Python

Python是一種面向對象、解釋型的程序設計語言。

這是一個識記性的頁面，詳細內容請參考此頁面的子頁面

1 Lexical analysis

files must be analysed into tokens.

1.1 Line Structure

files are divided into logical lines.

1.2 Logical Lines

represented by the token NEWLINE.

1.3 Physical Lines

換行符

1.5 Encoding declarations

文件開頭的coding標識

1.6 Explicit line joining

\

1.7 Implicit line joining

(),{},[]

1.8 Indentation

is used to determine the grouping of statements.

2 Identifiers and keywords

2.1 Reserved classes of identifiers

__*__, __*

3 Literals

constant values of some built-in types.

3.1 String and Bytes literals

stringliteral   ::=  [stringprefix](shortstring | longstring)
stringprefix    ::=  "r" | "R"
shortstring     ::=  "'" shortstringitem* "'" | '"' shortstringitem* '"'
longstring      ::=  "'''" longstringitem* "'''" | '"""' longstringitem* '"""'
shortstringitem ::=  shortstringchar | stringescapeseq
longstringitem  ::=  longstringchar | stringescapeseq
shortstringchar ::=  <any source character except "\" or newline or the quote>
longstringchar  ::=  <any source character except "\">
stringescapeseq ::=  "\" <any source character>

bytesliteral   ::=  bytesprefix(shortbytes | longbytes)
bytesprefix    ::=  "b" | "B" | "br" | "Br" | "bR" | "BR"
shortbytes     ::=  "'" shortbytesitem* "'" | '"' shortbytesitem* '"'
longbytes      ::=  "'''" longbytesitem* "'''" | '"""' longbytesitem* '"""'
shortbytesitem ::=  shortbyteschar | bytesescapeseq
longbytesitem  ::=  longbyteschar | bytesescapeseq
shortbyteschar ::=  <any ASCII character except "\" or newline or the quote>
longbyteschar  ::=  <any ASCII character except "\">
bytesescapeseq ::=  "\" <any ASCII character>

3.2 Integer literals

integer        ::=  decimalinteger | octinteger | hexinteger | bininteger
decimalinteger ::=  nonzerodigit digit* | "0"+
nonzerodigit   ::=  "1"..."9"
digit          ::=  "0"..."9"
octinteger     ::=  "0" ("o" | "O") octdigit+
hexinteger     ::=  "0" ("x" | "X") hexdigit+
bininteger     ::=  "0" ("b" | "B") bindigit+
octdigit       ::=  "0"..."7"
hexdigit       ::=  digit | "a"..."f" | "A"..."F"
bindigit       ::=  "0" | "1"

3.3 Floating point literals

floatnumber   ::=  pointfloat | exponentfloat
pointfloat    ::=  [intpart] fraction | intpart "."
exponentfloat ::=  (intpart | pointfloat) exponent
intpart       ::=  digit+
fraction      ::=  "." digit+
exponent      ::=  ("e" | "E") ["+" | "-"] digit+

3.4 Imaginary literals

imagnumber ::=  (floatnumber | intpart) ("j" | "J")

4 Data model

4.1 Objects, values and types

objects一旦出生不能再改變，value是它的值，types決定了它支持的操作，types也是不能改變的。value可以改變的objects是mutable, 否則immutable。

reference是objects的名字，reference也可以指向其他objects.

containers是一種包含其他對象引用的對象，containers是否mutable與其內對象是否mutable是不同的，即使containers immutable, 但其內對象mutable，當期內對象改變了，containers也改變了。

4.2 The standard type hierarchy

4.2.3 numbers.Number

immutable, int, real, complex

4.2.4 Sequences

[],slice, len()

immutable: Strings, Tuples, Bytes

mutable: Lists, Bytes array.

4.2.5 Set types

immutable, no index, len

Set, Frozen Set

4.2.6 Mappings

mutable, dict[key] = value

4.2.7 Callable types

4.2.7.1 User-defined functions

__doc__, __name__, __default__, __code__, __global__,__dict__,__module__

4.2.7.2 Instance methods

__func__, __self__, __module__

4.2.7.3 Generator functions

__next__()

4.2.7.4 Built-in functions

__name__, __doc__, __module__

4.2.8 Modules

__global__, __dict__

4.3 Special method names

4.3.1 Basic customization

__new__, __init__, __del__, __repr__, __str__, __bytes__, __format__

__lt__, __le__, __eq__,__ne__,__gt__,__ge__

__hash__, __bool__

4.3.2 Customizing attribute access

__getattribute__, __getatt__, __setattr__, __delattr__, __dir__

4.3.3 Emulating callable objects

__len__, __getitem__, __setitem__, __delitem__, __iter__, __reversed__, __contains__,

5 Execution model

5.1 Naming and binding

name, binding, block, scope

7 Compound statements

compound_stmt ::=  if_stmt
                   | while_stmt
                   | for_stmt
                   | try_stmt
                   | with_stmt
                   | funcdef
                   | classdef
suite         ::=  stmt_list NEWLINE | NEWLINE INDENT statement+ DEDENT
statement     ::=  stmt_list NEWLINE | compound_stmt
stmt_list     ::=  simple_stmt (";" simple_stmt)* [";"]

7.1 The if statement

if_stmt ::=  "if" expression ":" suite
             ( "elif" expression ":" suite )*
             ["else" ":" suite]

7.2 The while statement

while_stmt ::=  "while" expression ":" suite
                ["else" ":" suite]

7.3 The for statement

for_stmt ::=  "for" target_list "in" expression_list ":" suite
              ["else" ":" suite]

7.4 The try statement

try_stmt  ::=  try1_stmt | try2_stmt
try1_stmt ::=  "try" ":" suite
               ("except" [expression ["as" target]] ":" suite)+
               ["else" ":" suite]
               ["finally" ":" suite]
try2_stmt ::=  "try" ":" suite
               "finally" ":" suite

7.5 The with statement

with_stmt ::=  "with" with_item ("," with_item)* ":" suite
with_item ::=  expression ["as" target]

7.6 Function definitions

funcdef        ::=  [decorators] "def" funcname "(" [parameter_list] ")" ["->" expression] ":" suite
decorators     ::=  decorator+
decorator      ::=  "@" dotted_name ["(" [parameter_list [","]] ")"] NEWLINE
dotted_name    ::=  identifier ("." identifier)*
parameter_list ::=  (defparameter ",")*
                    (  "*" [parameter] ("," defparameter)*
                    [, "**" parameter]
                    | "**" parameter
                    | defparameter [","] )
parameter      ::=  identifier [":" expression]
defparameter   ::=  parameter ["=" expression]
funcname       ::=  identifier

7.7 Class definitions

classdef    ::=  [decorators] "class" classname [inheritance] ":" suite
inheritance ::=  "(" [parameter_list] ")"
classname   ::=  identifier