sub walk {
    my ($ref) = @_;
    if ($ref->can('children')) {
        for my $c ($ref->children) {
            if ($c->can('interpolations')) {
                if ($c->interpolations) {
                    say sprintf "Found interpolations of variables at line %d column %d and the string was:\n%s\n", $c->line_number, $c->column_number, $c->content;
                }
            }
            walk($c);
        }
    }
    return;
}

walk(PPI::Document->new(\(join '', *DATA->getlines)));


__DATA__
my $variable = 'Value';

my $text = "$variable is stored inside scalar variable.\n";

print "$text\n";

结果:

Found interpolations of variables at line 3 column 12 and the string was:
"$variable is stored inside scalar variable.\n"

Found interpolations of variables at line 5 column 7 and the string was:
"$text\n"

从插值表达式得出变量名的结论并不简单。您的示例只有简单的标量，但请考虑：

 "$foo[0]"         # @foo single lookup
 "@foo[0,1]"       # @foo slice 
 "$foo{key}"       # %foo single lookup
 "@foo{qw(k1 k2)}" # %foo slice

---

表达式和引用链中的变量/表达式会使事情变得更加复杂。

解析源代码会让您半途而废

use PPI qw();

sub walk {
    my ($ref) = @_;
    if ($ref->can('children')) {
        for my $c ($ref->children) {
            if ($c->can('interpolations')) {
                if ($c->interpolations) {
                    say sprintf "Found interpolations of variables at line %d column %d and the string was:\n%s\n", $c->line_number, $c->column_number, $c->content;
                }
            }
            walk($c);
        }
    }
    return;
}

walk(PPI::Document->new(\(join '', *DATA->getlines)));


__DATA__
my $variable = 'Value';

my $text = "$variable is stored inside scalar variable.\n";

print "$text\n";

结果:

Found interpolations of variables at line 3 column 12 and the string was:
"$variable is stored inside scalar variable.\n"

Found interpolations of variables at line 5 column 7 and the string was:
"$text\n"

从插值表达式得出变量名的结论并不简单。您的示例只有简单的标量，但请考虑：

 "$foo[0]"         # @foo single lookup
 "@foo[0,1]"       # @foo slice 
 "$foo{key}"       # %foo single lookup
 "@foo{qw(k1 k2)}" # %foo slice

---

表达式和引用链中的变量/表达式使事情变得更加复杂。

您已经在$variable中存储了值，那么为什么需要在$text中检查相同的值。这只是一种情况。正如我在最后一行中所说，我将在不同的文件中查找所有此类语句，并应列出一个列表。是的。我们需要一个简单的代码示例来理解这个问题。只要检查$variable是否没有任何值，perl就会在编译脚本时显示一个未初始化的警告。@Aiswarya是否要分析其他perl代码？您已经在$variable中存储了值，那么为什么需要在$text中检查相同的值。这是就一个案子。正如我在最后一行中所说，我将在不同的文件中查找所有此类语句，并应列出一个列表。是的。我们需要一个简单的代码示例来理解这个问题。只要检查$variable是否没有任何值，perl就会在编译脚本时显示未初始化的警告。@Aiswarya是否要分析其他perl代码？