Pythonic Discoveries, Part 2

While working on the feed parsing program, I wanted to display a numbered list. In C++, I would have used an incrementing variable and thought nothing of it. But I found this a little more complicated in Python. When I tried to simply set a variable and then display it along with an item in the list I was iterating through, I got an error that an int and a string cannot be concatenated. So I ended up doing it thus:

entrylist = []
for entry in current.entries:
 entrylist.append(entry.title)
bullet = 1
for x in entrylist:
  print str(bullet) + "- " + x
  bullet+=1

I don't know if this was a bad hack, and if there is an easier way to do this, but it worked. It seem interesting that an increment operator is not built into Python.\

Pythonic discoveries, Part 1

The "item1.function(variable)" form in Python was confusing me, until I got something to work in the interpreter. I made a list:

>>> countries = ['USA', 'Russia', 'Cuba', 'Iceland', 'Greenland', 'Atlantis'])

and wanted to add 'France' to it. Trying "append('France')" did not work, as the append() function did not know where to act. However, "countries.append('France')" did work. I realized I had been taking the "x.y" notation as something more complex than it actually is. It can more easily understood after thinking about List Comprehension. List Comprehension takes an expression and applies a for conditional within it, followed by zero or more for and if conditionals. Thus in:

>>> num = [2, 4, 6]
>>> [3*x for x in num]
[6, 12, 18]
>>> [3*x for x in num if x > 3]
[12, 18]

the expression "3*x" is applied to each term x in the list "num".

When something is imported, say a module called "fruit", then one can say "import fruit", and "fruit.peel()" (assuming that peel was defined in "fruit"), the same x.y() form. The "x.y" means: "do, or look for, y in x, or in the context of x."