I just discovered the existence of an [Enum](https://docs.python.org/3/library/enum.html) base class in python and I&#39;m trying to imagine how it could be useful to me.

Let&#39;s say I define a traffic light status:

    from enum import Enum, auto
    
    class Signal(Enum):
        red = auto()
        green = auto()
        orange = auto()

Let&#39;s say I receive information from some subsystem in my program, in the form of a string representing a colour name, for instance `brain_detected_colour = &quot;red&quot;`.

**How do I compare this string to my traffic light signals?**

Obviously, `brain_detected_colour is Signal.red` is `False`, because `Signal.red` is not a string.

`Signal(brain_detected_colour) is Signal.red` fails with `ValueError: &#39;red&#39; is not a valid Signal`.

How to compare a string with a python enum?

Suppose you want to constrain a type variable to implement a certain interface. You might write something like so:

    from typing import TypeVar, Callable

    T = TypeVar(&#39;T&#39;, Callable)

    class Foo(Generic[T]):
        ...

    &gt;&gt; TypeError: A single constraint is not allowed

Why is Python unhappy about this use of type constraints? [PEP 484](https://www.python.org/dev/peps/pep-0484/#generics) and the [Python source code](https://github.com/python/typing/blob/master/src/typing.py#L511) are unhelpful in this regard.

Note: in my particular case I am interested in constraining a type variable to implement an abstract base class, but the principle is the same.

Why are single type constraints disallowed in Python?

I am moving my config from setup.py to setup.cfg and having issues setting up the `entry_points` parameter. At the moment I am using a hybrid approach which works, however, I would like to move the `entry_points` to setup.cfg.

From 

    def setup_package():
        setup(version=get_version(),
              entry_points={&#39;console_scripts&#39;:[&#39;app=my_package.app.run:cli&#39;],})

to

```cfg
[metadata]
name = my-package
description = my-package
license = unlicensed
long-description = README.md
platforms = any
classifiers =
  Programming Language :: Python

[options]
zip_safe = False
packages = my_package,  my_package.app
include_package_data = True
package_dir =
  = .
tests_require = pytest; pytest-cov

[entry_points]
console_scripts =
  my-package = my_package.app.run:cli
```

How to set up entry_points in setup.cfg

I want to connect to a remote PostgreSQL database through Python to do some basic data analysis. This database requires SSL (verify-ca), along with three files (which I have):

 - Server root certificate file
 - Client certificate file
 - Client key file

I have not been able to find a tutorial which describes how to make this connection with Python. 
Any help is appreciated.



How to connect to a remote PostgreSQL database through SSL with Python

I have been examining some of my string format options using the new f-string format.  I routinely need to unpack lists and other iterables of unknown length. Currently I use the following...

    &gt;&gt;&gt; a = [1, &#39;a&#39;, 3, &#39;b&#39;]
    &gt;&gt;&gt; (&quot;unpack a list: &quot; + &quot; {} &quot;*len(a)).format(*a)
    &#39;unpack a list:  1  a  3  b &#39;
This, albeit a bit cumbersome, does the job using pre-3.6 .format notation.
The new f-string format option is interesting given runtime string concatenation.  It is the replication of the number of {} that I am having problems with.  In my previous example, I simply created the necessary structure and unpacked within the .format() section.

Attempts to do this yielded one variant that worked, however:

### 1) Both curly brackets together doesn&#39;t unpack...

    &gt;&gt;&gt; &#39;unpack a list&#39;  f&#39; {{*a}}&#39;
    &#39;unpack a list {*a}&#39;

### 2) Adding spaces around the interior {} pair:

This works but leaves opening and closing braces {, } present:

    &gt;&gt;&gt; &#39;unpack a list&#39;  f&#39; { {*a} }&#39;
    &quot;unpack a list {1, 3, &#39;a&#39;, &#39;b&#39;}&quot;

### 2b) Concatenating the variants into one f-string

This made the look and syntax better, since the evaluation, apparently, is from left to right.  This, however, still left the enclosing curly brackets present:

    &gt;&gt;&gt; f&#39;unpack a list { {*a} }&#39;
    &quot;unpack a list {1, 3, &#39;a&#39;, &#39;b&#39;}&quot;

### 3) Tried automatic unpacking with just `{a}`
Perhaps, I was overthinking the whole procedure and hoping for some form of automatic unpacking.  This simply yielded the list representation with the curly brackets being replaced with `[]` :

