Try this if you are on ubuntu:

    sudo apt-get update
    sudo apt-get install build-essential libpq-dev libssl-dev openssl libffi-dev zlib1g-dev
    sudo apt-get install python3-pip python3.7-dev
    sudo apt-get install python3.7

In case you don&#39;t have the repository and so it fires a not-found package you first have to install this:

    sudo apt-get install -y software-properties-common
    sudo add-apt-repository ppa:deadsnakes/ppa
    sudo apt-get update

more info here: http://devopspy.com/python/install-python-3-6-ubuntu-lts/

On ubuntu you can add this PPA Repository and use it to install python 3.7: 
https://launchpad.net/~jonathonf/+archive/ubuntu/python-3.7

Or a different PPA that provides several Python versions is Deadsnakes:
https://launchpad.net/~deadsnakes/+archive/ubuntu/ppa

See also here: https://askubuntu.com/questions/865554/how-do-i-install-python-3-6-using-apt-get (I know it says 3.6 in the url, but the deadsnakes ppa also contains 3.7 so you can use it for 3.7 just the same) 
  
  
  
  
  
  
If you want &quot;official&quot; you&#39;d have to install it from the sources from the site, get the code (which you already downloaded) and do this: 

    tar -xf Python-3.7.0.tar.xz
    cd Python-3.7.0
    ./configure
    make
    sudo make install        &lt;-- sudo is required.
This might take a while


I have 5 widgets with different sizes which would overflow if placed next to each other.

I am looking for a layout helper class that limits the widgets to the horizontal space and auto-wraps the widgets instead to a new line. First I was looking for a grid view but prefer instead a view which is independent since all elements have different widths. A multi line text field does actually already that, I just need the same approach with my widgets. Any ideas?

    &lt;Widget&gt;[
        new RaisedButton(child: const Text(&#39;Foo&#39;)),
        new RaisedButton(child: const Text(&#39;Foo Bar&#39;)),
        new RaisedButton(child: const Text(&#39;Foo Bar Bas&#39;)),
        new RaisedButton(child: const Text(&#39;F&#39;)),
        new RaisedButton(child: const Text(&#39;B&#39;))
    ]


Autowrap widgets to new line in flutter

The code at [this GitHub file][1] uses a C++ variable &quot;declaration&quot; syntax I&#39;m not familiar with:

	std::unique_ptr&lt;CRecentFileList&gt; {m_pRecentFileList} = std::make_unique&lt;CRecentFileList&gt;(...

(`m_pRecentFileList` is declarared in a superclass.)

What does it mean when you wrap a variable **declaration** in braces? (not an initializer list)

----------

I extracted a minimal test case which compiles:

    class foo {
        int* p;
        void f(){
            std::unique_ptr&lt;int&gt; {p} = std::make_unique&lt;int&gt;(1);
        }
    };

Changing `int* p` to `std::unique_ptr&lt;int&gt; p` creates a compilation error due to `unique_ptr(const unique_ptr&amp;) = delete;`

This makes me think braced declaration assigns to a outer-scope variable with the same name. I tried creating a test program, but it fails to compile:

    int main(){
        int x;
        int {x} = 1;
    }

&gt; `error: using temporary as lvalue [-fpermissive]`


  [1]: https://github.com/HertzDevil/0CC-FamiTracker/blob/e643e8cbad1c8bf01ff706245d72f93c33417de8/Source/FamiTracker.cpp#L446

In C++, what do braces on the left-hand side of a variable declaration mean?

I have python3.5 already in linux ubuntu. I have downloaded the python3.7.tar [www.python.org][1].

But i have no idea how to install it. How to upgrade to python 3.7? Thanks.



  [1]: http://www.python.org

How to upgrade Python version to 3.7?

