From: "Alex Martelli" <aleax@aleax.it>
> On Sunday 02 February 2003 11:04 pm, Samuele Pedroni wrote:
> > With Guido's 'do': [notice that count is rebindable in the thunk]
> >
> > class iterclose:
> > def __init__(self,iterwclose):
> > self.iter = iterwclose
> >
> > def __call__(self,thunk):
> > try:
> > for x in self.iter:
> > thunk(x)
> > finally:
> > self.iter.close()
> >
> > count = 0
> > do iterclose(open('blah.txt')): (line):
> > if line.find('Python') >=0:
> > count += 1
> > print line,
>
> OK -- I *don't* get that " (line):" part, and how calling thunk() in
> iterclose.__init__ binds/rebinds the local (?) variable line of the thunk.
> Looks like black magic to me. Guess I must just be a bit thick
> tonight -- sorry.
a thunk is like a Smalltalk block, a closure that can rebind the locals and can
get arguments ( (line): above) ),
and maybe non-local returns ( ^ in Smalltalk): in pseudo-python the above is:
count = 0
defClosureAllowingRebinding _thunk(line):
if line.find('Python') >=0:
count += 1
print line,
iterclose(open('blah.txt'))(_thunk)
> > class autoclose2:
> > def __init__(self,file):
> > self.file = file
> >
> > def __call__(self,thunk):
> > try:
> > thunk()
> > finally:
> > self.file.close()
> >
> > count = 0
> > myfile = open('blah.txt')
> > do autoclose2(open('blah.txt')):
> > for line in myfile:
> > if line.find('Python') >=0:
> > count += 1
> > print line,
>
> shouldn't that be "do autoclose2(myfile):" ? or is there some
> even-blacker magic in this "do" business that I don't get...?
>
yes, you're right.
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4