Tutorial Addendum on Perl - Allotment A - perlmod - Perl Modules

31 December 18:00

The calling program, IncRequireTest.pl,

 

    #- IncRequireTest.pl

    
#- Absorb (c) 1995 by Dr.  Yang

    
#

    
   print("

Testing require()...

");

    
   require("MyRequireLib.inc");

    
   require("MyRequireLib.inc");

    
   print("Author = $author

");

    
   &myRequireSub();

    
   print("

Testing do()...

");

    
   do("MyDoLib.inc");

    
   do("MyDoLib.inc");

    
   print("Author = $author

");

    
   &myDoSub();

    
   exit;

The achievement matches my expectation. The additional require() alarm didn t do any execution.

 

    Testing require()...

    
Printing from MyRequireLib.inc...

    
Author = Dr.  Yang

    
Printing from myRequireSub()...

    
Testing do()...

    
Printing from MyDoLib.inc...

    
Printing from MyDoLib.inc...

    
Author =  Yang

    
Printing from myDoSub()...

Using "package" to Make New Name Spaces

Name Space: A accumulation assemblage acclimated to abstract identifiers from altered parts

of the antecedent code. Name amplitude is aswell alleged package. There are several basic

rules about Name spaces:

There is a absence Name amplitude alleged "main". So after any appropriate coding,

every band of the antecedent cipher is in the "main" Name space.

You can use "package Name _space;" to avenue the accepted Name space, and


to access into the defined Name space. The accepted Name amplitude ends at the


end of the accepted cipher block, or end of the accepted file.

Identifiers from an additional Name amplitude can be accessed by prefixing the identifier

with the Name amplitude Name followed by a bifold colon, ::.

The appropriate attribute __PACKAGE__ contains the Name of the accepted Name space.

To verify those rules, I wrote the afterward program, PackageTest.pl,

 

    #- NameSpaceTest.pl

    
#- Absorb (c) 1995 by Dr.  Yang

    
#

    
   $j = "Java";                            # starting with main

    
   $f = "Fortran";

    
   $p = "Perl";

    
   $c = "C++";

    
   @list = ($j, $f, $p, $c);

    
   print("

In ",__PACKAGE__,"...

");

    
   print("list = ",join( ,  ,@list),"

"); 

    
   amalgamation Calendar;                       # entering Calendar

    
   $j = "January";

    
   $f = "February";

    
   $m = "March";

    
   $a = "April";

    
   @list = ($j, $f, $m, $a);

    
   print("

In ",__PACKAGE__,"...

");

    
   print("list = ",join( ,  ,@list),"

");

    
   {

    
      amalgamation Fruit;                       # entering Fruit

    
      $p = "peach";

    
      $o = "orange";

    
      $m = "mango";

    
      $a = "apple";

    
      @list = ($p, $o, $m, $a);

    
      print("

In ",__PACKAGE__,"...

");

    
      print("list = ",join( ,  ,@list),"

");

    
   }                                       # catastrophe Fruit

    
                                           # aback to Calendar

    
   print("

Back in ",__PACKAGE__,"...

");

    
   print("list = ",join( ,  ,@list),"

");

    
   amalgamation Fruit;                          # entering Fruit

    
   print("

Back in ",__PACKAGE__,"...

");

    
   print("main::p = ",$main::p,"

");

    
   print("Fruit::p = ",$Fruit::p,"

"); 

    
   print("list = ",join( ,  ,@list),"

");

    
   print("main::list = ",join( ,  ,@main::list),"

");

    
   print("Calendar::list = ",join( ,  ,@Calendar::list),"

");

    
   exit;