<p>I have python3.5 already in linux ubuntu. I have downloaded the python3.7.tar <a href="http://www.python.org" target="_blank" rel="noopener noreferrer">www.python.org</a>.</p>
<p>But i have no idea how to install it. How to upgrade to python 3.7? Thanks.</p>


Starting with Python 3.7, there is something called a dataclass:


    from dataclasses import dataclass
    
    @dataclass
    class Foo:
        x: str


However, the following fails:

    &gt;&gt;&gt; import json
    &gt;&gt;&gt; foo = Foo(x=&quot;bar&quot;)
    &gt;&gt;&gt; json.dumps(foo)
    TypeError: Object of type Foo is not JSON serializable


How can I make `json.dumps()` encode instances of `Foo` into json [*objects*](https://www.json.org/)?

Make the Python json encoder support Python&#39;s new dataclasses

Here is this issue:
I attempt to install mysqlclient like so

    C:\Users\amccommon349&gt;pip install mysqlclient
    Collecting mysqlclient
      Using cached https://files.pythonhosted.org/packages/ec/fd/83329b9d3e14f7344d1
    cb31f128e6dbba70c5975c9e57896815dbb1988ad/mysqlclient-1.3.13.tar.gz
    Installing collected packages: mysqlclient
      Running setup.py install for mysqlclient ... error
        Complete output from command c:\users\amccommon349\appdata\local\programs\python\python36\python.exe -u -c &quot;import setuptools, tokenize;__file__=&#39;C:\\Users\\AMCCOM~1\\AppData\\Local\\Temp\\pip-install-qcgo48hf\\mysqlclient\\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\AMCCOM~1\AppData\Local\Temp\pip-record-q4yoftj8\install-record.txt --single-version-externally-managed --compile:

    c:\users\amccommon349\appdata\local\programs\python\python36\lib\distutils\dist.py:261: UserWarning: Unknown distribution option: &#39;long_description_content_type&#39;
    warnings.warn(msg)
    running install
    running build
    running build_py
    creating build
    creating build\lib.win-amd64-3.6
    copying _mysql_exceptions.py -&gt; build\lib.win-amd64-3.6
    creating build\lib.win-amd64-3.6\MySQLdb
    copying MySQLdb\__init__.py -&gt; build\lib.win-amd64-3.6\MySQLdb
    copying MySQLdb\compat.py -&gt; build\lib.win-amd64-3.6\MySQLdb
    copying MySQLdb\connections.py -&gt; build\lib.win-amd64-3.6\MySQLdb
    copying MySQLdb\converters.py -&gt; build\lib.win-amd64-3.6\MySQLdb
    copying MySQLdb\cursors.py -&gt; build\lib.win-amd64-3.6\MySQLdb
    copying MySQLdb\release.py -&gt; build\lib.win-amd64-3.6\MySQLdb
    copying MySQLdb\times.py -&gt; build\lib.win-amd64-3.6\MySQLdb
    creating build\lib.win-amd64-3.6\MySQLdb\constants
    copying MySQLdb\constants\__init__.py -&gt; build\lib.win-amd64-3.6\MySQLdb\constants
    copying MySQLdb\constants\CLIENT.py -&gt; build\lib.win-amd64-3.6\MySQLdb\constants
    copying MySQLdb\constants\CR.py -&gt; build\lib.win-amd64-3.6\MySQLdb\constants
    copying MySQLdb\constants\ER.py -&gt; build\lib.win-amd64-3.6\MySQLdb\constants
    copying MySQLdb\constants\FIELD_TYPE.py -&gt; build\lib.win-amd64-3.6\MySQLdb\constants
    copying MySQLdb\constants\FLAG.py -&gt; build\lib.win-amd64-3.6\MySQLdb\constants
    copying MySQLdb\constants\REFRESH.py -&gt; build\lib.win-amd64-3.6\MySQLdb\constants
    running build_ext
    building &#39;_mysql&#39; extension
    creating build\temp.win-amd64-3.6
    creating build\temp.win-amd64-3.6\Release
    C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\VC\Tools\MSVC\14.14.26428\bin\HostX86\x64\cl.exe /c/nologo/Ox /W3 /GL /DNDEBUG /MD -Dversion_info=(1,3,13,&#39;final&#39;,0) -D__version__=1.3.13 &quot;-IC:\Program Files (x86)\MySQL\MySQL Connector C 6.1\include&quot; -Ic:\users\amccommon349\appdata\local\programs\python\python36\include -Ic:\users\amccommon349\appdata\local\programs\python\python36\include &quot;-IC:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\VC\Tools\MSVC\14.14.26428\include&quot; &quot;-IC:\Program Files (x86)\Windows Kits\NETFXSDK\4.6.1\include\um&quot; &quot;-IC:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\ucrt&quot; &quot;-IC:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\shared&quot; &quot;-IC:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um&quot; &quot;-IC:\ProgramFiles (x86)\Windows Kits\10\include\10.0.17134.0\winrt&quot; &quot;-IC:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\cppwinrt&quot; /Tc_mysql.c /Fobuild\temp.win-amd64-3.6\Release\_mysql.obj /Zl _mysql.c
    _mysql.c(29): fatal error C1083: Cannot open include file: &#39;mysql.h&#39;: No such file or directory
      error: command &#39;C:\\Program Files (x86)\\Microsoft Visual Studio\\2017\\BuildTools\\VC\\Tools\\MSVC\\14.14.26428\\bin\\HostX86\\x64\\cl.exe&#39; failed with exit status 2

