How to set subobject properties

[David McFarlane]

John,m

At 12/1/2011 07:18 AM Thursday, you wrote:
>I want to set subobject properties on the fly rather than hard code
>them in the properties box. (eg set an image's size and position on a
>slide object)
>
>I suppose I could define extra attributes in the list and set their
>values with setattrib() and then in the properties box for the image
>refer to [width] etc but I'd like to use this as an opportunity to
>learn a bit more.

Well, this is already the correct solution, for at least three reasons...

(1) Using attribute references documents your parameter values in the 
logged data file.  Presumably, you want those values logged with the 
data anyway.  In that case, you will already use c.SetAttrib just to 
log the values (BTW, you do *not* need to create attributes in a List 
before you set them with c.SetAttrib, just go right ahead and use 
c.SetAttrib in inline code), and as long as your program does that 
already, you might as well just use those as an attribute references 
(e.g., "[width]") to manipulate sub-object properties.

(2) Using attribute references better documents what happens within 
your sub-objects.  If you start monkeying with sub-object properties 
directly with code, then nothing in the sub-object itself will 
reflect that, which could be misleading to anyone who later looks at 
your program (including you two weeks from now).  It is poor 
programming practice to obfuscate program behavior like that.  If you 
use an attribute reference in your sub-object property, then that 
alerts the reader that that value is subject to change, and to look 
for the definition of the attribute somewhere else in the program.

(3) It is usually easier and cleaner to manipulate sub-object 
properties by means of attribute references rather than directly.  In 
fact, I would hazard that the designers of E-Prime specifically added 
this facility as a convenience to users, so to circumvent that rather 
destroys the purpose of the facility -- it would be like getting an 
underground garden sprinkler system installed, and then asking, 
"Where is the garden hose, and how do I hook it up to the 
spigot?"  Remember, for better or worse, this is E-Prime, *not* pure 
VBA (much less C or C++).


Nevertheless, you might have a legitimate reason to manipulate 
sub-objects directly in code, or you might just be determined to do 
things the wrong way.  In that case...

>The Reference manual lists loads of funciton s eg CSlideImage but I
>can't find any documentation any where that explains what they do or
>how to use them.

Contrary to what you may expect based on the title, the "Reference 
Guide" is *not* the E-Prime technical reference.  You will find what 
counts as a technical reference in the E-Basic Help facility, which 
you may access from the Help menu in E-Studio, or from the E-Prime 
menu off the Windows Start menu.  Slide sub-object topics (e.g., 
SlideText) there will include examples of E-Basic code.  Bear in 
mind, however, that the E-Prime documentation is incomplete, and 
sometimes misleading or just plain wrong, so keep your wits about you 
and test everything for yourself.


>Can anyone help/point me in the right direction?

See also my two essays at 
<http://groups.google.com/group/e-prime/browse_thread/thread/5425e03968cab428>http://groups.google.com/group/e-prime/browse_thread/thread/5425e03968cab428 
and 
<http://groups.google.com/group/e-prime/browse_thread/thread/b0ce54870b723fc3>http://groups.google.com/group/e-prime/browse_thread/thread/b0ce54870b723fc3 
.

-- David McFarlane

-- 
You received this message because you are subscribed to the Google Groups "E-Prime" group.
To post to this group, send email to e-prime at googlegroups.com.
To unsubscribe from this group, send email to e-prime+unsubscribe at googlegroups.com.
For more options, visit this group at http://groups.google.com/group/e-prime?hl=en.