So, just to summarise the discussion:
There was some very mild support for readable pipelines, either using UFCS or
an alternative syntax, but the Pythonic way to make combinations of function
and method applications readable is to assign to variables over multiple lines.
Make the code read
Steven D'Aprano steve+comp.lang.pyt...@pearwood.info:
On Sun, 08 Jun 2014 18:56:47 +0300, Marko Rauhamaa wrote:
In fact, what's the point of having the duality?
x y == x.__lt__(y)
[...]
Consider x + y. What happens?
#1 First, Python checks whether y is an instance of a *subclass* of
On Monday, 9 June 2014 04:44:22 UTC+1, Chris Angelico wrote:
This could be solved, though, by having a completely different symbol
that means the thing on my left is actually the first positional
parameter in the function call on my right, such as in your example:
plus(1, 2) | divide(2)
On Mon, 09 Jun 2014 09:25:33 +0300, Marko Rauhamaa wrote:
In a word,
Python has predefined a handful of *generic functions/methods*,
That's nine words :-)
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Steven D'Aprano
http://import-that.dreamwidth.org/
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https://mail.python.org/mailman/listinfo/python-list
On Mon, Jun 9, 2014 at 7:09 PM, Steven D'Aprano
steve+comp.lang.pyt...@pearwood.info wrote:
On Mon, 09 Jun 2014 09:25:33 +0300, Marko Rauhamaa wrote:
In a word,
Python has predefined a handful of *generic functions/methods*,
That's nine words :-)
I'll explain in two words: We propose to
On Mon, 09 Jun 2014 19:13:40 +1000, Chris Angelico wrote:
On Mon, Jun 9, 2014 at 7:09 PM, Steven D'Aprano
steve+comp.lang.pyt...@pearwood.info wrote:
On Mon, 09 Jun 2014 09:25:33 +0300, Marko Rauhamaa wrote:
In a word,
Python has predefined a handful of *generic functions/methods*,
On Jun 8, 2014 9:56 PM, Steven D'Aprano
which means that hasattr (which is defined by
attempting to get the attribute and seeing if an exception is thrown)
has to return True.
Yes. And this is a problem why?
Earlier in this thread I pointed out that returning True creates problems
for
Thanks for the extensive feedback. Here's my thoughts on how to address these
issues.
On Saturday, 7 June 2014 20:20:48 UTC+1, Ian wrote:
It's a nice feature in a statically typed language, but I'm not sure
how well it would work in a language as dynamic as Python. There are
some
On Sunday, 8 June 2014 02:27:42 UTC+1, Gregory Ewing wrote:
Also it doesn't sit well with Python's one obvious
way to do it guideline, because it means there are
*two* equally obvious ways to call a function.
This provides a way to do something new (add class-optimized implementations
for
On Sunday, 8 June 2014 02:27:42 UTC+1, Gregory Ewing wrote:
Also it doesn't sit well with Python's one obvious
way to do it guideline, because it means there are
*two* equally obvious ways to call a function.
Actually, one of the best arguments against introducing UFCS is that Python
Hello,
On Sun, 8 Jun 2014 01:15:43 -0700 (PDT)
jongiddy jongi...@gmail.com wrote:
Thanks for the extensive feedback. Here's my thoughts on how to
address these issues.
On Saturday, 7 June 2014 20:20:48 UTC+1, Ian wrote:
It's a nice feature in a statically typed language, but I'm not
Hello,
On Sun, 8 Jun 2014 01:26:04 -0700 (PDT)
jongiddy jongi...@gmail.com wrote:
On Sunday, 8 June 2014 02:27:42 UTC+1, Gregory Ewing wrote:
Also it doesn't sit well with Python's one obvious
way to do it guideline, because it means there are
*two* equally obvious ways to call a
In article 1dd863ba-09e5-439b-8669-db65f3e99...@googlegroups.com,
jongiddy jongi...@gmail.com wrote:
On Sunday, 8 June 2014 02:27:42 UTC+1, Gregory Ewing wrote:
Also it doesn't sit well with Python's one obvious
way to do it guideline, because it means there are
*two* equally obvious
On Sunday, 8 June 2014 15:59:14 UTC+1, Roy Smith wrote:
Why? I assume a language which promoted the global namespace to be in
the attribute search path (which, as far as I can tell, is what we're
talking about here) would implement hasattr and raising AttributeError
in a consistent way.
Paul Sokolovsky pmis...@gmail.com:
Python already has that - like, len(x) calls x.__len__() if it's
defined
In fact, what's the point of having the duality?
len(x) == x.__len__()
x y == x.__lt__(y)
str(x) == x.__str__()
etc.
I suppose the principal reason is that people don't
On Sunday, 8 June 2014 13:06:08 UTC+1, Paul Sokolovsky wrote:
Getting x.foo() to call foo(x) is what's bigger problem, which has
serious performance and scoping confusion implications, as discussed in
other mails.