I made sure I had all of the files needed from visual studios build tools, I downloaded the mysql-python connector, and updated my pip and setup tools. I am a complete beginner to this and would appreciate any input as to how to go about fixing this error.


pip install mysqlclient returns &quot;fatal error C1083: Cannot open file: &#39;mysql.h&#39;: No such file or directory

How do I use **TensorFlow GPU** version instead of **CPU** version in Python 3.6 x64?

    import tensorflow as tf

Python is using my **CPU** for calculations. &lt;br/&gt;
I can notice it because I have an error:

&gt; Your CPU supports instructions that this TensorFlow binary was not
&gt; compiled to use: AVX2

I have installed tensorflow and tensorflow-gpu.



How do I switch to GPU version? 


  

How do I use TensorFlow GPU?

Can anyone explain the concepts of these two ideas and how they relate to making relationships between tables? I can&#39;t really seem to find anything that explains it clearly and the documentation feels like there&#39;s too much jargon to understand in easy concepts. For instance, in this example of a one to many relationship in the documentation:

    class Parent(Base):
        __tablename__ = &#39;parent&#39;
        id = Column(Integer, primary_key=True)
        children = relationship(&quot;Child&quot;, back_populates=&quot;parent&quot;)
    
    class Child(Base):
        __tablename__ = &#39;child&#39;
        id = Column(Integer, primary_key=True)
        parent_id = Column(Integer, ForeignKey(&#39;parent.id&#39;))
        parent = relationship(&quot;Parent&quot;, back_populates=&quot;children&quot;)

Why does the `relationship()` go inside the parent class while `ForeignKey` goes inside the child class? And what does having `back_populates` exactly do to one another? Does having the placement of which class the `relationship()` function exist in matter?

 


Concepts of backref and back_populate in SQLalchemy?

In a project, I have e.g. two different packages, How can I use the setup.py to install these two packages in the Google&#39;s Colab, so that I can import the packages?

How do I install Python packages in Google&#39;s Colab?

