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# SOME DESCRIPTIVE TITLE.
# Copyright (C) 2001 Python Software Foundation
# This file is distributed under the same license as the Python package.
# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
#
# Translators:
# python-doc bot, 2025
#
#, fuzzy
msgid ""
msgstr ""
"Project-Id-Version: Python 3.14\n"
"Report-Msgid-Bugs-To: \n"
"POT-Creation-Date: 2026-08-22 12:07+0200\n"
"PO-Revision-Date: 2025-09-16 00:00+0000\n"
"Last-Translator: python-doc bot, 2025\n"
"Language-Team: German (https://app.transifex.com/python-doc/teams/5390/de/)\n"
"Language: de\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"
"Plural-Forms: nplurals=2; plural=(n != 1);\n"
#: ../../faq/programming.rst:5
msgid "Programming FAQ"
msgstr ""
#: ../../faq/programming.rst:8
msgid "Contents"
msgstr "Inhalt"
#: ../../faq/programming.rst:12
msgid "General questions"
msgstr ""
#: ../../faq/programming.rst:15
msgid ""
"Is there a source code-level debugger with breakpoints and single-stepping?"
msgstr ""
#: ../../faq/programming.rst:17 ../../faq/programming.rst:56
msgid "Yes."
msgstr ""
#: ../../faq/programming.rst:19
msgid ""
"Several debuggers for Python are described below, and the built-in function :"
"func:`breakpoint` allows you to drop into any of them."
msgstr ""
#: ../../faq/programming.rst:22
msgid ""
"The pdb module is a simple but adequate console-mode debugger for Python. It "
"is part of the standard Python library, and is :mod:`documented in the "
"Library Reference Manual <pdb>`. You can also write your own debugger by "
"using the code for pdb as an example."
msgstr ""
#: ../../faq/programming.rst:27
msgid ""
"The IDLE interactive development environment, which is part of the standard "
"Python distribution (normally available as :mod:`idlelib`), includes a "
"graphical debugger."
msgstr ""
#: ../../faq/programming.rst:31
msgid ""
"PythonWin is a Python IDE that includes a GUI debugger based on pdb. The "
"PythonWin debugger colors breakpoints and has quite a few cool features such "
"as debugging non-PythonWin programs. PythonWin is available as part of "
"`pywin32 <https://github.com/mhammond/pywin32>`_ project and as a part of "
"the `ActivePython <https://www.activestate.com/products/python/>`_ "
"distribution."
msgstr ""
#: ../../faq/programming.rst:38
msgid ""
"`Eric <https://eric-ide.python-projects.org/>`_ is an IDE built on PyQt and "
"the Scintilla editing component."
msgstr ""
#: ../../faq/programming.rst:41
msgid ""
"`trepan3k <https://github.com/rocky/python3-trepan/>`_ is a gdb-like "
"debugger."
msgstr ""
#: ../../faq/programming.rst:43
msgid ""
"`Visual Studio Code <https://code.visualstudio.com/>`_ is an IDE with "
"debugging tools that integrates with version-control software."
msgstr ""
#: ../../faq/programming.rst:46
msgid ""
"There are a number of commercial Python IDEs that include graphical "
"debuggers. They include:"
msgstr ""
#: ../../faq/programming.rst:49
msgid "`Wing IDE <https://wingware.com/>`_"
msgstr ""
#: ../../faq/programming.rst:50
msgid "`PyCharm <https://www.jetbrains.com/pycharm/>`_"
msgstr ""
#: ../../faq/programming.rst:54
msgid "Are there tools to help find bugs or perform static analysis?"
msgstr ""
#: ../../faq/programming.rst:58
msgid ""
"`Ruff <https://docs.astral.sh/ruff/>`__, `Pylint <https://pylint.readthedocs."
