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This article mainly explains "what are the Python problems encountered in the process of Tribler". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Now let the editor take you to learn "what are the Python problems encountered in the process of Tribler?"

[how to import packages]

If you get it done at two o'clock, you can import:

Package should have a _ _ init__.py file in its current directory, indicating that it is a package.

The parent directory of package should be in PYTHONPATH.

[path to open file and path to import module]

The path used to open the file is not the same as the path to the import module.

The path to open the file is the path where your main program file (.py) was started, and this current path is the only path that is determined, for example, when using PythonWin to open D:\ p2pEnv\ mainbranch\ Tribler\ Tools\ createlivestream.py:

Import osprint os.getcwd ()'D:\\ p2pEnv\\ mainbranch\\ Tribler\\ Tools'# can switch the current directory os.chdir (ritual C:\ Python27\ Lib') as follows

The path that the module searches for is through the path specified by sys.path, and this variable is initialized with the

Enter the directory where the script is located (that is, the current directory of the execution file)

PYTHONPATH directory

Python installation directory

The path added using sys.path.append (modulepath) is valid only at run time and will not exist the next time you run the compiler, where modulepath can be a zip or egg that contains files such as .py / pyc/pyo/pyw.

Import sysprint sys.path ['C:\\ WINDOWS\\ system32\\ python27.zip','C:\\ Python27\\ DLLs','C:\\ Python27\\ lib','C:\\ Python27\\ lib\\ plat-win','C:\\ Python27\\ lib\\ lib-tk','C:\ Python27\\ Lib\\ site-packages\ Pythonwin','C:\\ Python27' 'C:\\ Python27\\ lib\\ site-packages',' C:\\ Python27\\ lib\\ site-packages\\ win32','C:\\ Python27\\ lib\\ site-packages\\ win32\\ lib','C:\\ Python27\\ lib\\ site-packages\\ wx-2.8-msw-unicode']

[_ _ init__.py file]

_ _ init__.py file: this file is called before importing the package

As soon as any part of the package is imported for the first time, the code in the file _ _ init__.py is executed. This file can be empty, but it can also contain code that performs initialization specific to the package. During the execution of the import statement, all _ _ init__.py files encountered are executed. Therefore, the statement import Graphics.Primitive.fill will first execute the _ _ init__.py file in the Graphics directory, and then the _ _ init__.py file in the Primitive directory.

When using packages, you need to be careful when handling the following statement:

From Graphics.Primitive import *

Programmers who use this statement usually want to import all submodules associated with a package into the current namespace. However, due to different file name conventions among subsystems (especially in case sensitivity), Python cannot accurately determine the specific content of each module. As a result, the statement imports only all names defined in the _ _ init__.py file in the Primitive directory. This list should be defined in the package's _ _ init__.py file, for example:

# Graphics/Primitive/__init__.py__all__ = ["lines", "text", "fill"]

Therefore, the _ _ all__, can be defined in the _ _ init__.py file, through which the module (or package) can precisely control the imported name set, such as in module.py

_ _ all__ = ["bar", "SomeClassName", "SomeProperty", "SomeFunction"]

Importing the package name alone does not import the submodules contained in the package, such as

Import somepkgsomepkg.somemodule (xx) # failed

But because import somepkg executes the _ _ init__.py file in the somepkg directory, all if there is from in _ _ init__.py. Statements such as import somemodule, then somepkg.somemodule (xx) can be executed correctly.

[file format]

Python is not entirely an interpretive language, it is compiled. Python programs are usually executed by compiling the source .py file into .pyc or .pyo, and then executed by python's virtual machine. Compared to .py files, the compiled .pyc and .pyo are essentially not much different from .py, except that they increase the loading speed of the current module, but not the execution speed of the code. Usually, you don't have to actively compile a .py file. The document says that as long as import model is called, model.py will be automatically compiled to model.pyc and then loaded.

.pyc: precompiled .py file

.pyo: optimized precompiled .py file

.pyw:

Under Windows, .py files are run with python.exe, and .pyw files are run with pythonw.exe.

Compared with python.exe, pythonw.exe has the following differences:

The console window (also known as DOS window) does not pop up during execution.

All output to the original stdout and stderr is invalid

All reads from the original stdin will only get EOF

The .pyw format is designed to run developed programs with a pure graphical interface. Users of pure graphical interface programs do not need to see the console window.

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