### Background

In the last year I was using the nlohmann json library&lt;sup&gt;[1]&lt;/sup&gt; and was cross-compiling on x86_64 using GCC 5.x `arm-linux-gnueabi-*` with no warnings. When I updated GCC to a newer version, GCC would generate pages of cryptic diagnostic notes. For example, here is one of the notes

    In file included from /usr/arm-linux-gnueabi/include/c++/7/vector:69:0,
                 from include/json.hpp:58,
                 from src/write_hsi.cpp:23:
    /usr/arm-linux-gnueabi/include/c++/7/bits/vector.tcc: In member function ‘void std::vector&lt;_Tp, _Alloc&gt;::_M_realloc_insert(std::vector&lt;_Tp, _Alloc&gt;::iterator, _Args&amp;&amp; ...) [with _Args = {nlohmann::basic_json&lt;std::map, std::vector, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt;, bool, long long int, long long unsigned int, double, std::allocator, nlohmann::adl_serializer&gt;}; _Tp = nlohmann::basic_json&lt;&gt;; _Alloc = std::allocator&lt;nlohmann::basic_json&lt;&gt; &gt;]’:
    /usr/arm-linux-gnueabi/include/c++/7/bits/vector.tcc:394:7: note: parameter passing for argument of type ‘std::vector&lt;nlohmann::basic_json&lt;&gt;, std::allocator&lt;nlohmann::basic_json&lt;&gt; &gt; &gt;::iterator {aka __gnu_cxx::__normal_iterator&lt;nlohmann::basic_json&lt;&gt;*, std::vector&lt;nlohmann::basic_json&lt;&gt;, std::allocator&lt;nlohmann::basic_json&lt;&gt; &gt; &gt; &gt;}’ changed in GCC 7.1
       vector&lt;_Tp, _Alloc&gt;::
       ^~~~~~~~~~~~~~~~~~~
    /usr/arm-linux-gnueabi/include/c++/7/bits/vector.tcc: In member function ‘nlohmann::basic_json&lt;ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer&gt; nlohmann::basic_json&lt;ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer&gt;::parser::parse_internal(bool) [with ObjectType = std::map; ArrayType = std::vector; StringType = std::__cxx11::basic_string&lt;char&gt;; BooleanType = bool; NumberIntegerType = long long int; NumberUnsignedType = long long unsigned int; NumberFloatType = double; AllocatorType = std::allocator; JSONSerializer = nlohmann::adl_serializer]’:
    /usr/arm-linux-gnueabi/include/c++/7/bits/vector.tcc:105:21: note: parameter passing for argument of type ‘__gnu_cxx::__normal_iterator&lt;nlohmann::basic_json&lt;&gt;*, std::vector&lt;nlohmann::basic_json&lt;&gt;, std::allocator&lt;nlohmann::basic_json&lt;&gt; &gt; &gt; &gt;’ changed in GCC 7.1
    _M_realloc_insert(end(), std::forward&lt;_Args&gt;(__args)...);
    ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It was easy to find a solution, namely by adding `-Wno-psabi` to the compiler options. In fact, that was the fix implemented in the library.&lt;sup&gt;[2]&lt;/sup&gt;

I understand the basics of Application Binary Interfaces (ABIs) and processor-specific ABIs (psABIs). For reference, this answer&lt;sup&gt;[11]&lt;/sup&gt; gives a quick overview of ABIs:

&gt; An ABI (_**Application Binary Interface**_) is a standard that defines a mapping between low-level concepts in high-level languages and the abilities of a specific hardware/OS platform&#39;s machine code. That includes things like:
&gt; 
&gt;  - how C/C++/Fortran/... **data types** are laid out in memory (data sizes / alignments)
&gt;  - how nested **function calls** work (where and how the information on how to return to a function&#39;s caller is stored, where in the CPU registers and/or in memory function arguments are passed)
&gt;  - how **program startup / initialization** works (what data format an &quot;executable&quot; has, how the code / data is loaded from there, how DLLs work ...)
&gt; 
&gt; The answers to these are:
&gt; 
&gt;  - _language-specific_ (hence you&#39;ve got a C ABI, C++ ABI, Fortran ABI, Pascal ABI, ... even the Java bytecode spec, although targeting a &quot;virtual&quot; processor instead of real hardware, is an ABI),
&gt;  - _operating-system specific_ (MS Windows and Linux on the same hardware use a different ABI),
&gt;  - _hardware/CPU-specific_ (the ARM and x86 ABIs are different).
&gt;  - _evolving over (long) time_ (existing ABIs have often been updated / rev&#39;ed so that new CPU features could be made use of, like, say, specifying how the x86 SSE registers are to be used by apps was of course only possible once CPUs _had_ these regs, therefore existing ABIs needed to be clarified).