    &gt;&gt;&gt; f&#39;unpack a list {a}&#39;
    &quot;unpack a list [1, &#39;a&#39;, 3, &#39;b&#39;]&quot;
    
What is required to suppress the curly brackets in variant (2) above, or must I keep using the existing `.format()` method?  I want to keep it simple and use the new capabilities offered by the f-string and not revert back beyond the python versions which pre-date what I am currently comfortable with.  I am beginning to suspect that f&#39;strings&#39; do not offer a complete coverage of what is offered by its `.format()` sibling.  I will leave it at that for now, since I haven&#39;t even ventured into the escape encoding and the inability to use \ in an f-string.  I have read the PEP and search widely, however, I feel I am missing the obvious or what I wish for is currently not possible.

EDIT several hours later:

### 4) Use subscripting to manually slice off the brackets: `str(a)[1:-2]`

I did find this variant which will serve for some cases that I need

    f&#39;unpack a list: {str(a)[1:-2]}&#39;
    &quot;unpack a list: 1, &#39;a&#39;, 3, &#39;b&quot;

But the slicing is little more than a convenience and still leaves the string quotes around the resultant.

### 5)  and the final solution from @SenhorLucas

     a = np.arange(10)
    
    print(f&quot;{*a,}&quot;)
    (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)

Unpacking with trailing comma.

f-string syntax for unpacking a list with brace suppression

I am trying to run a module from the console. The structure of my directory is this:

[![enter image description here][1]][1]

I am trying to run the module `p_03_using_bisection_search.py`, from the `problem_set_02` directory using:

    $ python3 p_03_using_bisection_search.py

The code inside `p_03_using_bisection_search.py`is:

    __author__ = &#39;m&#39;
    
    
    from .p_02_paying_debt_off_in_a_year import compute_balance_after
    
    
    def compute_bounds(balance: float,
                       annual_interest_rate: float) -&gt; (float, float):

        # there is code here, but I have omitted it to save space
        pass
    
    
    def compute_lowest_payment(balance: float,
                               annual_interest_rate: float) -&gt; float:

        # there is code here, but I have omitted it to save space
        pass    
    
    def main():
        balance = eval(input(&#39;Enter the initial balance: &#39;))
        annual_interest_rate = eval(input(&#39;Enter the annual interest rate: &#39;))
    
        lowest_payment = compute_lowest_payment(balance, annual_interest_rate)
        print(&#39;Lowest Payment: &#39; + str(lowest_payment))
    
    
    if __name__ == &#39;__main__&#39;:
        main()

I am importing a function that is in `p_02_paying_debt_off_in_a_year.py` which code is:

    __author__ = &#39;m&#39;
    
    
    def compute_balance(balance: float,
                        fixed_payment: float,
                        annual_interest_rate: float) -&gt; float:

        # this is code that has been omitted
        pass
    
    
    def compute_balance_after(balance: float,
                              fixed_payment: float,
                              annual_interest_rate: float,
                              months: int=12) -&gt; float:

        # Omitted code
        pass
    
    
    def compute_fixed_monthly_payment(balance: float,
                                      annual_interest_rate: float) -&gt; float:

        # omitted code
        pass
    
    
    def main():
        balance = eval(input(&#39;Enter the initial balance: &#39;))
        annual_interest_rate = eval(
            input(&#39;Enter the annual interest rate as a decimal: &#39;))
        lowest_payment = compute_fixed_monthly_payment(balance,
                                                       annual_interest_rate)
        print(&#39;Lowest Payment: &#39; + str(lowest_payment))
    
    
    if __name__ == &#39;__main__&#39;:
        main()

I am getting the following error:

    ModuleNotFoundError: No module named &#39;__main__.p_02_paying_debt_off_in_a_year&#39;; &#39;__main__&#39; is not a package

I have no idea how to solve this issue. I have tried adding a `__init__.py` file, but it is still not working.

  [1]: https://i.stack.imgur.com/naRKa.png



ModuleNotFoundError: What does it mean __main__ is not a package?

I would like to know how to format this case in a Pythonic way with f-strings:

    names = [&#39;Adam&#39;, &#39;Bob&#39;, &#39;Cyril&#39;]
    text = f&quot;Winners are:\n{&#39;\n&#39;.join(names)}&quot;
    print(text)

The problem is that `&#39;\&#39;` cannot be used inside the `{...}` expression portions of an f-string.
Expected output:

    Winners are:
    Adam
    Bob
    Cyril

How to use newline &#39;\n&#39; in f-string to format output in Python 3.6?

