V tej vadnici bomo spoznali Pythonove dokumente. Natančneje, s pomočjo primerov bomo izvedeli, kako in zakaj se docstrings uporabljajo.
Doktrni nizi Python so nizovne dobesedne črke, ki se pojavijo takoj po definiciji funkcije, metode, razreda ali modula. Vzemimo primer.
Primer 1: Doktrinzi
def square(n): '''Takes in a number n, returns the square of n''' return n**2
Tukaj je niz literal:
'' 'Vnese število n, vrne kvadrat n' ''
Znotraj trojnimi narekovaji je docstring funkcije square(), kot se zdi prav po definiciji.
Opomba: Za ustvarjanje dokumentov lahko uporabimo tudi trojne """navednice.
Python Comments vs Docstrings
Komentarji Pythona
Komentarji so opisi, ki programerjem pomagajo, da bolje razumejo namen in funkcionalnost programa. Tolmač Python jih popolnoma prezre.
V Pythonu #za pisanje enovrstičnega komentarja uporabljamo simbol hash . Na primer
# Program to print "Hello World" print("Hello World")
Python komentira z uporabo nizov
Če nobeni spremenljivki ne dodelimo nizov, delujejo kot komentarji. Na primer
"I am a single-line comment" ''' I am a multi-line comment! ''' print("Hello World")
Opomba: Za večvrstične nize uporabljamo trojne narekovaje.
Python docstrings
Kot smo že omenili, so docstrini Pythona nizi, ki se uporabljajo takoj po definiciji funkcije, metode, razreda ali modula (kot v primeru 1 ). Uporabljajo se za dokumentiranje naše kode.
Do teh dokumentov lahko dostopamo z uporabo __doc__atributa.
Atribut Python __doc__
Kadar so nizni literali prisotni tik po definiciji funkcije, modula, razreda ali metode, so povezani z objektom kot njihovim __doc__atributom. Kasneje lahko s tem atributom pridobimo ta dokument.
Primer 2: Tiskanje dokumentov
def square(n): '''Takes in a number n, returns the square of n''' return n**2 print(square.__doc__)
Izhod
Vzame število n, vrne kvadrat n
Tukaj square()lahko z __doc__atributom dostopate do dokumentacije naše funkcije .
Zdaj pa poglejmo docstrings za vgrajeno funkcijo print():
Primer 3: Doktrini za vgrajeno funkcijo print ()
print(print.__doc__)
Izhod
print (value,…, sep = '', end = ' n', file = sys.stdout, flush = False) Natisne vrednosti v tok ali privzeto v sys.stdout. Izbirni argumenti ključnih besed: datoteka: datoteki podoben objekt (tok); privzeto je trenutni sys.stdout. sep: niz, vstavljen med vrednostmi, privzeto presledek. konec: niz, dodan za zadnjo vrednostjo, privzeto nova vrstica. splakovanje: ali prisilno splakovati potok.
Tu lahko vidimo, da je dokumentacija print()funkcije prisotna kot __doc__atribut te funkcije.
Enovrstični docstrings v Pythonu
Enovrstni dokumenti so dokumenti, ki ustrezajo eni vrstici.
Standardne konvencije za pisanje enovrstičnih dokumentov:
- Čeprav so enojni, še vedno uporabljamo trojne narekovaje okoli teh dokumentov, saj jih je mogoče kasneje enostavno razširiti.
- Zaključne ponudbe so v isti vrstici kot začetne ponudbe.
- Pred ali po dokumentu ni prazne vrstice.
- Ne smejo biti opisni, temveč morajo slediti strukturi »Naredi to, vrni tisto«, ki se konča s piko.
Vzemimo primer.
Primer 4: Napišite funkcijo enovrstičnih dokumentov
def multiplier(a, b): """Takes in two numbers, returns their product.""" return a*b
Večvrstični dokumentarni nizi v Pythonu
Večvrstični dokumentarni nizi so sestavljeni iz vrstice s povzetkom, tako kot enovrstična vrstica dokumentov, sledi prazna vrstica, ki ji sledi natančnejši opis.
Dokument PEP 257 vsebuje standardne konvencije za pisanje večvrstičnih dokumentov za različne predmete.
Nekateri so navedeni spodaj:
1. Docstrings za Python module
- Docstrings za module Python naj vsebujejo vse razpoložljive razrede, funkcije, predmete in izjeme, ki se uvozijo ob uvozu modula.
- They should also have a one-line summary for each item.
They are written at the beginning of the Python file.