So the ABI is the overarching component, and one of its components (the &quot;hardware/CPU-specific&quot; details) is the psABI.

### My Issue

The problem I am having is

 1. I don&#39;t like universally disabling warnings without understanding the implications.
 2. The advice &quot;use `-Wno-psabi` to make the notes go away&quot; seems to be pretty common advice for these types of diagnostic notes that &quot;suddenly appear&quot; after a compiler upgrade.&lt;sup&gt;[2]&lt;/sup&gt;&lt;sup&gt;[3]&lt;/sup&gt;&lt;sup&gt;[4]&lt;/sup&gt; Even the one of the GCC developers suggest doing this.&lt;sup&gt;[5]&lt;/sup&gt;
 3. Neither `-Wpsabi` nor `-Wno-psabi` are documented&lt;sup&gt;[6]&lt;/sup&gt; in the GCC manual.&lt;sup&gt;[7]&lt;/sup&gt;

As a result I am not really sure what exactly `-Wno-psabi` will and will not affect. A related option `-Wabi` *is* documented:&lt;sup&gt;[8]&lt;/sup&gt;

&gt; `-Wabi (C, Objective-C, C++ and Objective-C++ only)`
&gt;
&gt;    Warn when G++ it generates code that is probably not compatible with the vendor-neutral C++ ABI...
&gt;
&gt; It also warns about psABI-related changes. The known psABI changes at this point include: 
&gt;
&gt; - For SysV/x86-64, unions with long double members are passed in memory as specified in psABI. For example: 
&gt;
&gt; `    union U {`
&gt; `     long double ld;`
&gt; `     int i;`
&gt; `    };`
&gt;
&gt; `union U` is always passed in memory.

My understanding of this all is

1. `-Wabi` will generate warnings when there is a psABI change.
2. GCC 7 fixed an ABI bug&lt;sup&gt;[9]&lt;/sup&gt; introduced in GCC 5 that affects ARM targets.
    - In the release notes it is stated &quot;this is an ABI change.&quot;&lt;sup&gt;[10]&lt;/sup&gt;
    - For some reason the release notes state that the related diagnostic notes are generated when using the undocumented `-Wpsabi`, not the documented `-Wabi`.
    - This ABI change is not mentioned in the manual.
3. Putting together &quot;this is an ABI change&quot; and &quot;use `-Wpsabi`&quot;, it appears to me this is *specifically* a psABI change, not a different kind of ABI change. (In reality it is a change in GCC&#39;s implementation of the psABI, not the psABI itself)

I know that documentation isn&#39;t always up to date, especially for something that is a known undocumented option. But my concern is that &quot;use `-Wno-psabi`&quot; seems to be the standard response for several different kinds of these cryptic diagnostic notes. But, in my basic understanding of ABIs, isn&#39;t an ABI change a big deal? Shouldn&#39;t I be concerned about an ABI change, rather than just making the message go away? Between the undocumented stuff and some of the finer details of ABI vs psABI, I&#39;m not really sure...

For example, if I add `-Wno-psabi` to my makefile to make those notes go away, what if there is another ABI change in the future that *does* affect my project? Have I effectively silenced future warnings or notes that may be important?

Also, even though we are told &quot;if you recompile all the code, there is nothing to worry about,&quot;&lt;sup&gt;[5]&lt;/sup&gt; what exactly is &quot;all the code&quot;? Is that my source code? glibc? Any other system-wide shared library I might be using?

