Teaching Programming
in [Python]
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From: superpollo on 4 May 2010 13:56 James Mills ha scritto: > On Tue, May 4, 2010 at 9:56 PM, superpollo <utente(a)esempio.net> wrote: >> of course! *but* if i must generate on-the-fly python code that defines a >> function i am back again to the problem: > > One-liner: > > $ python > Python 2.6.5 (r265:79063, Apr 27 2010, 18:26:49) > [GCC 4.4.1 (CRUX)] on linux2 > Type "help", "copyright", "credits" or "license" for more information. >>>> a, b = 2, 3 >>>> print a + b if a > b else a**b - b**2 > -1 >>>> a, b = 3, 2 >>>> print a + b if a > b else a**b - b**2 > 5 > > --James what if i want an elif clause?
From: superpollo on 4 May 2010 14:16 superpollo ha scritto: > James Mills ha scritto: >> On Tue, May 4, 2010 at 9:56 PM, superpollo <utente(a)esempio.net> wrote: >>> of course! *but* if i must generate on-the-fly python code that >>> defines a >>> function i am back again to the problem: >> >> One-liner: >> >> $ python >> Python 2.6.5 (r265:79063, Apr 27 2010, 18:26:49) >> [GCC 4.4.1 (CRUX)] on linux2 >> Type "help", "copyright", "credits" or "license" for more information. >>>>> a, b = 2, 3 >>>>> print a + b if a > b else a**b - b**2 >> -1 >>>>> a, b = 3, 2 >>>>> print a + b if a > b else a**b - b**2 >> 5 >> >> --James > > what if i want an elif clause? > my first try obviously falied: >>> print a + b if a > b elif a=b "WOW" else a**b - b**2 File "<stdin>", line 1 print a + b if a > b elif a=b "WOW" else a**b - b**2 ^ SyntaxError: invalid syntax
From: Terry Reedy on 4 May 2010 14:35 On 5/4/2010 1:44 PM, Dennis Lee Bieber wrote: > On Tue, 04 May 2010 12:06:10 -0400, Terry Reedy<tjreedy(a)udel.edu> > declaimed the following in gmane.comp.python.general: > >> Speak for yourself, please. For two decades before I met Python, I >> indented code nicely whenever it was allowed. That option was one of the >> great advancements of Fortran77 over FortranIV. Coming from C, I was >> immediately glad to be done with those darn braces. >> > What kept you from indenting FORTRAN-IV? There was a several year gap with learning of 'structured programming' in between. Perhaps ignorance of both the possibility (no one did it, that I know of) and desirability. Glass screens made consistent indentation a lot easier that with cards and teletypes. The new structured block constructs made indentation more useful, too.
From: superpollo on 4 May 2010 14:35 superpollo ha scritto: > superpollo ha scritto: >> James Mills ha scritto: >>> On Tue, May 4, 2010 at 9:56 PM, superpollo <utente(a)esempio.net> wrote: >>>> of course! *but* if i must generate on-the-fly python code that >>>> defines a >>>> function i am back again to the problem: >>> >>> One-liner: >>> >>> $ python >>> Python 2.6.5 (r265:79063, Apr 27 2010, 18:26:49) >>> [GCC 4.4.1 (CRUX)] on linux2 >>> Type "help", "copyright", "credits" or "license" for more information. >>>>>> a, b = 2, 3 >>>>>> print a + b if a > b else a**b - b**2 >>> -1 >>>>>> a, b = 3, 2 >>>>>> print a + b if a > b else a**b - b**2 >>> 5 >>> >>> --James >> >> what if i want an elif clause? >> > > my first try obviously falied: > > >>> print a + b if a > b elif a=b "WOW" else a**b - b**2 > File "<stdin>", line 1 > print a + b if a > b elif a=b "WOW" else a**b - b**2 > ^ > SyntaxError: invalid syntax > ok i got it: >>> a,b=2,3 >>> print a + b if a > b else "WOW" if a < b else a**b - b**2 WOW >>>
From: Benjamin Kaplan on 4 May 2010 14:44
On Tue, May 4, 2010 at 2:16 PM, superpollo <utente(a)esempio.net> wrote: > superpollo ha scritto: >> >> James Mills ha scritto: >>> >>> On Tue, May 4, 2010 at 9:56 PM, superpollo <utente(a)esempio.net> wrote: >>>> >>>> of course! *but* if i must generate on-the-fly python code that defines >>>> a >>>> function i am back again to the problem: >>> >>> One-liner: >>> >>> $ python >>> Python 2.6.5 (r265:79063, Apr 27 2010, 18:26:49) >>> [GCC 4.4.1 (CRUX)] on linux2 >>> Type "help", "copyright", "credits" or "license" for more information. >>>>>> >>>>>> a, b = 2, 3 >>>>>> print a + b if a > b else a**b - b**2 >>> >>> -1 >>>>>> >>>>>> a, b = 3, 2 >>>>>> print a + b if a > b else a**b - b**2 >>> >>> 5 >>> >>> --James >> >> what if i want an elif clause? >> > > my first try obviously falied: > >>>> print a + b if a > b elif a=b "WOW" else a**b - b**2 > File "<stdin>", line 1 > print a + b if a > b elif a=b "WOW" else a**b - b**2 > ^ > SyntaxError: invalid syntax That's because this technically isn't an if statement. It's the ternary conditional expression. If you want multiple conditions, you have to repeat the expression print a+b if a > b else "WOW" if a==b else a**b - b**2 > > -- > http://mail.python.org/mailman/listinfo/python-list > |