Perl的主要包 – 块语法 – pragma和BEGIN / END块

我看到了这个问题： Is there any difference between “standard” and block package declaration?并考虑了主要的包装.当我编写脚本时,例如：

---- begin of the file ---
#!/usr/bin/perl  #probably removed by shell?
my $var; #defined from now up to the end of file
...
---- end of the file ----

这自动进入主包,所以我理解正确的下一个发生.

---- begin of the file ---
{ #<-- 1st line
  package main;
  my $var; #variable transformed to block scope - "up to the end of block"
  ...
} # <-- last line
---- end of the file ----

这相当于

---- begin of the file ---
package main { #1st line
  my $var; #variable block scope
  ...
} #last line
---- end of the file ----

问题1：以上是对的吗？主包发生了什么？

现在是BEGIN / END块和pragma.如果我理解的话,在编译阶段处理.所以有：

---- begin of the file ---
#!/usr/bin/perl
use strict;    #file scope
use warnings;  #file scope
my $var; #defined from now up to the end of file
BEGIN {
    say $var; #the $var is not known here - but it is declared
}
...
---- end of the file ----

声明$var,但在这里

---- begin of the file ---
#!/usr/bin/perl
use strict;    #file scope
use warnings;  #file scope

BEGIN {
    say $var; #the $var is not known here - but "requires explicit package name" error
}

my $var; #defined from now up to the end of file
...
---- end of the file ----

$var未声明.

那么如何将上述内容翻译成“默认主包”？

它始终是：

---- begin of the file ---
{
  package main;
  use strict;    #block scope ???
  use warnings;  #block scope ???
  my $var; #defined from now up to the end of block

  BEGIN { #NESTED???
    say $var; #the $var is not known here - but declared
  }
  ...
}
---- end of the file ----

相当于

---- begin of the file ---
package main {
  use strict;    #block scope
  use warnings;  #block scope
  my $var; #defined from now up to the end of block

  BEGIN {  #NESTED block
    say $var;
  }
  ...
}
---- end of the file ----

问题是 – 在这里_ANY使用类似的东西：

---- begin of the file ---
  use strict;   #always should be at the START OF THE FILE - NOT IN BLOCKS?
  use warnings;

  #not NESTED
  BEGIN {
  }

  package main {
     my $var;
  }

所以问题是：

>在BLOCK语法的上下文中,如何处理pragma,BEGIN / END / CHECK块和主包？
>将“文件范围”更改为“块范围”时 – 或者如果它没有更改,“标准主程序包”到“主程序包{block}”的等效转换是什么？

和最后一个代码：

---- begin of the file ---
  use strict;   #always should be at the START OF THE FILE - NOT IN BLOCKS?
  use warnings;
  my $var;

  #not NESTED
  BEGIN {
  }

  package main {

  }

我的$var如何进入主包？所以这被翻译成：

---- begin of the file ---
  use strict;   #always should be at the START OF THE FILE - NOT IN BLOCKS?
  use warnings;

  #not NESTED
  BEGIN {
  }

  package main {
      my $var; #### GETS HERE????
  }

对不起文字墙…

use warnings;
use strict;
package main {
    my $var = 'this';
}
$var; # error,$var was not declared in this scope
say $main::var; # says nothing

use warnings;
 use strict;
 package main {
 # ...
 }

package main {
     use warnings;
     use strict;
     package main {
     # ...
     }
 }

package main {
     use warnings;
     use strict;
     {
     # ...
     }
 }