### References

1. https://github.com/nlohmann/json
2. https://github.com/nlohmann/json/issues/658
3. https://stackoverflow.com/a/48149400
4. https://stackoverflow.com/a/13915796/10270632
5. https://gcc.gnu.org/ml/gcc/2017-05/msg00073.html
6. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81831
7. https://gcc.gnu.org/onlinedocs/gcc-8.2.0/gcc
8. https://gcc.gnu.org/onlinedocs/gcc-8.2.0/gcc/C_002b_002b-Dialect-Options.html
9. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77728
10. https://gcc.gnu.org/gcc-7/changes.html
11. https://stackoverflow.com/a/8063350

What exactly does GCC&#39;s -Wpsabi option do? What are the implications of supressing it?

I&#39;m running Debian on Windows 10 (Windows Subsystem for Linux) and installed Rust using the command:

&lt;!-- language: bash --&gt;

    curl https://sh.rustup.rs -sSf | sh

There were no errors in the install, but when I tried to compile with `rustc` I got the error `linker &#39;cc&#39; not found`.

How do I fix the Rust error &quot;linker &#39;cc&#39; not found&quot; for Debian on Windows 10?

I have a C program that compiles to an executable called myprogram. This is its main function:

    int main(int argc, char ** argv) {
	  printf(&quot;this is a test message.\n&quot;);
	  system(&quot;ls&quot;);
    
      return 0;
    }

When I run `myprogram &gt; output.txt` in a Linux shell and then examine output.txt, I see the output of `ls` listed above &quot;this is a test message.&quot; 

I feel like it should be the other way around. Why is this happening, and what can I do so that &quot;this is a test message&quot; appears at the top of output.txt?  

If it matters, I&#39;m new to both C and working in a command line.

Results of printf() and system() are in the wrong order when output is redirected to a file

I have a program, in which I need to convert a PDF to an image using Image Magick. I do that using the `subprocess` package:

            cmd = &#39;magick convert -density 300 &#39;+pdfFile+&#39;[&#39;+str(rangeTuple[0])+&#39;-&#39;+str(rangeTuple[1])+&#39;] -depth 8 &#39;+&#39;temp.tiff&#39; #WINDOWS
            if(os.path.isfile(&#39;temp.tiff&#39;)):
                os.remove(&#39;temp.tiff&#39;)
            subprocess.call(cmd,shell=True)
            im = Image.open(&#39;temp.tiff&#39;)
The error I got is:

    convert-im6.q16: not authorized `temp2.pdf&#39; @ error/constitute.c/ReadImage/412.
    convert-im6.q16: no images defined `temp.tiff&#39; @ error/convert.c/ConvertImageCommand/3258.
    Traceback (most recent call last):
      File &quot;UKExtraction2.py&quot;, line 855, in &lt;module&gt;
        doItAllUpper(&quot;A0&quot;,&quot;UK5.csv&quot;,&quot;temp&quot;,59,70,&quot;box&quot;,2,1000,firstPageCoordsUK,boxCoordUK,voterBoxCoordUK,internalBoxNumberCoordUK,externalBoxNumberCoordUK,addListInfoUK)
      File &quot;UKExtraction2.py&quot;, line 776, in doItAllUpper
        doItAll(tempPDFName,outputCSV,2,pdfs,formatType,n_blocks,writeBlockSize,firstPageCoords,boxCoord,voterBoxCoord,internalBoxNumberCoord,externalBoxNumberCoord,addListInfo,pdfName)
      File &quot;UKExtraction2.py&quot;, line 617, in doItAll
        mainProcess(pdfName,(0,noOfPages-1),formatType,n_blocks,outputCSV,writeBlockSize,firstPageCoords,boxCoord,voterBoxCoord,internalBoxNumberCoord,externalBoxNumberCoord,addListInfo,bigPDFName,basePages)
      File &quot;UKExtraction2.py&quot;, line 542, in mainProcess
        im = Image.open(&#39;temp.tiff&#39;)
      File &quot;/home/rohit/.local/lib/python3.6/site-packages/PIL/Image.py&quot;, line 2609, in open
        fp = builtins.open(filename, &quot;rb&quot;)
    FileNotFoundError: [Errno 2] No such file or directory: &#39;temp.tiff&#39;

The most important of which is:

    convert-im6.q16: not authorized `temp2.pdf&#39; @ error/constitute.c/ReadImage/412.

