Re: What's the rationale for b"..." in this example?
On Wed, May 16, 2018 at 9:02 AM, Skip Montanaro wrote: >> Personally, I never use the str(..., encoding="...") notation; I prefer > to use the >> .decode() method of the bytes object. > > Thanks. And thanks for the other responses. I obviously didn't have my > thinking cap on this morning. (It was too late in the morning to plead lack > of coffee.) You plead lack of coffee until you plead caffeine overdose. That's the way of things. :) ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: What's the rationale for b"..." in this example?
> Personally, I never use the str(..., encoding="...") notation; I prefer to use the > .decode() method of the bytes object. Thanks. And thanks for the other responses. I obviously didn't have my thinking cap on this morning. (It was too late in the morning to plead lack of coffee.) Skip -- https://mail.python.org/mailman/listinfo/python-list
Re: What's the rationale for b"..." in this example?
On Wed, May 16, 2018 at 1:14 AM, Skip Montanaro
wrote:
> Consider this:
>
bytes("abc", encoding="utf-8")
> b'abc'
>
> Looks reasonable. Then consider this:
>
str(bytes("abc", encoding="utf-8"))
> "b'abc'"
>
> Why is the b'...' bit still there? I suppose it's because I didn't tell it
> explicitly how to decode the bytes object, as when I do, I get the expected
> result:
>
str(bytes("abc", encoding="utf-8"), encoding="utf-8")
> 'abc'
>
> Coming from a still largely Python 2 perspective, did all attempts to apply
> default encodings disappear in Python 3?
It's there for the same reason as the square brackets here:
>>> str(list('abc'))
"['a', 'b', 'c']"
Calling str() on arbitrary objects returns a printable string; and in
Py3, there's simply nothing special about bytes. Personally, I never
use the str(..., encoding="...") notation; I prefer to use the
.decode() method of the bytes object.
ChrisA
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Re: What's the rationale for b"..." in this example?
15.05.18 18:14, Skip Montanaro пише:
Consider this:
bytes("abc", encoding="utf-8")
b'abc'
Looks reasonable. Then consider this:
str(bytes("abc", encoding="utf-8"))
"b'abc'"
Why is the b'...' bit still there? I suppose it's because I didn't tell it
explicitly how to decode the bytes object, as when I do, I get the expected
result:
str(bytes("abc", encoding="utf-8"), encoding="utf-8")
'abc'
str() without 'encoding' and 'errors' calls __str__ which falls back to
__repr__ by default.
bytes.__str__ falls back to bytes.__repr__, this makes errors of mixing
bytes and strings more obvious. If run Python with the -b option, it
will emit a BytesWarning first. If run it with -bb, it will become an error.
You can receive many interesting warning when run Python 2 with options
-b and -3. Getting rid of these warnings will help with porting to
Python 3 and may fix real bugs.
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Re: What's the rationale for b"..." in this example?
Skip Montanaro writes:
> Consider this:
>
> >>> bytes("abc", encoding="utf-8")
> b'abc'
>
> Looks reasonable. Then consider this:
>
> >>> str(bytes("abc", encoding="utf-8"))
> "b'abc'"
>
> Why is the b'...' bit still there?
Because the bytes object is asked for a text representation of itself,
and the text value ‘b'abc'’ is what it returned.
> I suppose it's because I didn't tell it explicitly how to decode the
> bytes object, as when I do, I get the expected result:
>
> >>> str(bytes("abc", encoding="utf-8"), encoding="utf-8")
> 'abc'
Yes.
> Coming from a still largely Python 2 perspective, did all attempts to
> apply default encodings disappear in Python 3?
To the extent I understand that question, the answer is no.
Rather, the ‘bytes’ and ‘str’ types are now entirely incompatible, and
implicit conversions are never done between them. Any conversions
between them must be explicit.
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`\ responsibility better than you do.” —Ralph Waldo Emerson |
_o__) |
Ben Finney
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Re: What's the rationale for b"..." in this example?
On 05/15/2018 08:14 AM, Skip Montanaro wrote:
Consider this:
bytes("abc", encoding="utf-8")
b'abc'
Looks reasonable. Then consider this:
str(bytes("abc", encoding="utf-8"))
"b'abc'"
Why is the b'...' bit still there?
Because you are printing a bytes object, not a str.
I suppose it's because I didn't tell it
explicitly how to decode the bytes object, as when I do, I get the expected
result:
str(bytes("abc", encoding="utf-8"), encoding="utf-8")
'abc'
Coming from a still largely Python 2 perspective, did all attempts to apply
default encodings disappear in Python 3?
Pretty much, yup. There is no more guessing what encoding to use -- either specify it, or be made aware that you
printed a bytes object.
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~Ethan~
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What's the rationale for b"..." in this example?
Consider this:
>>> bytes("abc", encoding="utf-8")
b'abc'
Looks reasonable. Then consider this:
>>> str(bytes("abc", encoding="utf-8"))
"b'abc'"
Why is the b'...' bit still there? I suppose it's because I didn't tell it
explicitly how to decode the bytes object, as when I do, I get the expected
result:
>>> str(bytes("abc", encoding="utf-8"), encoding="utf-8")
'abc'
Coming from a still largely Python 2 perspective, did all attempts to apply
default encodings disappear in Python 3?
Skip
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