"io/>`__ and `Pyflakes <https://github.com/PyCQA/pyflakes>`__ do basic "
"checking that will help you catch bugs sooner."
msgstr ""
#: ../../faq/programming.rst:63
msgid ""
"Static type checkers such as `mypy <https://mypy-lang.org/>`__, `ty <https://"
"docs.astral.sh/ty/>`__, `Pyrefly <https://pyrefly.org/>`__, and `pytype "
"<https://github.com/google/pytype>`__ can check type hints in Python source "
"code."
msgstr ""
#: ../../faq/programming.rst:73
msgid "How can I create a stand-alone binary from a Python script?"
msgstr ""
#: ../../faq/programming.rst:75
msgid ""
"You don't need the ability to compile Python to C code if all you want is a "
"stand-alone program that users can download and run without having to "
"install the Python distribution first. There are a number of tools that "
"determine the set of modules required by a program and bind these modules "
"together with a Python binary to produce a single executable."
msgstr ""
#: ../../faq/programming.rst:81
msgid ""
"One is to use the freeze tool, which is included in the Python source tree "
"as :source:`Tools/freeze`. It converts Python byte code to C arrays; with a "
"C compiler you can embed all your modules into a new program, which is then "
"linked with the standard Python modules."
msgstr ""
#: ../../faq/programming.rst:87
msgid ""
"It works by scanning your source recursively for import statements (in both "
"forms) and looking for the modules in the standard Python path as well as in "
"the source directory (for built-in modules). It then turns the bytecode for "
"modules written in Python into C code (array initializers that can be turned "
"into code objects using the marshal module) and creates a custom-made config "
"file that only contains those built-in modules which are actually used in "
"the program. It then compiles the generated C code and links it with the "
"rest of the Python interpreter to form a self-contained binary which acts "
"exactly like your script."
msgstr ""
#: ../../faq/programming.rst:96
msgid ""
"The following packages can help with the creation of console and GUI "
"executables:"
msgstr ""
#: ../../faq/programming.rst:99
msgid "`Nuitka <https://nuitka.net/>`_ (Cross-platform)"
msgstr ""
#: ../../faq/programming.rst:100
msgid "`PyInstaller <https://pyinstaller.org/>`_ (Cross-platform)"
msgstr ""
#: ../../faq/programming.rst:101
msgid ""
"`PyOxidizer <https://pyoxidizer.readthedocs.io/en/stable/>`_ (Cross-platform)"
msgstr ""
#: ../../faq/programming.rst:102
msgid ""
"`cx_Freeze <https://marcelotduarte.github.io/cx_Freeze/>`_ (Cross-platform)"
msgstr ""
#: ../../faq/programming.rst:103
msgid "`py2app <https://github.com/ronaldoussoren/py2app>`_ (macOS only)"
msgstr ""
#: ../../faq/programming.rst:104
msgid "`py2exe <https://www.py2exe.org/>`_ (Windows only)"
msgstr ""
#: ../../faq/programming.rst:108
msgid "Are there coding standards or a style guide for Python programs?"
msgstr ""
#: ../../faq/programming.rst:110
msgid ""
"Yes. The coding style required for standard library modules is documented "
"as :pep:`8`."
msgstr ""
#: ../../faq/programming.rst:115
msgid "Core language"
msgstr ""
#: ../../faq/programming.rst:120
msgid "Why am I getting an UnboundLocalError when the variable has a value?"
msgstr ""
#: ../../faq/programming.rst:122
msgid ""
"It can be a surprise to get the :exc:`UnboundLocalError` in previously "
"working code when it is modified by adding an assignment statement somewhere "
"in the body of a function."
msgstr ""
#: ../../faq/programming.rst:126
msgid "This code:"
msgstr ""
#: ../../faq/programming.rst:135
msgid "works, but this code:"
msgstr ""
#: ../../faq/programming.rst:142
msgid "results in an :exc:`!UnboundLocalError`:"
msgstr ""
#: ../../faq/programming.rst:149
msgid ""
"This is because when you make an assignment to a variable in a scope, that "
"variable becomes local to that scope and shadows any similarly named "
"variable in the outer scope. Since the last statement in foo assigns a new "
"value to ``x``, the compiler recognizes it as a local variable. "
"Consequently when the earlier ``print(x)`` attempts to print the "
"uninitialized local variable and an error results."
