Le 28/06/2015 22:47, Anne Schilling a écrit :
Hi Nicolas B.,
Thank you for your explanations! It was a little difficult
to find this bug since in some cases it actually works
{{{
sage: positions=[1,2,3,4,5,6]
sage: for j in positions:
if is_even(j):
positions.remove(j)
:
sage:
Hi Nicolas B.,
Thank you for your explanations! It was a little difficult
to find this bug since in some cases it actually works
{{{
sage: positions=[1,2,3,4,5,6]
sage: for j in positions:
if is_even(j):
positions.remove(j)
:
sage: positions
[1, 3, 5]
}}}
{{{
sage: positions=[1,2,3
I'm surprised it's not raising an error as well because I knew of the error
that the dictionary raises that Simon mentioned having personally
encountered it in my code myself.
There is not a copy of i with its current value that build the current
> lambda each step, no. In fact, all lambda use
On Sun, Jun 28, 2015 at 12:05 PM, Nicolas Borie wrote:
> i is a free variable and exist in a single piece of memory...
Gods. This is worse than I thought...
The only reason why this doesn't happen for, say, "L = [2**i for i in
range(5)]", is that 2**i is eagerly evaluated, I guess?
> What about
Le 28/06/2015 11:42, Darij Grinberg a écrit :
On Sun, Jun 28, 2015 at 10:07 AM, Nicolas Borie wrote:
PS: The last entry of my collection of Python tricky codes was danger from
free variables : (MAKE A LIST OF FIRST POWER FUNCTION (1, X, X^2, X^3,
X^4))
L = [lambda x : x**i for i in range(5)]
On Sun, Jun 28, 2015 at 10:07 AM, Nicolas Borie wrote:
> PS: The last entry of my collection of Python tricky codes was danger from
> free variables : (MAKE A LIST OF FIRST POWER FUNCTION (1, X, X^2, X^3,
> X^4))
L = [lambda x : x**i for i in range(5)] # BAD
[L[j](2) for j in range(5)]
On Sun, Jun 28, 2015 at 10:07:43AM +0200, Nicolas Borie wrote:
> Le 28/06/2015 06:55, Anne Schilling a écrit :
> >Is this what I should expect from this code:
> >
> >sage: positions=[1,2,3,4,5,6]
> >sage: for j in positions:
> >: positions.remove(j)
> >:
> >sage: positions
> >[2, 4, 6]
Le 28/06/2015 06:55, Anne Schilling a écrit :
Hi!
Is this what I should expect from this code:
sage: positions=[1,2,3,4,5,6]
sage: for j in positions:
: positions.remove(j)
:
sage: positions
[2, 4, 6]
Wha this one will increase my collection of tricky examples... There
is a war
Hi!
Is this what I should expect from this code:
sage: positions=[1,2,3,4,5,6]
sage: for j in positions:
: positions.remove(j)
:
sage: positions
[2, 4, 6]
Shouldn't I expect the empty list at the end? Of course, I agree
the code is a little weird since it is running through a list
wh
