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1517 lines (1291 loc) · 44.1 KB
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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:
# Bhuvansh Kataria, 2026
#
#, fuzzy
msgid ""
msgstr ""
"Project-Id-Version: Python 3.15\n"
"Report-Msgid-Bugs-To: \n"
"POT-Creation-Date: 2026-07-29 15:50+0000\n"
"PO-Revision-Date: 2025-09-16 00:02+0000\n"
"Last-Translator: Bhuvansh Kataria, 2026\n"
"Language-Team: Panjabi (Punjabi) (https://app.transifex.com/python-doc/"
"teams/5390/pa/)\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"
"Language: pa\n"
"Plural-Forms: nplurals=2; plural=(n != 1);\n"
msgid "More Control Flow Tools"
msgstr ""
msgid ""
"As well as the :keyword:`while` statement just introduced, Python uses a few "
"more that we will encounter in this chapter."
msgstr ""
msgid ":keyword:`!if` Statements"
msgstr ""
msgid ""
"Perhaps the most well-known statement type is the :keyword:`if` statement. "
"For example::"
msgstr ""
msgid ""
">>> x = int(input(\"Please enter an integer: \"))\n"
"Please enter an integer: 42\n"
">>> if x < 0:\n"
"... x = 0\n"
"... print('Negative changed to zero')\n"
"... elif x == 0:\n"
"... print('Zero')\n"
"... elif x == 1:\n"
"... print('Single')\n"
"... else:\n"
"... print('More')\n"
"...\n"
"More"
msgstr ""
msgid ""
"There can be zero or more :keyword:`elif` parts, and the :keyword:`else` "
"part is optional. The keyword ':keyword:`!elif`' is short for 'else if', "
"and is useful to avoid excessive indentation. An :keyword:`!if` ... :"
"keyword:`!elif` ... :keyword:`!elif` ... sequence is a substitute for the "
"``switch`` or ``case`` statements found in other languages."
msgstr ""
msgid ""
"If you're comparing the same value to several constants, or checking for "
"specific types or attributes, you may also find the :keyword:`!match` "
"statement useful. For more details see :ref:`tut-match`."
msgstr ""
msgid ":keyword:`!for` Statements"
msgstr ""
msgid ""
"The :keyword:`for` statement in Python differs a bit from what you may be "
"used to in C or Pascal. Rather than always iterating over an arithmetic "
"progression of numbers (like in Pascal), or giving the user the ability to "
"define both the iteration step and halting condition (as C), Python's :"
"keyword:`!for` statement iterates over the items of any sequence (a list or "
"a string), in the order that they appear in the sequence. For example (no "
"pun intended):"
msgstr ""
msgid ""
">>> # Measure some strings:\n"
">>> words = ['cat', 'window', 'defenestrate']\n"
">>> for w in words:\n"
"... print(w, len(w))\n"
"...\n"
"cat 3\n"
"window 6\n"
"defenestrate 12"
msgstr ""
msgid ""
"Code that modifies a collection while iterating over that same collection "
"can be tricky to get right. Instead, it is usually more straight-forward to "
"loop over a copy of the collection or to create a new collection::"
msgstr ""
msgid ""
"# Create a sample collection\n"
"users = {'Hans': 'active', 'Éléonore': 'inactive', '景太郎': 'active'}\n"
"\n"
"# Strategy: Iterate over a copy\n"
"for user, status in users.copy().items():\n"
" if status == 'inactive':\n"
" del users[user]\n"
"\n"
"# Strategy: Create a new collection\n"
"active_users = {}\n"
"for user, status in users.items():\n"
" if status == 'active':\n"
" active_users[user] = status"
msgstr ""
msgid "The :func:`range` Function"
msgstr ""
msgid ""
"If you do need to iterate over a sequence of numbers, the built-in function :"