msgstr ""
#: ../../faq/programming.rst:156
msgid ""
"In the example above you can access the outer scope variable by declaring it "
"global:"
msgstr ""
#: ../../faq/programming.rst:168
msgid ""
"This explicit declaration is required in order to remind you that (unlike "
"the superficially analogous situation with class and instance variables) you "
"are actually modifying the value of the variable in the outer scope:"
msgstr ""
#: ../../faq/programming.rst:175
msgid ""
"You can do a similar thing in a nested scope using the :keyword:`nonlocal` "
"keyword:"
msgstr ""
#: ../../faq/programming.rst:193
msgid "What are the rules for local and global variables in Python?"
msgstr ""
#: ../../faq/programming.rst:195
msgid ""
"In Python, variables that are only referenced inside a function are "
"implicitly global. If a variable is assigned a value anywhere within the "
"function's body, it's assumed to be a local unless explicitly declared as "
"global."
msgstr ""
#: ../../faq/programming.rst:199
msgid ""
"Though a bit surprising at first, a moment's consideration explains this. "
"On one hand, requiring :keyword:`global` for assigned variables provides a "
"bar against unintended side-effects. On the other hand, if ``global`` was "
"required for all global references, you'd be using ``global`` all the time. "
"You'd have to declare as global every reference to a built-in function or to "
"a component of an imported module. This clutter would defeat the usefulness "
"of the ``global`` declaration for identifying side-effects."
msgstr ""
#: ../../faq/programming.rst:209
msgid ""
"Why do lambdas defined in a loop with different values all return the same "
"result?"
msgstr ""
#: ../../faq/programming.rst:211
msgid ""
"Assume you use a for loop to define a few different lambdas (or even plain "
"functions), for example::"
msgstr ""
#: ../../faq/programming.rst:214
msgid ""
">>> squares = []\n"
">>> for x in range(5):\n"
"... squares.append(lambda: x**2)"
msgstr ""
#: ../../faq/programming.rst:218
msgid ""
"This gives you a list that contains 5 lambdas that calculate ``x**2``. You "
"might expect that, when called, they would return, respectively, ``0``, "
"``1``, ``4``, ``9``, and ``16``. However, when you actually try you will "
"see that they all return ``16``::"
msgstr ""
#: ../../faq/programming.rst:223
msgid ""
">>> squares[2]()\n"
"16\n"
">>> squares[4]()\n"
"16"
msgstr ""
#: ../../faq/programming.rst:228
msgid ""
"This happens because ``x`` is not local to the lambdas, but is defined in "
"the outer scope, and it is accessed when the lambda is called --- not when "
"it is defined. At the end of the loop, the value of ``x`` is ``4``, so all "
"the functions now return ``4**2``, that is ``16``. You can also verify this "
"by changing the value of ``x`` and see how the results of the lambdas "
"change::"
msgstr ""
#: ../../faq/programming.rst:234
msgid ""
">>> x = 8\n"
">>> squares[2]()\n"
"64"
msgstr ""
#: ../../faq/programming.rst:238
msgid ""
"In order to avoid this, you need to save the values in variables local to "
"the lambdas, so that they don't rely on the value of the global ``x``::"
msgstr ""
#: ../../faq/programming.rst:241
msgid ""
">>> squares = []\n"
">>> for x in range(5):\n"
"... squares.append(lambda n=x: n**2)"
msgstr ""
#: ../../faq/programming.rst:245
msgid ""
"Here, ``n=x`` creates a new variable ``n`` local to the lambda and computed "
"when the lambda is defined so that it has the same value that ``x`` had at "
"that point in the loop. This means that the value of ``n`` will be ``0`` in "
"the first lambda, ``1`` in the second, ``2`` in the third, and so on. "
"Therefore each lambda will now return the correct result::"
msgstr ""
#: ../../faq/programming.rst:251
msgid ""
">>> squares[2]()\n"
"4\n"
">>> squares[4]()\n"
"16"
msgstr ""
#: ../../faq/programming.rst:256
msgid ""
"Note that this behaviour is not peculiar to lambdas, but applies to regular "
"functions too."