The performance hit will only occur when the attribute access is about to
On Sunday, 8 June 2014 17:24:56 UTC+1, jongiddy wrote:
# would work with UFCS
f.readlines().map(int).min(key=lambda n: n %
10).str().b64encode(b'?-').print()
Ooops - map is the wrong way round to support UFCS in this case. However, with
UFCS, I could fix this by changing it to smap, and
On Sun, Jun 8, 2014 at 9:56 AM, Marko Rauhamaa ma...@pacujo.net wrote:
Paul Sokolovsky pmis...@gmail.com:
Python already has that - like, len(x) calls x.__len__() if it's
defined
In fact, what's the point of having the duality?
len(x) == x.__len__()
x y == x.__lt__(y)
str(x)
Hello,
On Sun, 08 Jun 2014 18:56:47 +0300
Marko Rauhamaa ma...@pacujo.net wrote:
Paul Sokolovsky pmis...@gmail.com:
Python already has that - like, len(x) calls x.__len__() if it's
defined
In fact, what's the point of having the duality?
len(x) == x.__len__()
x y ==
On Mon, Jun 9, 2014 at 1:39 AM, jongiddy jongi...@gmail.com wrote:
e.g. I could define:
def squared(x):
return x * x
i = 3
i.squared() = 9
j = AClassThatImplements__mul__()
j.squared() = whatever j * j returns
but also:
class AnotherClass:
def __mul__(self, other):
On Sun, Jun 8, 2014 at 10:24 AM, jongiddy jongi...@gmail.com wrote:
A contrived example - which of these is easier to understand?
from base64 import b64encode
# works now
print(b64encode(str(min(map(int, f.readlines()), key=lambda n: n % 10)),
b'?-'))
# would work with UFCS
On Sun, Jun 8, 2014 at 2:15 AM, jongiddy jongi...@gmail.com wrote:
One problem with your untested code, the superclasses would need to be
checked before using UFCS, so the structure is:
try:
return super().__getattr__(attr)
except AttributeError:
# resolve using UFCS
And then if
On Sun, Jun 8, 2014 at 10:48 AM, Chris Angelico ros...@gmail.com wrote:
Except that it's even more complicated than that, because hasattr
wasn't defined in your module, so it has a different set of globals.
In fact, this would mean that hasattr would become quite useless.
hasattr is a builtin,
On Mon, Jun 9, 2014 at 2:24 AM, jongiddy jongi...@gmail.com wrote:
A contrived example - which of these is easier to understand?
from base64 import b64encode
# works now
print(b64encode(str(min(map(int, f.readlines()), key=lambda n: n % 10)),
b'?-'))
# would work with UFCS
On Mon, Jun 9, 2014 at 3:08 AM, Ian Kelly ian.g.ke...@gmail.com wrote:
On Sun, Jun 8, 2014 at 10:48 AM, Chris Angelico ros...@gmail.com wrote:
Except that it's even more complicated than that, because hasattr
wasn't defined in your module, so it has a different set of globals.
In fact, this
On Sun, Jun 8, 2014 at 11:13 AM, Chris Angelico ros...@gmail.com wrote:
On Mon, Jun 9, 2014 at 3:08 AM, Ian Kelly ian.g.ke...@gmail.com wrote:
On Sun, Jun 8, 2014 at 10:48 AM, Chris Angelico ros...@gmail.com wrote:
Except that it's even more complicated than that, because hasattr
wasn't
On Sunday, 8 June 2014 18:24:28 UTC+1, Ian wrote:
But that would all be done in getattr, so I don't think it affects
hasattr's implementation at all. Since hasattr doesn't push anything
onto the stack, getattr doesn't have to care whether it was called
directly from Python or indirectly
On Mon, 09 Jun 2014 03:10:03 +1000, Chris Angelico wrote:
[...]
Actually, this is something that I've run into sometimes. I can't think
of any Python examples, partly because Python tends to avoid unnecessary
method chaining, but the notion of data flow is a very clean one -
look at shell
On Mon, Jun 9, 2014 at 1:20 PM, Steven D'Aprano
steve+comp.lang.pyt...@pearwood.info wrote:
On Mon, 09 Jun 2014 03:10:03 +1000, Chris Angelico wrote:
[...]
Stdio.write_file(foo.png,Image.PNG.encode(Image.JPEG.decode(
Stdio.read_file(foo.jpg)).autocrop().rotate(0.5).grey()));
With UFCS, that
In article 53952807$0$29988$c3e8da3$54964...@news.astraweb.com,
Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote:
(Note that Forth is brilliant here, as it exposes the argument stack and
gives you a rich set of stack manipulation commands.)
As does PostScript (which, despite its
On Mon, 09 Jun 2014 02:48:13 +1000, Chris Angelico wrote:
class Circle:
def squared(self):
raise NotImplementedError(Proven impossible in 1882)
The trouble is that logically Circle does have a 'squared' attribute,
while 3 doesn't; and yet Python guarantees this:
On Sun, 08 Jun 2014 18:56:47 +0300, Marko Rauhamaa wrote:
Paul Sokolovsky pmis...@gmail.com:
Python already has that - like, len(x) calls x.__len__() if it's
defined
In fact, what's the point of having the duality?
len(x) == x.__len__()
x y == x.__lt__(y)
str(x) ==
On Mon, Jun 9, 2014 at 1:53 PM, Steven D'Aprano
steve+comp.lang.pyt...@pearwood.info wrote:
which means that hasattr (which is defined by
attempting to get the attribute and seeing if an exception is thrown)
has to return True.
Yes. And this is a problem why?
Obviously it would mean that
The language D has a feature called Uniform Function Call Syntax, which allows
instance methods to be resolved using function calls.
In Python terms, the call:
x.len()
would first check if 'x' has a method 'len', and would then look for a function
'len', passing 'x' as the first argument.
On Sat, Jun 7, 2014 at 12:45 AM, jongiddy jongi...@gmail.com wrote:
The language D has a feature called Uniform Function Call Syntax, which
allows instance methods to be resolved using function calls.
In Python terms, the call:
x.len()
would first check if 'x' has a method 'len', and
Ian Kelly wrote:
It's a nice feature in a statically typed language, but I'm not sure
how well it would work in a language as dynamic as Python.
Also it doesn't sit well with Python's one obvious
way to do it guideline, because it means there are
*two* equally obvious ways to call a function.
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