"func:`range` comes in handy. It generates arithmetic progressions::"
msgstr ""
msgid ""
">>> for i in range(5):\n"
"... print(i)\n"
"...\n"
"0\n"
"1\n"
"2\n"
"3\n"
"4"
msgstr ""
msgid ""
"The given end point is never part of the generated sequence; ``range(10)`` "
"generates 10 values, the legal indices for items of a sequence of length "
"10. It is possible to let the range start at another number, or to specify "
"a different increment (even negative; sometimes this is called the 'step')::"
msgstr ""
msgid ""
">>> list(range(5, 10))\n"
"[5, 6, 7, 8, 9]\n"
"\n"
">>> list(range(0, 10, 3))\n"
"[0, 3, 6, 9]\n"
"\n"
">>> list(range(-10, -100, -30))\n"
"[-10, -40, -70]"
msgstr ""
msgid ""
"To iterate over the indices of a sequence, you can combine :func:`range` "
"and :func:`len` as follows::"
msgstr ""
msgid ""
">>> a = ['Mary', 'had', 'a', 'little', 'lamb']\n"
">>> for i in range(len(a)):\n"
"... print(i, a[i])\n"
"...\n"
"0 Mary\n"
"1 had\n"
"2 a\n"
"3 little\n"
"4 lamb"
msgstr ""
msgid ""
"In most such cases, however, it is convenient to use the :func:`enumerate` "
"function, see :ref:`tut-loopidioms`."
msgstr ""
msgid "A strange thing happens if you just print a range::"
msgstr ""
msgid ""
">>> range(10)\n"
"range(0, 10)"
msgstr ""
msgid ""
"In many ways the object returned by :func:`range` behaves as if it is a "
"list, but in fact it isn't. It is an object which returns the successive "
"items of the desired sequence when you iterate over it, but it doesn't "
"really make the list, thus saving space."
msgstr ""
msgid ""
"We say such an object is :term:`iterable`, that is, suitable as a target for "
"functions and constructs that expect something from which they can obtain "
"successive items until the supply is exhausted. We have seen that the :"
"keyword:`for` statement is such a construct, while an example of a function "
"that takes an iterable is :func:`sum`::"
msgstr ""
msgid ""
">>> sum(range(4)) # 0 + 1 + 2 + 3\n"
"6"
msgstr ""
msgid ""
"Later we will see more functions that return iterables and take iterables as "
"arguments. In chapter :ref:`tut-structures`, we will discuss :func:`list` "
"in more detail."
msgstr ""
msgid ":keyword:`!break` and :keyword:`!continue` Statements"
msgstr ""
msgid ""
"The :keyword:`break` statement breaks out of the innermost enclosing :"
"keyword:`for` or :keyword:`while` loop::"
msgstr ""
msgid ""
">>> for n in range(2, 10):\n"
"... for x in range(2, n):\n"
"... if n % x == 0:\n"
"... print(f\"{n} equals {x} * {n//x}\")\n"
"... break\n"
"...\n"
"4 equals 2 * 2\n"
"6 equals 2 * 3\n"
"8 equals 2 * 4\n"
"9 equals 3 * 3"
msgstr ""
msgid ""
"The :keyword:`continue` statement continues with the next iteration of the "
"loop::"
msgstr ""
msgid ""
">>> for num in range(2, 10):\n"
"... if num % 2 == 0:\n"
"... print(f\"Found an even number {num}\")\n"
"... continue\n"
"... print(f\"Found an odd number {num}\")\n"
"...\n"
"Found an even number 2\n"
"Found an odd number 3\n"
"Found an even number 4\n"
"Found an odd number 5\n"
"Found an even number 6\n"
"Found an odd number 7\n"
"Found an even number 8\n"
"Found an odd number 9"
msgstr ""
msgid ":keyword:`!else` Clauses on Loops"
msgstr ""
msgid ""
"In a :keyword:`!for` or :keyword:`!while` loop the :keyword:`!break` "
"statement may be paired with an :keyword:`!else` clause. If the loop "
"finishes without executing the :keyword:`!break`, the :keyword:`!else` "
"clause executes."
