will not compile

kevind0718 has asked for the wisdom of the Perl Monks concerning the following question:

hello monks:

I am try to create a simple subroutine. Basically copied the example from Learning Perl pg 59. The error message is:
Can't modify constant item in list assignment at loadBofATradesB.pl line 156, near "@_;" This is my subroutine

sub fieldString {
  my($strIn, $typeIn);    #this is line 156
  ($strIn,  typeIn)  =  @_;
    $strIn = trim(strIn);
    
  
  $rtnVal = undef;
  
  if ( length($strIn) ==  0 ) {
    $rtnVal = 'NULL'; 
  
  }
  else  {
    if (typeIn == 'N')  {
       $retVal = $strIn;   
     }  
     else  {
        $retVal = "'$strIn'";   
     
     }  
  
  }
  
  $retVal;

}


 
# Perl trim function to remove whitespace from the start and end of th
+e string
sub trim($)
{
    my $string = shift;
    $string =~ s/^\s+//;
    $string =~ s/\s+$//;
    return $string;
}
[download]

I do not understand my mistake.

kd

Comment on will not compile Download Code

Replies are listed 'Best First'.
Re: will not compile by ikegami (Patriarch) on Sep 18, 2007 at 16:43 UTC
Other bugs: `"'$strIn'"` is critically flawed. (What if `$strIn` contains a quote...) `$rtnVal` and `$retVal` are never declared. Aren't `$rtnVal` and `$retVal` suppose to be the same variable? You're using `==` for lexical comparison. Use `eq` for that. `use strict;` is probably missing Unrequired use of a prototype. Prototypes are best avoided, so `sub trim($) { ... }` should be `sub trim { ... }`. Sounds like you should be using placeholders (e.g. `SELECT * FROM table WHERE field = ?`) instead of writing your own quoting function.	[reply] [d/l] [select]
Re^2: will not compile by kevind0718 (Scribe) on Sep 18, 2007 at 17:30 UTC
many thanks to all of you after a break I see those silly mistakes. Maybe I need to take a walk or better yet a nap kd	[reply]
Re: will not compile by toolic (Bishop) on Sep 18, 2007 at 16:26 UTC
I think it's a typo: use `$typeIn` instead of `typeIn` everywhere.	[reply] [d/l] [select]
Re: will not compile by ikegami (Patriarch) on Sep 18, 2007 at 16:36 UTC
If made the mistake of not using `use strict;`, you won't see the much more revealing message `Bareword "typeIn" not allowed while "strict subs" in use.` [download]	[reply] [d/l] [select]