I think this is because ImageMagick isn&#39;t authorized to access the PDF. What should be done now? I&#39;m on a Linux server. Any help is appreciated.



ImageMagick not authorized to convert PDF to an image

The Imagemagick security policy seems to be not allowing me perform this conversion from pdf to png. Converting other extensions seem to be working, just not from pdf. I haven&#39;t changed any of the imagemagick settings since I installed it... I am using Arch Linux, if the OS matters.

    user@machine $ convert -density 300 -depth 8 -quality 90 input.pdf output.png
    convert: attempt to perform an operation not allowed by the security policy `PDF&#39; @ error/constitute.c/IsCoderAuthorized/408.
    convert: no images defined `output.png&#39; @ error/convert.c/ConvertImageCommand/3288.

ImageMagick security policy &#39;PDF&#39; blocking conversion

I&#39;m using Python&#39;s Pathlib and I want to take something like

    p = Path(&#39;/path/to/foo&#39;)

And then try a couple of different extensions. I can do

    for ext in [&#39;.txt&#39;, &#39;.md&#39;, &#39;.note&#39;]
        filename = Path(str(p) + ext)

but that feels a little awkward. Is there a better way to do this?

Is there an idiomatic way to add an extension using Python&#39;s Pathlib?

I am trying to install dependencies using `pip3` command

current scenario:

    Dev$ which python
    /Users/Dev/anaconda/bin/python
    
    Dev$ which python3
    /usr/local/bin/python3


    Dev$ pip --version
    pip 10.0.1 from /usr/local/lib/python2.7/site-packages/pip (python 2.7)
    
    Dev$ pip3 --version
    -bash: /usr/local/bin/pip3: /usr/local/opt/python3/bin/python3.6: bad 
    interpreter: No such file or directory


I have no idea why my `pip3` command is not working. 

I have tried things like this:
    
    brew link --overwrite python 




pip3: bad interpreter: No such file or directory

I am using [`pipenv`](https://pipenv.kennethreitz.org/) to handle Python package dependencies.

The Python package is using two packages (named `pckg1` and `pckg2`) that rely on the same package named `pckg3`, **but from two different versions**. Showing the dependency tree :

    $ pipenv graph
      pckg1==3.0.0
        - pckg3 [required: &gt;=4.1.0]
      pckg2==1.0.2
        - pckg3 [required: ==4.0.11]

An attempt to install dependencies :

    $ pipenv install

    Warning: Your dependencies could not be resolved. You likely have a mismatch in your sub-dependencies.
    You can use $ pipenv install --skip-lock to bypass this mechanism, then run $ pipenv graph to inspect the situation.
    Hint: try $ pipenv lock --pre if it is a pre-release dependency.
    Could not find a version that matches pckg3==4.0.11,==4.1.0,&gt;=4.1.0 (from -r C:\Users\user\AppData\Local\Temp\pipenv-o7uxm080-requirements\pipenv-hwekv7dc-constraints.txt (line 2))
    Tried: 3.3.1, 3.3.2, 3.3.3, 3.4.0, 3.4.2, 4.0.0, 4.0.0, 4.0.1, 4.0.1, 4.0.2, 4.0.2, 4.0.3, 4.0.3, 4.0.4, 4.0.4, 4.0.6, 4.0.6, 4.0.8, 4.0.8, 4.0.9, 4.0.9, 4.0.10, 4.0.10, 4.0.11, 4.0.11, 4.1.0, 4.1.0, 4.1.1, 4.1.1, 4.1.2, 4.1.2, 4.2.1, 4.2.1, 4.3.0, 4.3.0
    There are incompatible versions in the resolved dependencies.