msgstr ""
msgid ""
"In a :keyword:`for` loop, the :keyword:`!else` clause is executed after the "
"loop finishes its final iteration, that is, if no break occurred."
msgstr ""
msgid ""
"In a :keyword:`while` loop, it's executed after the loop's condition becomes "
"false."
msgstr ""
msgid ""
"In either kind of loop, the :keyword:`!else` clause is **not** executed if "
"the loop was terminated by a :keyword:`break`. Of course, other ways of "
"ending the loop early, such as a :keyword:`return` or a raised exception, "
"will also skip execution of the :keyword:`else` clause."
msgstr ""
msgid ""
"This is exemplified in the following :keyword:`!for` loop, which searches "
"for prime numbers::"
msgstr ""
msgid ""
">>> for n in range(2, 10):\n"
"... for x in range(2, n):\n"
"... if n % x == 0:\n"
"... print(n, 'equals', x, '*', n//x)\n"
"... break\n"
"... else:\n"
"... # loop fell through without finding a factor\n"
"... print(n, 'is a prime number')\n"
"...\n"
"2 is a prime number\n"
"3 is a prime number\n"
"4 equals 2 * 2\n"
"5 is a prime number\n"
"6 equals 2 * 3\n"
"7 is a prime number\n"
"8 equals 2 * 4\n"
"9 equals 3 * 3"
msgstr ""
msgid ""
"(Yes, this is the correct code. Look closely: the ``else`` clause belongs "
"to the ``for`` loop, **not** the ``if`` statement.)"
msgstr ""
msgid ""
"One way to think of the else clause is to imagine it paired with the ``if`` "
"inside the loop. As the loop executes, it will run a sequence like if/if/if/"
"else. The ``if`` is inside the loop, encountered a number of times. If the "
"condition is ever true, a ``break`` will happen. If the condition is never "
"true, the ``else`` clause outside the loop will execute."
msgstr ""
msgid ""
"When used with a loop, the ``else`` clause has more in common with the "
"``else`` clause of a :keyword:`try` statement than it does with that of "
"``if`` statements: a ``try`` statement's ``else`` clause runs when no "
"exception occurs, and a loop's ``else`` clause runs when no ``break`` "
"occurs. For more on the ``try`` statement and exceptions, see :ref:`tut-"
"handling`."
msgstr ""
msgid ":keyword:`!pass` Statements"
msgstr ""
msgid ""
"The :keyword:`pass` statement does nothing. It can be used when a statement "
"is required syntactically but the program requires no action. For example::"
msgstr ""
msgid ""
">>> while True:\n"
"... pass # Busy-wait for keyboard interrupt (Ctrl+C)\n"
"..."
msgstr ""
msgid "This is commonly used for creating minimal classes::"
msgstr ""
msgid ""
">>> class MyEmptyClass:\n"
"... pass\n"
"..."
msgstr ""
msgid ""
"Another place :keyword:`pass` can be used is as a place-holder for a "
"function or conditional body when you are working on new code, allowing you "
"to keep thinking at a more abstract level. The :keyword:`!pass` is silently "
"ignored::"
msgstr ""
msgid ""
">>> def initlog(*args):\n"
"... pass # Remember to implement this!\n"
"..."
msgstr ""
msgid ""
"For this last case, many people use the ellipsis literal :code:`...` instead "
"of :code:`pass`. This use has no special meaning to Python, and is not part "
"of the language definition (you could use any constant expression here), "
"but :code:`...` is used conventionally as a placeholder body as well. See :"
"ref:`bltin-ellipsis-object`."
msgstr ""
msgid ":keyword:`!match` Statements"
msgstr ""
msgid ""
"A :keyword:`match` statement takes an expression and compares its value to "
"successive patterns given as one or more case blocks. This is superficially "
"similar to a switch statement in C, Java or JavaScript (and many other "
"languages), but it's more similar to pattern matching in languages like Rust "
"or Haskell. Only the first pattern that matches gets executed and it can "
"also extract components (sequence elements or object attributes) from the "
"value into variables. If no case matches, none of the branches is executed."