msgstr ""
#: ../../faq/programming.rst:261
msgid "How do I share global variables across modules?"
msgstr ""
#: ../../faq/programming.rst:263
msgid ""
"The canonical way to share information across modules within a single "
"program is to create a special module (often called config or cfg). Just "
"import the config module in all modules of your application; the module then "
"becomes available as a global name. Because there is only one instance of "
"each module, any changes made to the module object get reflected "
"everywhere. For example:"
msgstr ""
#: ../../faq/programming.rst:269
msgid "config.py::"
msgstr ""
#: ../../faq/programming.rst:271
msgid "x = 0 # Default value of the 'x' configuration setting"
msgstr ""
#: ../../faq/programming.rst:273
msgid "mod.py::"
msgstr ""
#: ../../faq/programming.rst:275
msgid ""
"import config\n"
"config.x = 1"
msgstr ""
#: ../../faq/programming.rst:278
msgid "main.py::"
msgstr ""
#: ../../faq/programming.rst:280
msgid ""
"import config\n"
"import mod\n"
"print(config.x)"
msgstr ""
#: ../../faq/programming.rst:284
msgid ""
"Note that using a module is also the basis for implementing the singleton "
"design pattern, for the same reason."
msgstr ""
#: ../../faq/programming.rst:289
msgid "What are the \"best practices\" for using import in a module?"
msgstr ""
#: ../../faq/programming.rst:291
msgid ""
"In general, don't use ``from modulename import *``. Doing so clutters the "
"importer's namespace, and makes it much harder for linters to detect "
"undefined names."
msgstr ""
#: ../../faq/programming.rst:295
msgid ""
"Import modules at the top of a file. Doing so makes it clear what other "
"modules your code requires and avoids questions of whether the module name "
"is in scope. Using one import per line makes it easy to add and delete "
"module imports, but using multiple imports per line uses less screen space."
msgstr ""
#: ../../faq/programming.rst:300
msgid "It's good practice if you import modules in the following order:"
msgstr ""
#: ../../faq/programming.rst:302
msgid ""
"standard library modules -- such as :mod:`sys`, :mod:`os`, :mod:`argparse`, :"
"mod:`re`"
msgstr ""
#: ../../faq/programming.rst:303
msgid ""
"third-party library modules (anything installed in Python's site-packages "
"directory) -- such as :pypi:`dateutil`, :pypi:`requests`, :pypi:`tzdata`"
msgstr ""
#: ../../faq/programming.rst:305
msgid "locally developed modules"
msgstr ""
#: ../../faq/programming.rst:307
msgid ""
"It is sometimes necessary to move imports to a function or class to avoid "
"problems with circular imports. Gordon McMillan says:"
msgstr ""
#: ../../faq/programming.rst:310
msgid ""
"Circular imports are fine where both modules use the \"import <module>\" "
"form of import. They fail when the 2nd module wants to grab a name out of "
"the first (\"from module import name\") and the import is at the top level. "
"That's because names in the 1st are not yet available, because the first "
"module is busy importing the 2nd."
msgstr ""
#: ../../faq/programming.rst:316
msgid ""
"In this case, if the second module is only used in one function, then the "
"import can easily be moved into that function. By the time the import is "
"called, the first module will have finished initializing, and the second "
"module can do its import."
msgstr ""
#: ../../faq/programming.rst:321
msgid ""
"It may also be necessary to move imports out of the top level of code if "
"some of the modules are platform-specific. In that case, it may not even be "
"possible to import all of the modules at the top of the file. In this case, "
"importing the correct modules in the corresponding platform-specific code is "
"a good option."
msgstr ""
#: ../../faq/programming.rst:326
msgid ""
"Only move imports into a local scope, such as inside a function definition, "
"if it's necessary to solve a problem such as avoiding a circular import or "
"are trying to reduce the initialization time of a module. This technique is "
"especially helpful if many of the imports are unnecessary depending on how "
"the program executes. You may also want to move imports into a function if "
"the modules are only ever used in that function. Note that loading a module "
"the first time may be expensive because of the one time initialization of "
"the module, but loading a module multiple times is virtually free, costing "
"only a couple of dictionary lookups. Even if the module name has gone out "
"of scope, the module is probably available in :data:`sys.modules`."
