[reportlab-users] get methods for properties

Randall Smith reportlab-users@reportlab.com
Fri, 11 Jun 2004 13:19:28 -0500

Robin Becker wrote:
> Randall Smith wrote:
>> I'm new to reportlab.  I've been playing with it and looking at the 
>> source.  I like the design, especially the templates.  Thank you for 
>> opening it to the public; I hope you get useful feedback.
>> My comment is about getting properties.  Maybe I missed it, but I 
>> don't see a clean way to grab some useful properties.  For example, 
>> line width.  I wrote a flowable to draw a horizontal line.  I want to 
>> set the line width and return it back to what it was before the 
>> flowable was created.  Because _lineWidth starts with a _, I'm 
>> guessing this is a semi-private variable and subject to change (not 
>> part of the API).  So shouldn't canvas have an API attribute or call 
>> like canvas.lineWidth or canvas.getLineWidth()?
>> Here is code below:
>> class HR(Flowable):
>>     def __init__(self, height):
>>         Flowable.__init__(self)
>>         self.height = height
>>     def __repr__(self):
>>         return "HR(t=%s)" % (self.height,)
>>     def draw(self):
>>         orig_linewidth = self.canv._lineWidth # my problem is here
>>         self.canv.setLineWidth(height)
>>         self.canv.line(0, 0, 100, 0)
>>         self.canv.setLineWidth(orig_linewidth)
>> Randall
> .....
> I don't thinks there's anything wrong with reading _lineWidth and 
> friends, but the _ indicates it shouldn't be set. In modern Python we 
> could use a property to allow reading and writing with the appropriate 
> methods called on the underlying _ value.
> On the other hand the platypus/flowables framework allows you to make 
> any changes you like in your draw method. Each call to a draw method is 
> surrounded by a save & restore so you can feel free to do what you like 
> to the canvas inside. That means you don't need to save the linewitdh 
> yourself.

Thanks. I looked myself and found in the class Flowables, the drawOn 
method calls saveState and restoreState around draw.

I have a few more newbie questions, but I'll start a new post since its 
a new topic.