I just installed Python 3.6.1 for MacOS X

When I attempt to run the Console(or run anything with Python3), this error is thrown:

      AttributeError: module &#39;enum&#39; has no attribute &#39;IntFlag&#39;

    $ /Library/Frameworks/Python.framework/Versions/3.6/bin/python3  
    Failed to import the site module  
    Traceback (most recent call last):  
      File &quot;/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py&quot;, line 544, in &lt;module&gt;  
        main()  
      File &quot;/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py&quot;, line 530, in main  
        known_paths = addusersitepackages(known_paths)  
      File &quot;/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py&quot;, line 282, in addusersitepackages  
        user_site = getusersitepackages()  
      File &quot;/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py&quot;, line 258, in getusersitepackages  
        user_base = getuserbase() # this will also set USER_BASE  
      File &quot;/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site.py&quot;, line 248, in getuserbase  
        USER_BASE = get_config_var(&#39;userbase&#39;)  
      File &quot;/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/sysconfig.py&quot;, line 601, in get_config_var  
        return get_config_vars().get(name)  
      File &quot;/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/sysconfig.py&quot;, line 580, in get_config_vars  
        import _osx_support  
      File &quot;/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/_osx_support.py&quot;, line 4, in &lt;module&gt;  
        import re  
      File &quot;/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/re.py&quot;, line 142, in &lt;module&gt;  
        class RegexFlag(enum.IntFlag):  
    AttributeError: module &#39;enum&#39; has no attribute &#39;IntFlag&#39;  

The class IntFlag exists within enum.py. So, why is the AttributeError being thrown?

Why Python 3.6.1 throws AttributeError: module &#39;enum&#39; has no attribute &#39;IntFlag&#39;?

I&#39;m trying to write PEP-8 compliant code for a domestic project and I have a line with an f-string that is more than 80 characters long

![](https://i.stack.imgur.com/Wn6Jh.png) - the solid thin line near the dot at self.text is the 80 char mark.

I&#39;m trying to split it into different lines in the most *pythonic* way but the only aswer that actually works is an error for my linter

*Working Code:*

    def __str__(self):
        return f&#39;{self.date} - {self.time},\nTags:&#39; + \
        f&#39; {self.tags},\nText: {self.text}&#39;


*Output:*

    2017-08-30 - 17:58:08.307055,
    Tags: test tag,
    Text: test text

The linter thinks that i&#39;m not respecting E122 from PEP-8, is there a way to get the string right and the code compliant?

Multiline f-string in Python

I&#39;m trying to convert a fairly simple Python program to an executable and couldn&#39;t find what I was looking for, so I have a few questions (I&#39;m running Python&amp;nbsp;3.6):

The methods of doing this that I have found so far are as follows

 1. downloading an old version of Python and using `pyinstaller/py2exe`
 2. setting up a virtual environment in Python&amp;nbsp;3.6 that will allow me to do 1.
 3. downloading a Python to C++ converter and using that.

Here is what I&#39;ve tried/what problems I&#39;ve run into.

 - I installed `pyinstaller` before the required download before it (pypi-something) so it did not work. After downloading the prerequisite file, `pyinstaller` still does not recognize it.
 - If I&#39;m setting up a virtualenv in Python&amp;nbsp;2.7, do I actually need to have Python&amp;nbsp;2.7 installed?
 - similarly, the only python to C++ converters I see work only up until Python&amp;nbsp;3.5 - do I need to download and use this version if attempting this?




How can I convert a .py to .exe for Python?

Dictionaries are insertion ordered as of Python 3.6. It is described as a CPython implementation detail rather than a language feature. The [documentation][1] states:

&gt; `dict()` now uses a “compact” representation [pioneered by PyPy][2]. The memory usage of the new dict() is between 20% and 25% smaller compared to Python 3.5. [PEP 468][3] (Preserving the order of **kwargs in a function.) is implemented by this. The order-preserving aspect of this new implementation is considered an implementation detail and should not be relied upon (this may change in the future, but it is desired to have this new dict implementation in the language for a few releases before changing the language spec to mandate order-preserving semantics for all current and future Python implementations; this also helps preserve backwards-compatibility with older versions of the language where random iteration order is still in effect, e.g. Python 3.5). (Contributed by INADA Naoki in [issue 27350][4]. Idea [originally suggested by Raymond Hettinger][5].)


How does the new dictionary implementation perform better than the older one while preserving element order? 

