[Tutor] Comparative code questions: Python vs. Rebol

[Jeff Shannon]

Tim Johnson wrote:

>Now here is a more complex example:
>Dynamically compose a series of functions such that
># python 
>  print H3("This an html header of level 3")
>  >>> "<H3>This is an html header of level 3</H3>"
>

Others have shown how you can make Python do what you ask, here. 
 Instead of repeating that, I'll show you a way to achieve much the same 
ends, but in a more Pythonic way -- something that I think makes it 
easier to read, understand, and thus mantain.

Instead of having a series of very similar functions that make 
almost-equivalent modifications to a string, it's much simpler to have a 
*single* function that takes a parameter to indicate which of several 
modifications to make.

 >>> def HtmlHeader(level, text):
...     return "<H%d>%s</H%d>" % (level, text, level)
...
 >>> HtmlHeader(1, "This is level 1")
'<H1>This is level 1</H1>'
 >>> HtmlHeader(3, "This is level 3")
'<H3>This is level 3</H3>'
 >>> HtmlHeader(6, "This is level 6")
'<H6>This is level 6</H6>'
 >>>

The % operator, in this context, will make substitutions in the string 
in a manner similar to C's printf() formatting.  By doing it this way, 
we have only one function to keep track of, instead of six.  This is 
easier on both the writer of the library (this is simpler than the 
dynamic composition), and on the user of the library who has five less 
functions to keep track of.  (In production code, I'd insert some sanity 
checking to ensure, for example, that the level was an integer value 
between one and six [inclusive], but that seems overkill for example code.)

Jeff Shannon
Technician/Programmer
Credit International