I tried changing the python script from 2.7.11 to 3.6.0 on windows10

It was a concern that my home script was running on python2.7, so I tried python3. This year's work is safe, and I've done it, so I'm coding for New Year's Eve.

Prerequisites:

• python2.7.11 on windows10 --IDE is pycharm --There are 4 existing scripts, each with less than 100 lines, and what kind of processing is done will be described later.

Flow

0. Identify the target script ――I wonder if it's okay to use only the scripts that you usually use for temporary verification that you don't think you will use in the future.
1. Install python3.6 on windows -Download and install 3.6.0 from Download Python | Python.org --Checked Add PATH in the installation wizard --If you want to change what you want to refer to from cmd.exe, change the path from 2.7 to 3.6 from the advanced settings of windows.
2. Change pycharm settings --Create a new project for 3.6
3. Required package installation --I implemented it from pycharm, but maybe because it became py3, some changes on the windows side were necessary --Notes will be described later
4. Correct your own code --Move the required script as it is from the old project for py2 and fix and test the error part --Detailed changes will be described later
5. Execution path correction --Change what was referenced in Task Scheduler and tablacus explorer --The project path has changed because it was a new project.

What kind of processing was done and how was it handled (python2.7.11 → py3.6.0)

Since it is "in my case", it changes on a case-by-case basis depending on the writing style and the functions used, and it is not a story that I made it a good writing style as python3 at the level that it worked without problems.

Details of changes such as code correction

print statement

The one you often see.

# before
print "hoge"

#after
print("hoge")

Character code encoding

I don't need mysterious spells anymore.

# before
import sys
reload(sys)
sys.setdefaultencoding("cp932")

unicode(hoge_string, encoding='cp932')

#after
#I don't need spells anymore!However, if you write it, the way of writing the first two lines will change
import importlib
importlib.reload(sys)
sys.setdefaultencoding('cp932')

#You don't even need to specify each string variable
hoge_string

Message box display when using win32api

Use MessageBoxW instead of MessageBoxA. Reference: Call MessageBox (Windows API) from Python 3

# before
def win_alert(mes):
    user32 = windll.user32
    user32.MessageBoxA(
        0,
        mes,
        "info",
        0x00000040)

#after
def win_alert(mes):
    user32 = windll.user32
    user32.MessageBoxW(
        0,
        mes,
        "info",
        0x00000040)

xreadlines I couldn't find the official docs but xreadlines seems to be obsolete in python3. However, since there are readlines, I took x.

# before
for line in itr.xreadlines():

#after
for line in itr.readlines():

Reference: [Porting code to Python 3 using 2to3 --Dive Into Python 3 Japanese version](http://diveintopython3-ja.rdy.jp/porting-code-to-python-3-with-2to3. html)

Pillow installation

When I do "pip install pillow" on windows, I get angry that zlib is running during installation. Anyway, I got a pre-built binary and installed it.

#Open the following in your browser"Pillow‑3.4.2‑cp36‑cp36m‑win_amd64.whl"DL
#   http://www.lfd.uci.edu/~gohlke/pythonlibs/
$ pip install Pillow‑3.4.2‑cp36‑cp36m‑win_amd64.whl

Reference: [Can't install Pillow for Python 3.x in Windows --Zlib is required --Stack Overflow](http://stackoverflow.com/questions/38733647/cant-install-pillow-for-python-3-x- in-windows-zlib-is-required) Reference: python --Zlib error when installing Pillow --Stack Overflow Reference: http://www.lfd.uci.edu/~gohlke/pythonlibs/#pillow

numpy installation

According to the error at the time of installation, I installed "Visual C ++ Build Tools" and then re-executed it.

Reference: Download the Visual C ++ Build Tools (standalone C ++ compiler, libraries and tools)

(Bonus) Start python3 bottle from windows task scheduler but hide console

Even when using python2, the bottle web server was automatically started without displaying the console. But somehow pythonw.exe doesn't start the bottle script ... Of course, when you start it with python.exe, it will be displayed on the console ... (I forgot to back up the settings of the task scheduler and how it was realized ...)

So, after a quick search, if you select "Run regardless of whether the user is logged on" in the task scheduler, it will not be displayed. I was able to do it, but why not?

#Settings on the task scheduler
[General]→[Security options]
"Run regardless of whether the user is logged on"

[operation]→[program/script]
"C:\hoge\Python36\python.exe"

[operation]→[Add argument]
C:/hoge/bottle_sample.py

Note: [Batch file executed from Task Scheduler in Windows 7 does not appear on the screen. --Microsoft Community](https://answers.microsoft.com/en-us/windows/forum/windows_7-winapps/windows7%E3%81%A7%E3%82%BF%E3%82%B9%E3%82 % AF / ccff2c2f-5a0e-4f3d-ae81-9dff3e36fc3c)

in conclusion

Perhaps because the target was small and only simple functions, it took an hour or two in total even while investigating, so it was relatively easy to move. However, I'm not conscious of how to write it correctly as python3, so I have to study it properly ...

Especially for those who have a hard time in Japanese on windows, it is essential to upgrade to python3. (You don't have to use cp932 or mysterious character code anymore, or worry about the consistency match between encoding, decoding and unicode ())

Most of the libraries are already compatible. (If this is n times faster like ruby or php, it's gabung gabung)

that's all.