backwards-compatibility

Why is Python 3 not backwards compatible? [closed]

由 倾然丶 夕夏残阳落幕 提交于 2019-11-26 09:07:42
问题 I have learned that Python 3 is not backwards compatible. Will it not affect a lot of applications using older versions of Python? How did the developers of Python 3 not think it was absolutely necessary to make it backwards compatible? 回答1: Is Python 3.0 backward-compatible and why? Python 3.0 implements a lot of very useful features and breaks backward compatibility. It does it on purpose, so the great features can be implemented even despite the fact Python 2.x code may not work correctly

How to handle lack of JavaScript Object.bind() method in IE 8

由 只谈情不闲聊 提交于 2019-11-26 06:44:52
问题 I am writing a bit of JavaScript that uses the Object.bind method. funcabc = function(x, y, z){ this.myx = x; this.playUB = function(w) { if ( this.myx === null ) { // do blah blah return; } // do other stuff }; this.play = this.playUB.bind(this); }; Since I develop in WinXP with Firefox and sometimes test in Win7 with IE 9 or 10, I did not notice or pay attention to the fact that IE8 and below do not support bind . This particular script does not use the canvas, so I\'m a little hesitant to

How to install both Python 2.x and Python 3.x in Windows 7

由 |▌冷眼眸甩不掉的悲伤 提交于 2019-11-26 03:21:10
问题 I do most of my programming in Python 3.x on Windows 7, but now I need to use the Python Imaging Library (PIL), ImageMagick, and wxPython, all of which require Python 2.x. Can I have both Python 2.x and Python 3.x installed in Windows 7? When I run a script, how would I \"choose\" which version of Python should run it? Will the aforementioned programs be able to handle multiple versions of Python installed at once? I have searched for hours and hours for how to do this to no avail. Thanks.

Can I pass an array as arguments to a method with variable arguments in Java?

由 邮差的信 提交于 2019-11-26 00:10:07
问题 I\'d like to be able to create a function like: class A { private String extraVar; public String myFormat(String format, Object ... args){ return String.format(format, extraVar, args); } } The problem here is that args is treated as Object[] in the method myFormat , and thus is a single argument to String.format , while I\'d like every single Object in args to be passed as a new argument. Since String.format is also a method with variable arguments, this should be possible. If this is not

Python's many ways of string formatting — are the older ones (going to be) deprecated?

由 好久不见. 提交于 2019-11-25 23:49:18
问题 Python has at least six ways of formatting a string: In [1]: world = \"Earth\" # method 1a In [2]: \"Hello, %s\" % world Out[2]: \'Hello, Earth\' # method 1b In [3]: \"Hello, %(planet)s\" % {\"planet\": world} Out[3]: \'Hello, Earth\' # method 2a In [4]: \"Hello, {0}\".format(world) Out[4]: \'Hello, Earth\' # method 2b In [5]: \"Hello, {planet}\".format(planet=world) Out[5]: \'Hello, Earth\' # method 2c In [6]: f\"Hello, {world}\" Out[6]: \'Hello, Earth\' In [7]: from string import Template #

How to install both Python 2.x and Python 3.x in Windows 7

由 僤鯓⒐⒋嵵緔 提交于 2019-11-25 20:09:54
I do most of my programming in Python 3.x on Windows 7, but now I need to use the Python Imaging Library (PIL), ImageMagick, and wxPython, all of which require Python 2.x. Can I have both Python 2.x and Python 3.x installed in Windows 7? When I run a script, how would I "choose" which version of Python should run it? Will the aforementioned programs be able to handle multiple versions of Python installed at once? I have searched for hours and hours for how to do this to no avail. Thanks. I found that the formal way to do this is as follows: Just install two (or more, using their installers)

Python's many ways of string formatting — are the older ones (going to be) deprecated?

由 血红的双手。 提交于 2019-11-25 19:13:15
Python has at least six ways of formatting a string: In [1]: world = "Earth" # method 1a In [2]: "Hello, %s" % world Out[2]: 'Hello, Earth' # method 1b In [3]: "Hello, %(planet)s" % {"planet": world} Out[3]: 'Hello, Earth' # method 2a In [4]: "Hello, {0}".format(world) Out[4]: 'Hello, Earth' # method 2b In [5]: "Hello, {planet}".format(planet=world) Out[5]: 'Hello, Earth' # method 2c In [6]: f"Hello, {world}" Out[6]: 'Hello, Earth' In [7]: from string import Template # method 3 In [8]: Template("Hello, $planet").substitute(planet=world) Out[8]: 'Hello, Earth' A brief history of the different
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