* Steven D'Aprano:
On Fri, 16 Apr 2010 08:48:03 -0700, Aahz wrote:
In article <4bb92850$0$8827$c3e8...@news.astraweb.com>, Steven D'Aprano
<st...@remove-this-cybersource.com.au> wrote:
Nevertheless, it is a common intuition that the list comp variable
should *not* be exposed outside of the list comp, and that the for-loop
variable should. Perhaps it makes no sense, but it is very common --
I've never heard of anyone being surprised that the for-loop variable is
exposed, but I've seen many people surprised by the fact that list-comps
do expose their loop variable.
I've definitely seen people surprised by the for-loop behavior.
What programming languages were they used to (if any)?
I don't know of any language that creates a new scope for loop variables,
but perhaps that's just my ignorance...
MRAB has mentioned Ada, let me mention C++ ...
<code language="C++">
#include <assert.h>
int main()
{
int const i = 42;
for( int i = 0; i < 10; ++i )
{
// blah blah
}
assert( i == 42 );
}
</code>
Java and C# take a slightly different approach where code analogous to the above
won't compile. But it's still a nested scope. E.g. ...
<code language="Java">
class App
{
static public void main( String[] args )
{
for( int i = 0; i < 10; ++i )
{
// blah blah
}
// Uncomment statement below to get compilation error:
//System.out.println( i );
}
}
</code>
So, yes, considering Ada, C++, Java and C# -- and so on. ;-)
Cheers & hth.,
- Alf
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