msgstr ""
msgid ""
"The simplest form compares a subject value against one or more literals::"
msgstr ""
msgid ""
"def http_error(status):\n"
" match status:\n"
" case 400:\n"
" return \"Bad request\"\n"
" case 404:\n"
" return \"Not found\"\n"
" case 418:\n"
" return \"I'm a teapot\"\n"
" case _:\n"
" return \"Something's wrong with the internet\""
msgstr ""
msgid ""
"Note the last block: the \"variable name\" ``_`` acts as a *wildcard* and "
"never fails to match."
msgstr ""
msgid ""
"You can combine several literals in a single pattern using ``|`` (\"or\")::"
msgstr ""
msgid ""
"case 401 | 403 | 404:\n"
" return \"Not allowed\""
msgstr ""
msgid ""
"Patterns can look like unpacking assignments, and can be used to bind "
"variables::"
msgstr ""
msgid ""
"# point is an (x, y) tuple\n"
"match point:\n"
" case (0, 0):\n"
" print(\"Origin\")\n"
" case (0, y):\n"
" print(f\"Y={y}\")\n"
" case (x, 0):\n"
" print(f\"X={x}\")\n"
" case (x, y):\n"
" print(f\"X={x}, Y={y}\")\n"
" case _:\n"
" raise ValueError(\"Not a point\")"
msgstr ""
msgid ""
"Study that one carefully! The first pattern has two literals, and can be "
"thought of as an extension of the literal pattern shown above. But the next "
"two patterns combine a literal and a variable, and the variable *binds* a "
"value from the subject (``point``). The fourth pattern captures two values, "
"which makes it conceptually similar to the unpacking assignment ``(x, y) = "
"point``."
msgstr ""
msgid ""
"If you are using classes to structure your data you can use the class name "
"followed by an argument list resembling a constructor, but with the ability "
"to capture attributes into variables::"
msgstr ""
msgid ""
"class Point:\n"
" def __init__(self, x, y):\n"
" self.x = x\n"
" self.y = y\n"
"\n"
"def where_is(point):\n"
" match point:\n"
" case Point(x=0, y=0):\n"
" print(\"Origin\")\n"
" case Point(x=0, y=y):\n"
" print(f\"Y={y}\")\n"
" case Point(x=x, y=0):\n"
" print(f\"X={x}\")\n"
" case Point():\n"
" print(\"Somewhere else\")\n"
" case _:\n"
" print(\"Not a point\")"
msgstr ""
msgid ""
"You can use positional parameters with some builtin classes that provide an "
"ordering for their attributes (e.g. dataclasses). You can also define a "
"specific position for attributes in patterns by setting the "
"``__match_args__`` special attribute in your classes. If it's set to (\"x\", "
"\"y\"), the following patterns are all equivalent (and all bind the ``y`` "
"attribute to the ``var`` variable)::"
msgstr ""
msgid ""
"Point(1, var)\n"
"Point(1, y=var)\n"
"Point(x=1, y=var)\n"
"Point(y=var, x=1)"
msgstr ""
msgid ""
"A recommended way to read patterns is to look at them as an extended form of "
"what you would put on the left of an assignment, to understand which "
"variables would be set to what. Only the standalone names (like ``var`` "
"above) are assigned to by a match statement. Dotted names (like ``foo."
"bar``), attribute names (the ``x=`` and ``y=`` above) or class names "
"(recognized by the \"(...)\" next to them like ``Point`` above) are never "
"assigned to."
