如何有条件地使用 Perl 中的模块?

问题描述：

我想在 Perl 中做这样的事情:

I want to do something like this in Perl:

$Module1="ReportHashFile1"; # ReportHashFile1.pm
$Module2="ReportHashFile2"; # ReportHashFile2.pm

if(Condition1)
{
  use $Module1;
}
elsif(Condition2)
{
  use $Module2;
}

ReportHashFile*.pm 包含一个包 ReportHashFile*.

ReportHashFile*.pm contains a package ReportHashFile* .

还如何根据动态模块名称引用模块内部的数组?

Also how to reference an array inside module based on dynamic module name?

@Array= @$Module1::Array_inside_module;

无论如何我可以做到这一点.某种编译器指令?

Is there anyway I can achieve this. Some sort of compiler directive?

答

您可能会发现 if 模块对此很有用.

You might find the if module useful for this.

否则基本思想是使用require，它发生在运行时，而不是use，它发生在编译时.注意'

Otherwise the basic idea is to use require, which happens at run-time, instead of use, which happens at compile-time. Note that '

BEGIN {
    my $module = $condition ? $Module1 : $Module2;
    my $file = $module;
    $file =~ s[::][/]g;
    $file .= '.pm';
    require $file;
    $module->import;
}

至于寻址全局变量，如果您只是导出变量或将其返回给调用者的函数，则可能会更容易，您可以通过其非限定名称使用.否则也有可能使用一个方法并将其调用为 $Module->method_name.

As for addressing globals, it might be easier if you just exported the variable or a function returning it to the caller, which you could use by its unqualified name. Otherwise there's also the possibility of using a method and calling it as $Module->method_name.

或者，您可以使用 perlref 中记录的符号引用.但是，这通常是一种代码异味.

Alternatively, you could use symbolic references as documented in perlref. However, that's usually quite a code smell.

my @array = do {
    no strict 'refs';
    @{ ${ "${Module}::Array_inside_module" } };
};

如何有条件地使用 Perl 中的模块?

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