On 27/10/2016 19:09, BartC wrote:
On 27/10/2016 17:13, Steve D'Aprano wrote:
On Fri, 28 Oct 2016 12:13 am, BartC wrote:
print "Enter 3 numbers: "
readln a,b,c
How is the interpreter supposed to know that a, b, c are numbers? What
sort
of numbers? 16-bit integers, 80-bit floats, Bignums, complex,
Fractions, or
something else?
But in a dynamically typed language, the compiler has no idea what you
expect a, b and c to be. So it returns text, and you can convert it
yourself.
I notice that when it comes to reading command-line arguments, then
Python's sys.argv presents them as a list, not one long string.
And the list is just a series of strings, so needing to know whether any
parameter was a number or whatever obviously wasn't a problem. It just
makes each item into a string (actually that might be a better default
than mine).
This is a very similar issue to reading items from a line of user input.
So why doesn't sys.argv just return a single string if a line is so easy
to parse?
(That's exactly what Windows' WinMain() function does - optional entry
point for executables under Windows. But C's main() entry point chops
the command line up into separate strings like Python.
Also - this might some bearing on why Python does it that way - under
Linux, a parameter such as *.py is replaced by the names of ALL the
files that end in .py. (I was rather astonished when I find out. But
I've recently had to deal with a directory containing 3,400,000 files so
having a single "*" converted into 3.4 million filenames would be
unwelcome.))
--
Bartc
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