msgstr ""
msgid ""
"Patterns can be arbitrarily nested. For example, if we have a short list of "
"Points, with ``__match_args__`` added, we could match it like this::"
msgstr ""
msgid ""
"class Point:\n"
" __match_args__ = ('x', 'y')\n"
" def __init__(self, x, y):\n"
" self.x = x\n"
" self.y = y\n"
"\n"
"match points:\n"
" case []:\n"
" print(\"No points\")\n"
" case [Point(0, 0)]:\n"
" print(\"The origin\")\n"
" case [Point(x, y)]:\n"
" print(f\"Single point {x}, {y}\")\n"
" case [Point(0, y1), Point(0, y2)]:\n"
" print(f\"Two on the Y axis at {y1}, {y2}\")\n"
" case _:\n"
" print(\"Something else\")"
msgstr ""
msgid ""
"We can add an ``if`` clause to a pattern, known as a \"guard\". If the "
"guard is false, ``match`` goes on to try the next case block. Note that "
"value capture happens before the guard is evaluated::"
msgstr ""
msgid ""
"match point:\n"
" case Point(x, y) if x == y:\n"
" print(f\"Y=X at {x}\")\n"
" case Point(x, y):\n"
" print(f\"Not on the diagonal\")"
msgstr ""
msgid "Several other key features of this statement:"
msgstr ""
msgid ""
"Like unpacking assignments, tuple and list patterns have exactly the same "
"meaning and actually match arbitrary sequences. An important exception is "
"that they don't match iterators or strings."
msgstr ""
msgid ""
"Sequence patterns support extended unpacking: ``[x, y, *rest]`` and ``(x, y, "
"*rest)`` work similar to unpacking assignments. The name after ``*`` may "
"also be ``_``, so ``(x, y, *_)`` matches a sequence of at least two items "
"without binding the remaining items."
msgstr ""
msgid ""
"Mapping patterns: ``{\"bandwidth\": b, \"latency\": l}`` captures the "
"``\"bandwidth\"`` and ``\"latency\"`` values from a dictionary. Unlike "
"sequence patterns, extra keys are ignored. An unpacking like ``**rest`` is "
"also supported. (But ``**_`` would be redundant, so it is not allowed.)"
msgstr ""
msgid "Subpatterns may be captured using the ``as`` keyword::"
msgstr ""
msgid "case (Point(x1, y1), Point(x2, y2) as p2): ..."
msgstr ""
msgid ""
"will capture the second element of the input as ``p2`` (as long as the input "
"is a sequence of two points)"
msgstr ""
msgid ""
"Most literals are compared by equality, however the singletons ``True``, "
"``False`` and ``None`` are compared by identity."
msgstr ""
msgid ""
"Patterns may use named constants. These must be dotted names to prevent "
"them from being interpreted as capture variables::"
msgstr ""
msgid ""
"from enum import Enum\n"
"class Color(Enum):\n"
" RED = 'red'\n"
" GREEN = 'green'\n"
" BLUE = 'blue'\n"
"\n"
"color = Color(input(\"Enter your choice of 'red', 'blue' or 'green': \"))\n"
"\n"
"match color:\n"
" case Color.RED:\n"
" print(\"I see red!\")\n"
" case Color.GREEN:\n"
" print(\"Grass is green\")\n"
" case Color.BLUE:\n"
" print(\"I'm feeling the blues :(\")"
msgstr ""
msgid ""
"For a more detailed explanation and additional examples, you can look into :"
"pep:`636` which is written in a tutorial format."
msgstr ""
msgid "Defining Functions"
msgstr ""
msgid ""
"We can create a function that writes the Fibonacci series to an arbitrary "
"boundary::"
msgstr ""
msgid ""
">>> def fib(n): # write Fibonacci series less than n\n"
"... \"\"\"Print a Fibonacci series less than n.\"\"\"\n"
"... a, b = 0, 1\n"
"... while a < n:\n"
"... print(a, end=' ')\n"
"... a, b = b, a+b\n"
"... print()\n"
"...\n"
">>> # Now call the function we just defined:\n"
">>> fib(2000)\n"
"0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597"
msgstr ""
msgid ""
"The keyword :keyword:`def` introduces a function *definition*. It must be "
"followed by the function name and the parenthesized list of formal "
"parameters. The statements that form the body of the function start at the "
"next line, and must be indented."