---

Update December 2017: `dict`s retaining insertion order is [guaranteed][6] for Python 3.7


  [1]: https://docs.python.org/3.6/whatsnew/3.6.html#new-dict-implementation
  [2]: https://morepypy.blogspot.com/2015/01/faster-more-memory-efficient-and-more.html
  [3]: https://www.python.org/dev/peps/pep-0468
  [4]: https://bugs.python.org/issue27350
  [5]: https://mail.python.org/pipermail/python-dev/2012-December/123028.html
  [6]: https://mail.python.org/pipermail/python-dev/2017-December/151283.html

Are dictionaries ordered in Python 3.6+?

I am using template strings to generate some files and I love the conciseness of the new f-strings for this purpose, for reducing my previous template code from something like this:
     
    template_a = &quot;The current name is {name}&quot;
    names = [&quot;foo&quot;, &quot;bar&quot;]
    for name in names:
        print (template_a.format(**locals()))

Now I can do this, directly replacing variables:

    names = [&quot;foo&quot;, &quot;bar&quot;]
    for name in names:
        print (f&quot;The current name is {name}&quot;)

However, sometimes it makes sense to have the template defined elsewhere — higher up in the code, or imported from a file or something. This means the template is a static string with formatting tags in it. Something would have to happen to the string to tell the interpreter to interpret the string as a new f-string, but I don&#39;t know if there is such a thing.

**Is there any way to bring in a string and have it interpreted as an f-string to avoid using the `.format(**locals())` call?**

Ideally I want to be able to code like this... (where `magic_fstring_function` is where the part I don&#39;t understand comes in):

    template_a = f&quot;The current name is {name}&quot;
    # OR [Ideal2] template_a = magic_fstring_function(open(&#39;template.txt&#39;).read())
    names = [&quot;foo&quot;, &quot;bar&quot;]
    for name in names:
        print (template_a)

...with this desired output (without reading the file twice):

&lt;!-- language: lang-none --&gt;

    The current name is foo
    The current name is bar

...but the actual output I get is:

&lt;!-- language: lang-none --&gt;

    The current name is {name}
    The current name is {name}

How to postpone/defer the evaluation of f-strings?

I&#39;ve recently upgraded from `Ubuntu 18.04` to `19.04` which has `python 3.7`. But I work on many projects using `Python 3.6`. 

Now when I try to create a `virtualenv` with `Python 36` in PyCharm, it raises:

    ModuleNotFoundError: No module named &#39;distutils.core&#39;
[![enter image description here][1]][1]

I can&#39;t figure out what to do. 

I tried to install distutils:

    milano@milano-PC:~$ sudo apt-get install python3-distutils
    Reading package lists... Done
    Building dependency tree       
    Reading state information... Done
    python3-distutils is already the newest version (3.7.3-1ubuntu1).
    0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

But as you can see I have the newest version.

Do you know what to do?

  [1]: https://i.stack.imgur.com/kKMZC.png

ModuleNotFoundError: No module named &#39;distutils.core&#39;

Using %-formatting, I can specify the number of decimal cases in a string:

    x = 3.14159265
    print(&#39;pi = %0.2f&#39; %x)

This would give me:

    pi = 3.14

Is there any way of doing this using f-strings in Python 3.6?

Rounding floats with f-string

I just ran the following command:

    pip install -U steem

and the installation worked well until it failed to install `pycrypto`. 
Afterwards I did the

    pip install cryptography

command because I thought it was the missing package. 
So my question is, how I can install `steem` without the pycrypto-error (or the pycrypto-package in addition) and how to uninstall the cryptography-Package which I don&#39;t need. 
(I&#39;m using Windows 7 and Python 3)

    Requirement already up-to-date: python-dateutil in c:\users\***\appdata\lo
    cal\programs\python\python36\lib\site-packages (from dateparser-&gt;maya-&gt;steem)
    ...
    Installing collected packages: urllib3, idna, chardet, certifi, requests, pycryp
    to, funcy, w3lib, voluptuous, diff-match-patch, scrypt, prettytable, appdirs, la
    ngdetect, ruamel.yaml, humanize, tzlocal, regex, dateparser, pytzdata, pendulum,
    maya, ecdsa, pylibscrypt, ujson, toolz, steem
    Running setup.py install for pycrypto ... error
    Complete output from command c:\users\***\appdata\local\programs\pytho
    n\python36\python.exe -u -c &quot;import setuptools, tokenize;__file__=&#39;C:\\Users\\
    ***~1\\AppData\\Local\\Temp\\pip-build-k6flhu5k\\pycrypto\\setup.py&#39;;f=getattr(
    tokenize, &#39;open&#39;, open)(__file__);code=f.read().replace(&#39;\r\n&#39;, &#39;\n&#39;);f.close();
    exec(compile(code, __file__, &#39;exec&#39;))&quot; install --record C:\Users\***N~1\AppDat
    a\Local\Temp\pip-igpkll6u-record\install-record.txt --single-version-externally-
    managed --compile:
    running install
    running build
    running build_py
    ...
    building &#39;Crypto.Random.OSRNG.winrandom&#39; extension
    error: Microsoft Visual C++ 14.0 is required. Get it with &quot;Microsoft Visual
    C++ Build Tools&quot;: http://landinghub.visualstudio.com/visual-cpp-build-tools