msgstr ""
#: ../../faq/programming.rst:339
msgid "Why are default values shared between objects?"
msgstr ""
#: ../../faq/programming.rst:341
msgid ""
"This type of bug commonly bites neophyte programmers. Consider this "
"function::"
msgstr ""
#: ../../faq/programming.rst:343
msgid ""
"def foo(mydict={}): # Danger: shared reference to one dict for all calls\n"
" ... compute something ...\n"
" mydict[key] = value\n"
" return mydict"
msgstr ""
#: ../../faq/programming.rst:348
msgid ""
"The first time you call this function, ``mydict`` contains a single item. "
"The second time, ``mydict`` contains two items because when ``foo()`` begins "
"executing, ``mydict`` starts out with an item already in it."
msgstr ""
#: ../../faq/programming.rst:352
msgid ""
"It is often expected that a function call creates new objects for default "
"values. This is not what happens. Default values are created exactly once, "
"when the function is defined. If that object is changed, like the "
"dictionary in this example, subsequent calls to the function will refer to "
"this changed object."
msgstr ""
#: ../../faq/programming.rst:357
msgid ""
"By definition, immutable objects such as numbers, strings, tuples, and "
"``None``, are safe from change. Changes to mutable objects such as "
"dictionaries, lists, and class instances can lead to confusion."
msgstr ""
#: ../../faq/programming.rst:361
msgid ""
"Because of this feature, it is good programming practice to not use mutable "
"objects as default values. Instead, use ``None`` as the default value and "
"inside the function, check if the parameter is ``None`` and create a new "
"list/dictionary/whatever if it is. For example, don't write::"
msgstr ""
#: ../../faq/programming.rst:366
msgid ""
"def foo(mydict={}):\n"
" ..."
msgstr ""
#: ../../faq/programming.rst:369
msgid "but::"
msgstr ""
#: ../../faq/programming.rst:371
msgid ""
"def foo(mydict=None):\n"
" if mydict is None:\n"
" mydict = {} # create a new dict for local namespace"
msgstr ""
#: ../../faq/programming.rst:375
msgid ""
"This feature can be useful. When you have a function that's time-consuming "
"to compute, a common technique is to cache the parameters and the resulting "
"value of each call to the function, and return the cached value if the same "
"value is requested again. This is called \"memoizing\", and can be "
"implemented like this::"
msgstr ""
#: ../../faq/programming.rst:380
msgid ""
"# Callers can only provide two parameters and optionally pass _cache by "
"keyword\n"
"def expensive(arg1, arg2, *, _cache={}):\n"
" if (arg1, arg2) in _cache:\n"
" return _cache[(arg1, arg2)]\n"
"\n"
" # Calculate the value\n"
" result = ... expensive computation ...\n"
" _cache[(arg1, arg2)] = result # Store result in the cache\n"
" return result"
msgstr ""
#: ../../faq/programming.rst:390
msgid ""
"You could use a global variable containing a dictionary instead of the "
"default value; it's a matter of taste."
msgstr ""
#: ../../faq/programming.rst:395
msgid ""
"How can I pass optional or keyword parameters from one function to another?"
msgstr ""
#: ../../faq/programming.rst:397
msgid ""
"Collect the arguments using the ``*`` and ``**`` specifiers in the "
"function's parameter list; this gives you the positional arguments as a "
"tuple and the keyword arguments as a dictionary. You can then pass these "
"arguments when calling another function by using ``*`` and ``**``::"
msgstr ""
#: ../../faq/programming.rst:402
msgid ""
"def f(x, *args, **kwargs):\n"
" ...\n"
" kwargs['width'] = '14.3c'\n"
" ...\n"
" g(x, *args, **kwargs)"
msgstr ""
#: ../../faq/programming.rst:416
msgid "What is the difference between arguments and parameters?"