msgstr ""
msgid ""
"The first statement of the function body can optionally be a string literal; "
"this string literal is the function's documentation string, or :dfn:"
"`docstring`. (More about docstrings can be found in the section :ref:`tut-"
"docstrings`.) There are tools which use docstrings to automatically produce "
"online or printed documentation, or to let the user interactively browse "
"through code; it's good practice to include docstrings in code that you "
"write, so make a habit of it."
msgstr ""
msgid ""
"The *execution* of a function introduces a new symbol table used for the "
"local variables of the function. More precisely, all variable assignments "
"in a function store the value in the local symbol table; whereas variable "
"references first look in the local symbol table, then in the local symbol "
"tables of enclosing functions, then in the global symbol table, and finally "
"in the table of built-in names. Thus, global variables and variables of "
"enclosing functions cannot be directly assigned a value within a function "
"(unless, for global variables, named in a :keyword:`global` statement, or, "
"for variables of enclosing functions, named in a :keyword:`nonlocal` "
"statement), although they may be referenced."
msgstr ""
msgid ""
"The actual parameters (arguments) to a function call are introduced in the "
"local symbol table of the called function when it is called; thus, arguments "
"are passed using *call by value* (where the *value* is always an object "
"*reference*, not the value of the object). [#]_ When a function calls "
"another function, or calls itself recursively, a new local symbol table is "
"created for that call."
msgstr ""
msgid ""
"A function definition associates the function name with the function object "
"in the current symbol table. The interpreter recognizes the object pointed "
"to by that name as a user-defined function. Other names can also point to "
"that same function object and can also be used to access the function::"
msgstr ""
msgid ""
">>> fib\n"
"<function fib at 10042ed0>\n"
">>> f = fib\n"
">>> f(100)\n"
"0 1 1 2 3 5 8 13 21 34 55 89"
msgstr ""
msgid ""
"Coming from other languages, you might object that ``fib`` is not a function "
"but a procedure since it doesn't return a value. In fact, even functions "
"without a :keyword:`return` statement do return a value, albeit a rather "
"boring one. This value is called ``None`` (it's a built-in name). Writing "
"the value ``None`` is normally suppressed by the interpreter if it would be "
"the only value written. You can see it if you really want to using :func:"
"`print`::"
msgstr ""
msgid ""
">>> fib(0)\n"
">>> print(fib(0))\n"
"None"
msgstr ""
msgid ""
"It is simple to write a function that returns a list of the numbers of the "
"Fibonacci series, instead of printing it::"
msgstr ""
msgid ""
">>> def fib2(n): # return Fibonacci series up to n\n"
"... \"\"\"Return a list containing the Fibonacci series up to n.\"\"\"\n"
"... result = []\n"
"... a, b = 0, 1\n"
"... while a < n:\n"
"... result.append(a) # see below\n"
"... a, b = b, a+b\n"
"... return result\n"
"...\n"
">>> f100 = fib2(100) # call it\n"
">>> f100 # write the result\n"
"[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]"
msgstr ""
msgid "This example, as usual, demonstrates some new Python features:"
msgstr ""
msgid ""
"The :keyword:`return` statement returns with a value from a function. :"
"keyword:`!return` without an expression argument returns ``None``. Falling "
"off the end of a function also returns ``None``."
msgstr ""
msgid ""
"The statement ``result.append(a)`` calls a *method* of the list object "
"``result``. A method is a function that 'belongs' to an object and is named "
"``obj.methodname``, where ``obj`` is some object (this may be an "
"expression), and ``methodname`` is the name of a method that is defined by "
"the object's type. Different types define different methods. Methods of "
"different types may have the same name without causing ambiguity. (It is "
"possible to define your own object types and methods, using *classes*, see :"
"ref:`tut-classes`) The method :meth:`~list.append` shown in the example is "
"defined for list objects; it adds a new element at the end of the list. In "
"this example it is equivalent to ``result = result + [a]``, but more "
"efficient."
msgstr ""
msgid "More on Defining Functions"
msgstr ""
msgid ""
"It is also possible to define functions with a variable number of arguments. "
"There are three forms, which can be combined."
