Perl Stack Trace（Devel :: Trace）

Question

我试着用Devel::Trace来获取perl堆栈跟踪信息，用它作为代码的调试器。

perl -d:Trace <pgm> 

使用$Devel::Trace::TRACE = 0;和Devel::Trace::trace('on'); Perl代码内也试过。但我无法得到踪迹。

有人可以举例说明在Perl代码中使用Devel::Trace。

Answer 1

Devel::Trace不会产生堆栈跟踪。相反，它会打印出当前正在执行的语句。例如：

$ cat script.pl 
    use feature 'say'; 
    my $foo = "bar"; 
    say $foo; 
$ perl -d:Trace script.pl 
>> script.pl:2:  my $foo = "bar"; 
>> script.pl:3:  say $foo; 
bar 

里面的代码，您可以打开跟踪和关闭特定的区域：

$ cat script.pl 
    use feature 'say'; 
    my $foo = "bar"; 
    for my $n (1 .. 3) { 
     local $Devel::Trace::TRACE = 0; 
     say $foo x $n; 
    } 
    say "That were some ${foo}s"; 
$ perl -d:Trace script.pl 
>> script.pl:2:  my $foo = "bar"; 
>> script.pl:3:  for my $n (1 .. 3) { 
>> script.pl:4:  local $Devel::Trace::TRACE = 0; 
bar 
>> script.pl:4:  local $Devel::Trace::TRACE = 0; 
barbar 
>> script.pl:4:  local $Devel::Trace::TRACE = 0; 
barbarbar 
>> script.pl:7:  say "That were some ${foo}s"; 
That were some bars 

正如你所看到的，say $foo x $n线不包括在跟踪输出当我转身的在该范围内追踪。

如果你想有一个堆栈跟踪（如“调用堆栈跟踪”），然后使用Carp模块：

$ cat script.pl 
    use Carp(); 

    foo("Hello World"); 

    sub foo { bar(@_) } 
    sub bar { baz(@_) } 
    sub baz { qux(@_) } 
    sub qux { Carp::cluck "Howdy!" } 
$ perl script.pl 
Howdy! at so1.pl line 8. 
     main::qux('Hello World') called at script.pl line 7 
     main::baz('Hello World') called at script.pl line 6 
     main::bar('Hello World') called at script.pl line 5 
     main::foo('Hello World') called at script.pl line 3