msgstr ""
#: ../../faq/programming.rst:418
msgid ""
":term:`Parameters <parameter>` are defined by the names that appear in a "
"function definition, whereas :term:`arguments <argument>` are the values "
"actually passed to a function when calling it. Parameters define what :term:"
"`kind of arguments <parameter>` a function can accept. For example, given "
"the function definition::"
msgstr ""
#: ../../faq/programming.rst:424
msgid ""
"def func(foo, bar=None, **kwargs):\n"
" pass"
msgstr ""
#: ../../faq/programming.rst:427
msgid ""
"*foo*, *bar* and *kwargs* are parameters of ``func``. However, when calling "
"``func``, for example::"
msgstr ""
#: ../../faq/programming.rst:430
msgid "func(42, bar=314, extra=somevar)"
msgstr ""
#: ../../faq/programming.rst:432
msgid "the values ``42``, ``314``, and ``somevar`` are arguments."
msgstr ""
#: ../../faq/programming.rst:436
msgid "Why did changing list 'y' also change list 'x'?"
msgstr ""
#: ../../faq/programming.rst:438
msgid "If you wrote code like::"
msgstr ""
#: ../../faq/programming.rst:440
msgid ""
">>> x = []\n"
">>> y = x\n"
">>> y.append(10)\n"
">>> y\n"
"[10]\n"
">>> x\n"
"[10]"
msgstr ""
#: ../../faq/programming.rst:448
msgid ""
"you might be wondering why appending an element to ``y`` changed ``x`` too."
msgstr ""
#: ../../faq/programming.rst:450
msgid "There are two factors that produce this result:"
msgstr ""
#: ../../faq/programming.rst:452
msgid ""
"Variables are simply names that refer to objects. Doing ``y = x`` doesn't "
"create a copy of the list -- it creates a new variable ``y`` that refers to "
"the same object ``x`` refers to. This means that there is only one object "
"(the list), and both ``x`` and ``y`` refer to it."
msgstr ""
#: ../../faq/programming.rst:456
msgid ""
"Lists are :term:`mutable`, which means that you can change their content."
msgstr ""
#: ../../faq/programming.rst:458
msgid ""
"After the call to :meth:`~sequence.append`, the content of the mutable "
"object has changed from ``[]`` to ``[10]``. Since both the variables refer "
"to the same object, using either name accesses the modified value ``[10]``."
msgstr ""
#: ../../faq/programming.rst:462
msgid "If we instead assign an immutable object to ``x``::"
msgstr ""
#: ../../faq/programming.rst:464
msgid ""
">>> x = 5 # ints are immutable\n"
">>> y = x\n"
">>> x = x + 1 # 5 can't be mutated, we are creating a new object here\n"
">>> x\n"
"6\n"
">>> y\n"
"5"
msgstr ""
#: ../../faq/programming.rst:472
msgid ""
"we can see that in this case ``x`` and ``y`` are not equal anymore. This is "
"because integers are :term:`immutable`, and when we do ``x = x + 1`` we are "
"not mutating the int ``5`` by incrementing its value; instead, we are "
"creating a new object (the int ``6``) and assigning it to ``x`` (that is, "
"changing which object ``x`` refers to). After this assignment we have two "
"objects (the ints ``6`` and ``5``) and two variables that refer to them "
"(``x`` now refers to ``6`` but ``y`` still refers to ``5``)."
msgstr ""
#: ../../faq/programming.rst:480
msgid ""
"Some operations (for example ``y.append(10)`` and ``y.sort()``) mutate the "
"object, whereas superficially similar operations (for example ``y = y + "
"[10]`` and :func:`sorted(y) <sorted>`) create a new object. In general in "
"Python (and in all cases in the standard library) a method that mutates an "
"object will return ``None`` to help avoid getting the two types of "
"operations confused. So if you mistakenly write ``y.sort()`` thinking it "
"will give you a sorted copy of ``y``, you'll instead end up with ``None``, "
"which will likely cause your program to generate an easily diagnosed error."
