On 06/05/13 12:37, Brian van den Broek wrote:
On 5 May 2013 22:10, boB Stepp <[email protected]> wrote:
On Sun, May 5, 2013 at 7:54 PM, Steven D'Aprano <[email protected]>
wrote:
<snip>
So my main question is there a truly clean, cross-platform solution to
the clear screen dilemma? If my online searching is accurate, then the
answer appears to be no, unless one wants to print many blank lines.
Your googling is accurate. There is no clean, cross-platform solution,
not
even for the "main three" (Linux/Unix, Windows, Mac), let alone minority
and
legacy platforms, other implementations, etc.
So it appears that the only way to cover the various possibilities is
to query for the platform being used and then apply the correct
statement for that platform. And it still would not work for the point
noted above. Could be a lot of effort for little gain!
Try:
def pragmatic_as_if_clear():
print '\n' * 100
which isn't too far off of what clear does in bash.
Not in the version of bash I am using in an xterm window. (To be precise,
Konsole under KDE 3.)
If I start a bash session, and then do something "large" like print a file
listing, the prompt ends up right at the bottom of the screen. If I then call clear, the
visible area of the screen is cleared, the prompt ends up at the top of the screen, but
if I scroll back using the scroll bar, I can see the previous output immediately before
the clear command, without 100 blank lines separating them.
A second question is that one person had as the answer to use:
os.system( [ 'clear', 'cls' ][ os.name == 'nt' ] )
I don't understand this syntax. The writer said that if one
understands what this is doing, then the method is more generally
useful. Would someone explain how this works? And hopefully it will
become apparent to me how this is more generally useful?
<snip>
terms when I saw the first pair of brackets, so it did not occur to me
to see the second set of brackets as indexing.
boB
Steven explained it. I'd point out that wiser snake charmers than I
discouraged me (some on this list) from using it from the position that it
was too clever. I've done so from time to time anyway; there is a momentary
jolt when reading the code months later.
I don't know who they were, I certainly hope they didn't include me.
The list[index] trick shown above is clever, but it shouldn't be too clever. It
used to be one of the standard ways of getting a one-line ternary expression in
Python. Of course, these days we have proper ternary operator `value if flag
else other`, but it's still a perfectly reasonable thing to do, no weirder and
much more concise than something like this:
commands = {'windows': 'clr', 'other': 'clear'}
if os.name == 'nt':
system = 'windows'
else:
system = 'other'
os.system(commands[system])
--
Steven
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