comment on

Honorable Monks,

After this discussion -> Re^6: while(){}continue{}; Useful? (Consistent!), I'm trying to understand the extended functionality of the new Given/When compared to the old workaround with For/Next.

As far as I understand,

In given/when I have to write a continue (statement not block!) where I omit the next statement. I need to "invert" the fall through.

In given/when I lose the continue-block which is always executed.

The when has an automatically built in smart match ~~. Nice ...but how can I take profit from this smart match if the parameter passed into given can only be a scalar?

Maybe I missed something, please see the example code to understand what I mean:

CODE:

use feature "switch";
 
 
$,=$\="\t";
@test=qw/abc def abcdef nnn/;

print "\n\n=== Given/When";
for (@test){
  print "\nGIVEN($_):";
  given($_) {
    when (/abc/) { print "abc";continue }
    when (/def/) { print "def" }
    when (/xyz/) { print "xyz" }
    default { print "default" }
  }
}
 
 
print "\n\n=== For";
for (@test){
  for ($_){
    print "\nFOR($_):";
    if (/abc/) { print "abc"}
    if (/def/) { print "def" ;next}
    if (/xyz/) { print "xyz" ;next}
    print "default";
  }
}
 
print "\n\n=== For/Continue";
# "simplifying" the former with post-ifs and &&
# using continue-block
my @res;
for (@test){
  push (@res, "abc")         if (/abc/);
  push (@res, "def") && next if (/def/);
  push (@res, "xyz") && next if (/xyz/);
  push (@res, "default");
} continue {
  print "\nFOR/CONT($_):",@res;
  @res=();
}
 
 
print "\n\n === When smartmatch\n";
 
print "\n= GIVEN(\@test):\n";
given(@test) {
  print "whats tested is:",$_;
  when (/abc/) { print "abc";continue }
  when (/def/) { print "def" }
  when (/xyz/) { print "xyz" }
  default { print "default" }
}
 
print "\n= GIVEN(\\\@test):\n";
# does when act differently when a arr_reff is passed?
given(\@test) {
   print "whats tested is:",$_;
  when (/abc/) { print "abc";continue }
  when (/def/) { print "def" }
  when (/xyz/) { print "xyz" }
  default { print "default" }
}
 
# whats the point of implicit smartmatch if only scalars can be testet
+??? smartmatchingan array is different
print "\nBUT: def ~~ \@test!" if @test ~~ /def/;
[download]

OUTPUT:

=== Given/When    
GIVEN(abc):    abc    default    
GIVEN(def):    def    
GIVEN(abcdef):    abc    def    
GIVEN(nnn):    default    
 
=== For    
FOR(abc):    abc    default    
FOR(def):    def    
FOR(abcdef):    abc    def    
FOR(nnn):    default    
 
=== For/Continue    
FOR/CONT(abc):    abc    default    
FOR/CONT(def):    def    
FOR/CONT(abcdef):    abc    def    
FOR/CONT(nnn):    default    
 
 === When smartmatch
    
= GIVEN(@test):
    whats tested is:    ARRAY(0x8a08a38)    default    
= GIVEN(\@test):
    whats tested is:    ARRAY(0x8a08a38)    default    
BUT: def ~~ @test!
[download]

Cheers Rolf

UPDATE: extended given(Array) and given(Array_ref)

Since given accepts arrays and automatically passes the ref without when reacting accordingly, I suppose it's a BUG!

In reply to Understanding the benefit of Given/When ... by LanX

Are you posting in the right place? Check out Where do I post X? to know for sure.
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
Want more info? How to link or How to display code and escape characters are good places to start.


There's more than one way to do things
	PerlMonks