msgstr ""
#: ../../faq/programming.rst:489
msgid ""
"However, there is one class of operations where the same operation sometimes "
"has different behaviors with different types: the augmented assignment "
"operators. For example, ``+=`` mutates lists but not tuples or ints "
"(``a_list += [1, 2, 3]`` is equivalent to ``a_list.extend([1, 2, 3])`` and "
"mutates ``a_list``, whereas ``some_tuple += (1, 2, 3)`` and ``some_int += "
"1`` create new objects)."
msgstr ""
#: ../../faq/programming.rst:496
msgid "In other words:"
msgstr ""
#: ../../faq/programming.rst:498
msgid ""
"If we have a mutable object (such as :class:`list`, :class:`dict`, :class:"
"`set`), we can use some specific operations to mutate it and all the "
"variables that refer to it will see the change."
msgstr ""
#: ../../faq/programming.rst:501
msgid ""
"If we have an immutable object (such as :class:`str`, :class:`int`, :class:"
"`tuple`), all the variables that refer to it will always see the same value, "
"but operations that transform that value into a new value always return a "
"new object."
msgstr ""
#: ../../faq/programming.rst:506
msgid ""
"If you want to know if two variables refer to the same object or not, you "
"can use the :keyword:`is` operator, or the built-in function :func:`id`."
msgstr ""
#: ../../faq/programming.rst:511
msgid "How do I write a function with output parameters (call by reference)?"
msgstr ""
#: ../../faq/programming.rst:513
msgid ""
"Remember that arguments are passed by assignment in Python. Since "
"assignment just creates references to objects, there's no alias between an "
"argument name in the caller and callee, and consequently no call-by-"
"reference. You can achieve the desired effect in a number of ways."
msgstr ""
#: ../../faq/programming.rst:518
msgid "By returning a tuple of the results::"
msgstr ""
#: ../../faq/programming.rst:520
msgid ""
">>> def func1(a, b):\n"
"... a = 'new-value' # a and b are local names\n"
"... b = b + 1 # assigned to new objects\n"
"... return a, b # return new values\n"
"...\n"
">>> x, y = 'old-value', 99\n"
">>> func1(x, y)\n"
"('new-value', 100)"
msgstr ""
#: ../../faq/programming.rst:529
msgid "This is almost always the clearest solution."
msgstr ""
#: ../../faq/programming.rst:531
msgid ""
"By using global variables. This isn't thread-safe, and is not recommended."
msgstr ""
#: ../../faq/programming.rst:533
msgid "By passing a mutable (changeable in-place) object::"
msgstr ""
#: ../../faq/programming.rst:535
msgid ""
">>> def func2(a):\n"
"... a[0] = 'new-value' # 'a' references a mutable list\n"
"... a[1] = a[1] + 1 # changes a shared object\n"
"...\n"
">>> args = ['old-value', 99]\n"
">>> func2(args)\n"
">>> args\n"
"['new-value', 100]"
msgstr ""
#: ../../faq/programming.rst:544
msgid "By passing in a dictionary that gets mutated::"
msgstr ""
#: ../../faq/programming.rst:546
msgid ""
">>> def func3(args):\n"
"... args['a'] = 'new-value' # args is a mutable dictionary\n"
"... args['b'] = args['b'] + 1 # change it in-place\n"
"...\n"
">>> args = {'a': 'old-value', 'b': 99}\n"
">>> func3(args)\n"
">>> args\n"
"{'a': 'new-value', 'b': 100}"
msgstr ""
#: ../../faq/programming.rst:555
msgid "Or bundle up values in a class instance::"
msgstr ""
#: ../../faq/programming.rst:557
msgid ""
">>> class Namespace:\n"
"... def __init__(self, /, **args):\n"
"... for key, value in args.items():\n"
"... setattr(self, key, value)\n"
"...\n"
">>> def func4(args):\n"
"... args.a = 'new-value' # args is a mutable Namespace\n"
"... args.b = args.b + 1 # change object in-place\n"
"...\n"
">>> args = Namespace(a='old-value', b=99)\n"
">>> func4(args)\n"
">>> vars(args)\n"
"{'a': 'new-value', 'b': 100}"
msgstr ""
#: ../../faq/programming.rst:572
msgid "There's almost never a good reason to get this complicated."