    ----------------------------------------
    Command &quot;c:\users\***\appdata\local\programs\python\python36\python.exe -u
    -c &quot;import setuptools, tokenize;__file__=&#39;C:\\Users\\***N~1\\AppData\\Local\\
    Temp\\pip-build-k6flhu5k\\pycrypto\\setup.py&#39;;f=getattr(tokenize, &#39;open&#39;, open)(
    __file__);code=f.read().replace(&#39;\r\n&#39;, &#39;\n&#39;);f.close();exec(compile(code,   __fil
    e__, &#39;exec&#39;))&quot; install --record C:\Users\***N~1\AppData\Local\Temp\pip-igpkll6
    u-record\install-record.txt --single-version-externally-managed --compile&quot;   faile
    d with error code 1 in C:\Users\***N~1\AppData\Local\Temp\pip-build-    k6flhu5k\p
    ycrypto\

Pip error: Microsoft Visual C++ 14.0 is required

I am getting an error while running this part of the code. I tried some of the existing solutions, but none of them helped.

    elec_and_weather = pd.read_csv(r&#39;C:\HOUR.csv&#39;, parse_dates=True,index_col=0)
    # Add historic DEMAND to each X vector
     for i in range(0,24):
        elec_and_weather[i] = np.zeros(len(elec_and_weather[&#39;DEMAND&#39;]))
        elec_and_weather[i][elec_and_weather.index.hour==i] = 1
    # Set number of hours prediction is in advance
    n_hours_advance = 24

    # Set number of historic hours used
    n_hours_window = 24

    for k in range(n_hours_advance,n_hours_advance+n_hours_window):
        elec_and_weather[&#39;DEMAND_t-%i&#39;% k] = np.zeros(len(elec_and_weather[&#39;DEMAND&#39;]))&#39;


 
I always get this error:

    for i in range(0,24):
    File &quot;&lt;ipython-input-29-db3022a769d1&gt;&quot;, line 1
    for i in range(0,24):
                         ^
    SyntaxError: unexpected EOF while parsing

    File &quot;&lt;ipython-input-25-df0a44131c36&gt;&quot;, line 1
        for k in range(n_hours_advance,n_hours_advance+n_hours_window):
                                                                       ^
    SyntaxError: unexpected EOF while parsing



SyntaxError: unexpected EOF while parsing

I tried to read https://hackernoon.com/asynchronous-python-45df84b82434.
It&#39;s about asynchronous python and I tried the code from this, but I&#39;m getting a weird Error.
The code is:
`

    import asyncio
    import aiohttp
    
    urls = [&#39;http://www.google.com&#39;, &#39;http://www.yandex.ru&#39;, &#39;http://www.python.org&#39;]
    
    async def call_url(url):
        print(&#39;Starting {}&#39;.format(url))
        response = await aiohttp.ClientSession().get(url)
        data = await response.text()
        print(&#39;{}: {} bytes: {}&#39;.format(url, len(data), data))
        return data
    
    futures = [call_url(url) for url in urls]
    
    asyncio.run(asyncio.wait(futures))


When I try to run it says:

    
    Traceback (most recent call last):
      File &quot;test.py&quot;, line 15, in &lt;module&gt;
        asyncio.run(asyncio.wait(futures))
    AttributeError: module &#39;asyncio&#39; has no attribute &#39;run&#39;
    sys:1: RuntimeWarning: coroutine &#39;call_url&#39; was never awaited
    
    

I dont have any files named ayncio and I have proof:

    &gt;&gt;&gt; asyncio
    &lt;module &#39;asyncio&#39; from &#39;/usr/lib/python3.6/asyncio/__init__.py&#39;&gt;


Python3.6 AttributeError: module &#39;asyncio&#39; has no attribute &#39;run&#39;

I&#39;m trying to compile Python 3.6 on an arm based Linux machine, 
`./configure` outputs this:

&gt; If you want a release build with all optimizations active (LTO, PGO, etc),
please run `./configure --enable-optimizations`.

what does `--enable-optimizations` do?


what does --enable-optimizations do while compiling python?

