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How to build the => in a statement? ds456 04-24-2008
Posted by ds456 on April 24, 2008, 6:50 pm
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 I am trying to build Perl/TK components from scratch inside another TK
program. I am stumped on how to represent the " => " in a statement
inside a variable.

This is a normal statement and works ...
        $xw->Button(-text => "This is text")->place(-x => 1, -y => 1);

So does this...
        $attrib = '-text';
        $value = 'This is text'
        $xw->Button($attrib => $value)->place(-x => 1, -y => 1);

Since the "equal/greater than" is a signal to the compiler rather than a
literal string, this does not...
        $string = "-title => 'This is text'";
        $xw->Button($string)->place(-x => 1, -y => 1);

I am trying to programatically build the inside of the parens and add
various options based on user input, but can't figure out how to represent
the => .

Suggestions anybody. Or is the above as clear as mud?

DS

Posted by John W. Krahn on April 24, 2008, 7:08 pm
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 ds456 wrote:
> I am trying to build Perl/TK components from scratch inside another TK
> program. I am stumped on how to represent the " => " in a statement
> inside a variable.
>
> This is a normal statement and works ...
>         $xw->Button(-text => "This is text")->place(-x => 1, -y => 1);
>
> So does this...
>         $attrib = '-text';
>         $value = 'This is text'
>         $xw->Button($attrib => $value)->place(-x => 1, -y => 1);
>
> Since the "equal/greater than" is a signal to the compiler rather than a
> literal string, this does not...
>         $string = "-title => 'This is text'";
>         $xw->Button($string)->place(-x => 1, -y => 1);
>
> I am trying to programatically build the inside of the parens and add
> various options based on user input, but can't figure out how to represent
> the => .
>
> Suggestions anybody. Or is the above as clear as mud?

Assuming that the attributes are unique you could use a hash:

my %attributes = ( -title => 'This is text' );

$xw->Button( %attributes )->place( -x => 1, -y => 1 );


Or in either case you could use an array:

my @attributes = ( -title => 'This is text' );

$xw->Button( @attributes )->place( -x => 1, -y => 1 );



John
--
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order. -- Larry Wall

Posted by ds456 on April 24, 2008, 8:10 pm
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> Or in either case you could use an array:
>
> my @attributes = ( -title => 'This is text' );
>
> $xw->Button( @attributes )->place( -x => 1, -y => 1 );
>
>
>
> John

Thanks for the reply John, but that doesn't work for me either. Below is
the actual code and part of the error message.


my @attributes = ( -title => 'This is text');
$xw->Button( @attributes )->place(-x => 1, -y => 1);

#Tk::Error: unknown option "-title" at /usr/lib/perl5/Tk/Widget.pm line
205.

Posted by ds456 on April 24, 2008, 8:13 pm
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O
> This is a red herring. What you need to do is to pass the correct
> arguments to the method.
>
> So, if for some reason, you don't have the $attrib and $value separately
> but embedded in a string of the form
>
> "attrib => whatever"
>
> you need to extract those two values and pass them as arguments to the
> method call.


Thanks for the reply Sinan, but I didn't make my question clear.

I have the attributes and values already separate, either in an array or
hash.

Example

$widget = Button;
-text 'OK'
-width 10
-state 'disabled'
-command '\&okcommand'

and so forth.

I don't want to hard code those widget options since there may be from 1
to 20 or so of them, depending on what kind of widget it is and what the
user wants.

Rather I want to feed the attributes and values to a routine that will
build the widget with whatever number options I pass to it.

Sort of like so...

        foreach $key (keys @%hash) {
                #Some code to build a string from the current hash key...
        }
        #Finally, a string is built that looks good...
        $string = "-text => 'OK',
        -width => 10, -state => 'disabled', -command => '\&okcommand'";
        
        $xw->$widget($string)->pack();

        But this doesn't work because the => operator can't be imbedded in the
        string.
        
        
To put it logically, rather than in code, I am trying to do this...

        $wx->$widget(
                foreach $key (keys %hash){
                        $key => $hash ,
                }
        )->place(-x => somexpos, -y => someypos);

Thanks again

DS

Posted by John Bokma on April 25, 2008, 1:39 pm
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If you morph again to keep trolling here, I'll contact your usenet
provider.

If you disagree with how some people post here, show them a better
example instead of trolling (again) this group. Sinan (IIRC) made a
valid point recently on people posting here:

* those who can help (even though it's not always in a nice way, you'll
get in the end help, and for free, even if you're too lazy to read
a book and/or documentation),
* those who can't just troll.

Based on your earlier trolls I would say that "can't" must be the story of
your life.

*ploink*

--
John

http://johnbokma.com/perl/

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