As suggested, `pip install --skip-lock` does the trick, but the dependency tree is still unresolved.

I would love to tell `Pipenv` to override `pckg2`&#39;s requirement, and specify `pckg3&gt;=4.1.0`.

How can this be resolved?

How to resolve Python package dependencies with pipenv?

I&#39;m currently trying my hands on the new dataclass constructions introduced in Python 3.7. I am currently stuck on trying to do some inheritance of a parent class. It looks like the order of the arguments are botched by my current approach such that the bool parameter in the child class is passed before the other parameters. This is causing a type error.

    from dataclasses import dataclass
    
    @dataclass
    class Parent:
        name: str
        age: int
        ugly: bool = False
    
        def print_name(self):
            print(self.name)
    
        def print_age(self):
            print(self.age)
    
        def print_id(self):
            print(f&#39;The Name is {self.name} and {self.name} is {self.age} year old&#39;)
    
    @dataclass
    class Child(Parent):
        school: str
        ugly: bool = True
    

    jack = Parent(&#39;jack snr&#39;, 32, ugly=True)
    jack_son = Child(&#39;jack jnr&#39;, 12, school = &#39;havard&#39;, ugly=True)
    
    jack.print_id()
    jack_son.print_id()


When I run this code I get this `TypeError`:

    TypeError: non-default argument &#39;school&#39; follows default argument

How do I fix this?

Class inheritance in Python 3.7 dataclasses

I recently installed Python 3.7 and at the end of the setup, there is the option to &quot;Disable path length limit&quot;. I don&#39;t know whether or not I should do this. 

What are the pros and cons of doing this? Just from the sound of it you should always disable it.

Python Setup Disabling Path Length Limit Pros and Cons?

when i&#39;m trying to perform ip command in ubuntu docker container, i&#39;m getting:

&gt; bash: ip: command not found.

ubuntu version:

    DISTRIB_ID=Ubuntu
    DISTRIB_RELEASE=18.04
    DISTRIB_CODENAME=bionic
    DISTRIB_DESCRIPTION=&quot;Ubuntu 18.04.1 LTS&quot;

what package should i install for that command?

Thanks

ip command is missing from ubuntu docker image

So Java 11 [is out][1]. Does anybody know how to install it (OpenJDK from Oracle) from the command line?

I would like to see something like it was before for Oracle Java 10:

    sudo add-apt-repository ppa:linuxuprising/java
    sudo apt-get update
    sudo apt-get install oracle-java10-installer

P. S. In the [similar][2] question proposed instruction:

    sudo apt-get install openjdk-11-jdk

doesn&#39;t work.


  [1]: https://mail.openjdk.java.net/pipermail/announce/2018-September/000257.html
  [2]: https://stackoverflow.com/questions/49507160/how-to-install-jdk-10-under-ubuntu

How to install JDK 11 under Ubuntu?

After freshly installing Ubuntu 18 I am receiving the following error when trying to launch a docker container that has a bind to a LVM (ext4) partition:

    mkdir /storage: read-only file system

I have tried reinstalling the OS, reinstalling Docker and forcing the drive to mount as RW (everything that isn&#39;t docker can write to the drive).

The directory that is being bound is currently set to 777 permissions.

There seems to be almost no information available for this error.

Docker - mkdir read-only file system

I tried to install [Yarn](https://yarnpkg.com/lang/en/) and when I used the `yarn` command I got:

    00h00m00s 0/0: : ERROR: There are no scenarios; must have at least one.

my `yarn --version` is `0.32`. Why doesn&#39;t it work?

Content Type	Original Author	Original Content on Stackoverflow
Question	user9885031	View Question on Stackoverflow
Solution 1 - Python	jc1850	View Answer on Stackoverflow
Solution 2 - Python	Bernhard	View Answer on Stackoverflow

How to upgrade Python version to 3.7?

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