I get what the new f strings in python 3.6 do, but what about the ending !r as found in the code snip below. 

    def __repr__(self):
        return (f&#39;Pizza({self.radius!r}, &#39;f&#39;{self.ingredients!r})&#39;)

In Python format (f-string) strings, what does !r mean?

I am learning to use &#39;pillow 5.0&#39; following book &#39;Automate the boring stuff with python&#39;

The info about the image object

    In [79]: audacious = auda
    In [80]: print(audacious.format, audacious.size, audacious.mode)
    PNG (1094, 960) RGBA

When I tried to convert filetype, it report error.

    In [83]: audacious.save(&#39;audacious.jpg&#39;)
    OSError: cannot write mode RGBA as JPEG
There&#39;s no such a
n error in book.

cannot write mode RGBA as JPEG

I&#39;m trying to install tensorflow onto a Mac with Python3.7. However, I&#39;m getting the error:

    $ pip3 -v install tensorflow
    ...    
        Skipping link https://files.pythonhosted.org/packages/56/7a/c6bca0fe52a94ca508731d8b139e7dbd5a36cddc64c19f422f97e5a853e8/tensorflow-1.10.0rc1-cp36-cp36m-win_amd64.whl#sha256=3ab24374888d6a13d55ce2e3cf4ba0c9cd6f824723313db5322512087525cb78 (from https://pypi.org/simple/tensorflow/); it is not compatible with this Python
      Could not find a version that satisfies the requirement tensorflow (from versions: )
    Cleaning up...
    Removed build tracker &#39;/private/var/folders/4n/9342s4wd3jv0qzwjz8rxrygr0000gp/T/pip-req-tracker-3p60r2lo&#39;

    No matching distribution found for tensorflow

From what I can gather this is happening because tensorflow doesn&#39;t yet support Python3.7. As a workaround I want to install Python3.6 alongside 3.7 and then install tensorflow to that version. However, I&#39;m new to Mac and not sure of the correct way to do this without potentially messing with the preexisting Python version. 

I&#39;ve tried using brew, but it looks like Python3 is as specific as it gets. What is the correct way to do what I&#39;m after?

Installing Python3.6 alongside Python3.7 on Mac

Thanks to [David Beazley&#39;s tweet][1], I&#39;ve recently found out that the new [Python 3.6 f-strings][2] can also be nested:

    &gt;&gt;&gt; price = 478.23
    &gt;&gt;&gt; f&quot;{f&#39;${price:0.2f}&#39;:*&gt;20s}&quot;
    &#39;*************$478.23&#39;

Or:

    &gt;&gt;&gt; x = 42
    &gt;&gt;&gt; f&#39;&#39;&#39;-{f&quot;&quot;&quot;*{f&quot;+{f&#39;.{x}.&#39;}+&quot;}*&quot;&quot;&quot;}-&#39;&#39;&#39;
    &#39;-*+.42.+*-&#39;

While I am surprised that this is possible, I am missing on how practical is that, when would nesting f-strings be useful? What use cases can this cover?

Note: The PEP itself does not mention nesting f-strings, but there is a [specific test case][3].


  [1]: https://twitter.com/dabeaz/status/810217326293479425?lang=en
  [2]: https://www.python.org/dev/peps/pep-0536/
  [3]: https://github.com/python/cpython/blob/master/Lib/test/test_fstring.py#L536

Nested f-strings

I&#39;m trying out Python 3.6. Going through new code, I stumbled upon this new syntax:

    f&quot;My formatting string!&quot;

It seems we can do things like this:

    &gt;&gt;&gt; name = &quot;George&quot;
    &gt;&gt;&gt; print(f&quot;My cool string is called {name}.&quot;)
    My cool string is called George.

Can anyone shed some light on the inner workings of this? In particular what is the scope of the variables that an f-prefixed string can take?

    

String with &#39;f&#39; prefix in python-3.6


 - What does the **`m`** stand for in `python3.6m` ? 
 - How does it differ to non **`m`** version?
 - In which case would I prefer to use `python3.6m` rather than `python3.6`?


All Python 3.6 Solutions on Gang of Coders

Total of 24 Python 3.6 Solutions