msgstr ""
#: ../../faq/programming.rst:574
msgid "Your best choice is to return a tuple containing the multiple results."
msgstr ""
#: ../../faq/programming.rst:578
msgid "How do you make a higher order function in Python?"
msgstr ""
#: ../../faq/programming.rst:580
msgid ""
"You have two choices: you can use nested scopes or you can use callable "
"objects. For example, suppose you wanted to define ``linear(a,b)`` which "
"returns a function ``f(x)`` that computes the value ``a*x+b``. Using nested "
"scopes::"
msgstr ""
#: ../../faq/programming.rst:584
msgid ""
"def linear(a, b):\n"
" def result(x):\n"
" return a * x + b\n"
" return result"
msgstr ""
#: ../../faq/programming.rst:589
msgid "Or using a callable object::"
msgstr ""
#: ../../faq/programming.rst:591
msgid ""
"class linear:\n"
"\n"
" def __init__(self, a, b):\n"
" self.a, self.b = a, b\n"
"\n"
" def __call__(self, x):\n"
" return self.a * x + self.b"
msgstr ""
#: ../../faq/programming.rst:599
msgid "In both cases, ::"
msgstr ""
#: ../../faq/programming.rst:601
msgid "taxes = linear(0.3, 2)"
msgstr ""
#: ../../faq/programming.rst:603
msgid "gives a callable object where ``taxes(10e6) == 0.3 * 10e6 + 2``."
msgstr ""
#: ../../faq/programming.rst:605
msgid ""
"The callable object approach has the disadvantage that it is a bit slower "
"and results in slightly longer code. However, note that a collection of "
"callables can share their signature via inheritance::"
msgstr ""
#: ../../faq/programming.rst:609
msgid ""
"class exponential(linear):\n"
" # __init__ inherited\n"
" def __call__(self, x):\n"
" return self.a * (x ** self.b)"
msgstr ""
#: ../../faq/programming.rst:614
msgid "Object can encapsulate state for several methods::"
msgstr ""
#: ../../faq/programming.rst:616
msgid ""
"class counter:\n"
"\n"
" value = 0\n"
"\n"
" def set(self, x):\n"
" self.value = x\n"
"\n"
" def up(self):\n"
" self.value = self.value + 1\n"
"\n"
" def down(self):\n"
" self.value = self.value - 1\n"
"\n"
"count = counter()\n"
"inc, dec, reset = count.up, count.down, count.set"
msgstr ""
#: ../../faq/programming.rst:632
msgid ""
"Here ``inc()``, ``dec()`` and ``reset()`` act like functions which share the "
"same counting variable."
msgstr ""
#: ../../faq/programming.rst:637
msgid "How do I copy an object in Python?"
msgstr ""
#: ../../faq/programming.rst:639
msgid ""
"In general, try :func:`copy.copy` or :func:`copy.deepcopy` for the general "
"case. Not all objects can be copied, but most can."
msgstr ""
#: ../../faq/programming.rst:642
msgid ""
"Some objects can be copied more easily. Dictionaries have a :meth:`~dict."
"copy` method::"
msgstr ""
#: ../../faq/programming.rst:645
msgid "newdict = olddict.copy()"
msgstr ""
#: ../../faq/programming.rst:647
msgid "Sequences can be copied by slicing::"
msgstr ""
#: ../../faq/programming.rst:649
msgid "new_l = l[:]"
msgstr ""
#: ../../faq/programming.rst:653
msgid "How can I find the methods or attributes of an object?"
msgstr ""
#: ../../faq/programming.rst:655
msgid ""
"For an instance ``x`` of a user-defined class, :func:`dir(x) <dir>` returns "
"an alphabetized list of the names containing the instance attributes and "
"methods and attributes defined by its class."
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