msgstr ""
msgid "Default Argument Values"
msgstr ""
msgid ""
"The most useful form is to specify a default value for one or more "
"arguments. This creates a function that can be called with fewer arguments "
"than it is defined to allow. For example::"
msgstr ""
msgid ""
"def ask_ok(prompt, retries=4, reminder='Please try again!'):\n"
" while True:\n"
" reply = input(prompt)\n"
" if reply in {'y', 'ye', 'yes'}:\n"
" return True\n"
" if reply in {'n', 'no', 'nop', 'nope'}:\n"
" return False\n"
" retries = retries - 1\n"
" if retries < 0:\n"
" raise ValueError('invalid user response')\n"
" print(reminder)"
msgstr ""
msgid "This function can be called in several ways:"
msgstr ""
msgid ""
"giving only the mandatory argument: ``ask_ok('Do you really want to quit?')``"
msgstr ""
msgid ""
"giving one of the optional arguments: ``ask_ok('OK to overwrite the file?', "
"2)``"
msgstr ""
msgid ""
"or even giving all arguments: ``ask_ok('OK to overwrite the file?', 2, 'Come "
"on, only yes or no!')``"
msgstr ""
msgid ""
"This example also introduces the :keyword:`in` keyword. This tests whether "
"or not a sequence contains a certain value."
msgstr ""
msgid ""
"The default values are evaluated at the point of function definition in the "
"*defining* scope, so that ::"
msgstr ""
msgid ""
"i = 5\n"
"\n"
"def f(arg=i):\n"
" print(arg)\n"
"\n"
"i = 6\n"
"f()"
msgstr ""
msgid "will print ``5``."
msgstr ""
msgid ""
"**Important warning:** The default value is evaluated only once. This makes "
"a difference when the default is a mutable object such as a list, "
"dictionary, or instances of most classes. For example, the following "
"function accumulates the arguments passed to it on subsequent calls::"
msgstr ""
msgid ""
"def f(a, L=[]):\n"
" L.append(a)\n"
" return L\n"
"\n"
"print(f(1))\n"
"print(f(2))\n"
"print(f(3))"
msgstr ""
msgid "This will print ::"
msgstr ""
msgid ""
"[1]\n"
"[1, 2]\n"
"[1, 2, 3]"
msgstr ""
msgid ""
"If you don't want the default to be shared between subsequent calls, you can "
"write the function like this instead::"
msgstr ""
msgid ""
"def f(a, L=None):\n"
" if L is None:\n"
" L = []\n"
" L.append(a)\n"
" return L"
msgstr ""
msgid "Keyword Arguments"
msgstr ""
msgid ""
"Functions can also be called using :term:`keyword arguments <keyword "
"argument>` of the form ``kwarg=value``. For instance, the following "
"function::"
msgstr ""
msgid ""
"def parrot(voltage, state='a stiff', action='voom', type='Norwegian Blue'):\n"
" print(\"-- This parrot wouldn't\", action, end=' ')\n"
" print(\"if you put\", voltage, \"volts through it.\")\n"
" print(\"-- Lovely plumage, the\", type)\n"
" print(\"-- It's\", state, \"!\")"
msgstr ""
msgid ""
"accepts one required argument (``voltage``) and three optional arguments "
"(``state``, ``action``, and ``type``). This function can be called in any "
"of the following ways::"
msgstr ""
msgid ""
"parrot(1000) # 1 positional "
"argument\n"
"parrot(voltage=1000) # 1 keyword argument\n"
"parrot(voltage=1000000, action='VOOOOOM') # 2 keyword arguments\n"
"parrot(action='VOOOOOM', voltage=1000000) # 2 keyword arguments\n"
"parrot('a million', 'bereft of life', 'jump') # 3 positional "
"arguments\n"
"parrot('a thousand', state='pushing up the daisies') # 1 positional, 1 "
"keyword"
msgstr ""
msgid "but all the following calls would be invalid::"
msgstr ""
msgid ""
"parrot() # required argument missing\n"
"parrot(voltage=5.0, 'dead') # non-keyword argument after a keyword "
"argument\n"
"parrot(110, voltage=220) # duplicate value for the same argument\n"