Let's look at the docstrings for the builtin module in Python called pickle.
Example 4: Docstrings of Python module
import pickle print(pickle.__doc__)
Output
Create portable serialized representations of Python objects. See module copyreg for a mechanism for registering custom picklers. See module pickletools source for extensive comments. Classes: Pickler Unpickler Functions: dump(object, file) dumps(object) -> string load(file) -> object loads(string) -> object Misc variables: __version__ format_version compatible_formats
Here, we can see that the docstring written at the beginning of the pickle.py module file can be accessed as its docstring.
2. Docstrings for Python Functions
- The docstring for a function or method should summarize its behavior and document its arguments and return values.
- It should also list all the exceptions that can be raised and other optional arguments.
Example 5: Docstrings for Python functions
def add_binary(a, b): ''' Returns the sum of two decimal numbers in binary digits. Parameters: a (int): A decimal integer b (int): Another decimal integer Returns: binary_sum (str): Binary string of the sum of a and b ''' binary_sum = bin(a+b)(2:) return binary_sum print(add_binary.__doc__)
Output
Returns the sum of two decimal numbers in binary digits. Parameters: a (int): A decimal integer b (int): Another decimal integer Returns: binary_sum (str): Binary string of the sum of a and b
As you can see, we have included a short description of what the function does, the parameter it takes in and the value it returns. The string literal is embedded to the function add_binary as its __doc__ attribute.
3. Docstrings for Python Classes
- The docstrings for classes should summarize its behavior and list the public methods and instance variables.
- The subclasses, constructors, and methods should each have their own docstrings.
Example 6: Docstrings for Python class
Suppose we have a Person.py file with the following code:
class Person: """ A class to represent a person.… Attributes ---------- name : str first name of the person surname : str family name of the person age : int age of the person Methods ------- info(additional=""): Prints the person's name and age. """ def __init__(self, name, surname, age): """ Constructs all the necessary attributes for the person object. Parameters ---------- name : str first name of the person surname : str family name of the person age : int age of the person """ self.name = name self.surname = surname self.age = age def info(self, additional=""): """ Prints the person's name and age. If the argument 'additional' is passed, then it is appended after the main info. Parameters ---------- additional : str, optional More info to be displayed (default is None) Returns ------- None """ print(f'My name is (self.name) (self.surname). I am (self.age) years old.' + additional)
Here, we can use the following code to access only the docstrings of the Person class:
print(Person.__doc__)
Output
A class to represent a person.… Attributes ---------- name : str first name of the person surname : str family name of the person age : int age of the person Methods ------- info(additional=""): Prints the person's name and age
Using the help() Function for Docstrings
We can also use the help() function to read the docstrings associated with various objects.
Example 7: Read Docstrings with the help() function
We can use the help() function on the class Person in Example 6 as:
help(Person)
Output
Help on class Person in module __main__: class Person(builtins.object) | Person(name, surname, age) | | A class to represent a person. | |… | | Attributes | ---------- | name : str | first name of the person | surname : str | family name of the person | age : int | age of the person | | Methods | ------- | info(additional=""): | Prints the person's name and age. | | Methods defined here: | | __init__(self, name, surname, age) | Constructs all the necessary attributes for the person object. | | Parameters | ---------- | name : str | first name of the person | surname : str | family name of the person | age : int | age of the person | | info(self, additional='') | Prints the person's name and age. | | If the argument 'additional' is passed, then it is appended after the main info. | | Parameters | ---------- | additional : str, optional | More info to be displayed (default is None) | | Returns | ------- | None | | ---------------------------------------------------------------------- | Data descriptors defined here: | | __dict__ | dictionary for instance variables (if defined) | | __weakref__ | list of weak references to the object (if defined)
Here, we can see that the help() function retrieves the docstrings of the Person class along with the methods associated with that class.
4. Docstrings for Python Scripts
- The docstrings for Python script should document the script's functions and command-line syntax as a usable message.
- It should serve as a quick reference to all the functions and arguments.
5. Docstrings for Python Packages
The docstrings for a Python package is written in the package's __init__.py file.
- It should contain all the available modules and sub-packages exported by the package.
Docstring Formats
We can write docstring in many formats like the reStructured text (reST) format, Google format or the NumPy documentation format. To learn more, visit Popular Docstring Formats
Dokumentacijo lahko ustvarimo tudi iz dokumentov z uporabo orodij, kot je Sphinx. Če želite izvedeti več, obiščite Uradno dokumentacijo o sfingi