"parrot(actor='John Cleese') # unknown keyword argument"
msgstr ""
msgid ""
"In a function call, keyword arguments must follow positional arguments. All "
"the keyword arguments passed must match one of the arguments accepted by the "
"function (e.g. ``actor`` is not a valid argument for the ``parrot`` "
"function), and their order is not important. This also includes non-"
"optional arguments (e.g. ``parrot(voltage=1000)`` is valid too). No argument "
"may receive a value more than once. Here's an example that fails due to this "
"restriction::"
msgstr ""
msgid ""
">>> def function(a):\n"
"... pass\n"
"...\n"
">>> function(0, a=0)\n"
"Traceback (most recent call last):\n"
" File \"<stdin>\", line 1, in <module>\n"
"TypeError: function() got multiple values for argument 'a'"
msgstr ""
msgid ""
"When a final formal parameter of the form ``**name`` is present, it receives "
"a dictionary (see :ref:`typesmapping`) containing all keyword arguments "
"except for those corresponding to a formal parameter. This may be combined "
"with a formal parameter of the form ``*name`` (described in the next "
"subsection) which receives a :ref:`tuple <tut-tuples>` containing the "
"positional arguments beyond the formal parameter list. (``*name`` must "
"occur before ``**name``.) For example, if we define a function like this::"
msgstr ""
msgid ""
"def cheeseshop(kind, *arguments, **keywords):\n"
" print(\"-- Do you have any\", kind, \"?\")\n"
" print(\"-- I'm sorry, we're all out of\", kind)\n"
" for arg in arguments:\n"
" print(arg)\n"
" print(\"-\" * 40)\n"
" for kw in keywords:\n"
" print(kw, \":\", keywords[kw])"
msgstr ""
msgid "It could be called like this::"
msgstr ""
msgid ""
"cheeseshop(\"Limburger\", \"It's very runny, sir.\",\n"
" \"It's really very, VERY runny, sir.\",\n"
" shopkeeper=\"Michael Palin\",\n"
" client=\"John Cleese\",\n"
" sketch=\"Cheese Shop Sketch\")"
msgstr ""
msgid "and of course it would print:"
msgstr ""
msgid ""
"-- Do you have any Limburger ?\n"
"-- I'm sorry, we're all out of Limburger\n"
"It's very runny, sir.\n"
"It's really very, VERY runny, sir.\n"
"----------------------------------------\n"
"shopkeeper : Michael Palin\n"
"client : John Cleese\n"
"sketch : Cheese Shop Sketch"
msgstr ""
msgid ""
"Note that the order in which the keyword arguments are printed is guaranteed "
"to match the order in which they were provided in the function call."
msgstr ""
msgid "Special parameters"
msgstr ""
msgid ""
"By default, arguments may be passed to a Python function either by position "
"or explicitly by keyword. For readability and performance, it makes sense to "
"restrict the way arguments can be passed so that a developer need only look "
"at the function definition to determine if items are passed by position, by "
"position or keyword, or by keyword."
msgstr ""
msgid "A function definition may look like:"
msgstr ""
msgid ""
"def f(pos1, pos2, /, pos_or_kwd, *, kwd1, kwd2):\n"
" ----------- ---------- ----------\n"
" | | |\n"
" | Positional or keyword |\n"
" | - Keyword only\n"
" -- Positional only"
msgstr ""
msgid ""
"where ``/`` and ``*`` are optional. If used, these symbols indicate the kind "
"of parameter by how the arguments may be passed to the function: positional-"
"only, positional-or-keyword, and keyword-only. Keyword parameters are also "
"referred to as named parameters."
msgstr ""
msgid "Positional-or-Keyword Arguments"
msgstr ""
msgid ""
"If ``/`` and ``*`` are not present in the function definition, arguments may "
"be passed to a function by position or by keyword."
msgstr ""