码厩开发者笔记

#101 Python 国密（sm3）

sm3 是我国设计的一种哈希算法，根据维基百科信息，大致相当于 sha256。

#100 Python 内置函数: hash

一个不值一提的小问题：
有个地方使用 hash 方法来做哈希计算，将字符串转换成一个数值，但是发现改用 Python 3 之后，这个值每次运行都不一样了。

#99 哈希：数字摘要

开发时，有时候我们需要将任意字符串映射成一个数字或字符串，这就是哈希。

#98 给头像加上五星红旗

效果：

#97 Python 源码学习 11: PyFrameObject

// Include/cpython/frameobject.h
struct _frame {
    PyObject_VAR_HEAD
    struct _frame *f_back;      /* previous frame, or NULL */
    PyCodeObject *f_code;       /* code segment */
    PyObject *f_builtins;       /* builtin symbol table (PyDictObject) */
    PyObject *f_globals;        /* global symbol table (PyDictObject) */
    PyObject *f_locals;         /* local symbol table (any mapping) */
    PyObject **f_valuestack;    /* points after the last local */
    /* Next free slot in f_valuestack.  Frame creation sets to f_valuestack.
       Frame evaluation usually NULLs it, but a frame that yields sets it
       to the current stack top. */
    PyObject **f_stacktop;
    PyObject *f_trace;          /* Trace function */
    char f_trace_lines;         /* Emit per-line trace events? */
    char f_trace_opcodes;       /* Emit per-opcode trace events? */

    /* Borrowed reference to a generator, or NULL */
    PyObject *f_gen;

    int f_lasti;                /* Last instruction if called */
    /* Call PyFrame_GetLineNumber() instead of reading this field
       directly.  As of 2.3 f_lineno is only valid when tracing is
       active (i.e. when f_trace is set).  At other times we use
       PyCode_Addr2Line to calculate the line from the current
       bytecode index. */
    int f_lineno;               /* Current line number */
    int f_iblock;               /* index in f_blockstack */
    char f_executing;           /* whether the frame is still executing */
    PyTryBlock f_blockstack[CO_MAXBLOCKS]; /* for try and loop blocks */
    PyObject *f_localsplus[1];  /* locals+stack, dynamically sized */
};

// Include/pyframe.h
typedef struct _frame PyFrameObject;

字节码

def sum(a, b):
    return a + b

def test():
    print('hello world')
    print(sum(1, 2))

import dis
dis.dis(sum)
dis.dis(test)

2           0 LOAD_FAST                0 (a)
            2 LOAD_FAST                1 (b)
            4 BINARY_ADD
            6 RETURN_VALUE
5           0 LOAD_GLOBAL              0 (print)
            2 LOAD_CONST               1 ('hello world')
            4 CALL_FUNCTION            1
            6 POP_TOP

6           8 LOAD_GLOBAL              0 (print)
           10 LOAD_GLOBAL              1 (sum)
           12 LOAD_CONST               2 (1)
           14 LOAD_CONST               3 (2)
           16 CALL_FUNCTION            2
           18 CALL_FUNCTION            1
           20 POP_TOP
           22 LOAD_CONST               0 (None)
           24 RETURN_VALUE

行号，指令偏移，指令，参数，参数值（参考）

查看字节码：

sum.__code__.co_code
sum.__code__.co_varnames
sum.__code__.co_consts
sum.__code__.co_names

参考资料与拓展阅读

• 实验楼, Python 异步网络编程实战 > 函数执行过程

#96 Python 源码学习 09: set

我都有点怀疑我这个学习计划是否是正确的。

同样的废话，就懒得说了，只说有价值的信息。

1. 疑问：代码中的 clinic 相关文件不知道是做什么用的。
2. set 和 frozenset 的定义在一起。不是这次看代码，我简直忘了还有 frozenset 这个类型的存在。

汇总了一下，所有的类型：

1. PyAsyncGen_Type
2. PyBaseObject_Type
3. PyBlake2_BLAKE2bType
4. PyBlake2_BLAKE2sType
5. PyBool_Type
6. PyBufferedIOBase_Type
7. PyBufferedRandom_Type
8. PyBufferedReader_Type
9. PyBufferedRWPair_Type
10. PyBufferedWriter_Type
11. PyByteArrayIter_Type
12. PyByteArray_Type
13. PyBytesIO_Type
14. PyBytesIter_Type
15. PyBytes_Type
16. PyCallIter_Type
17. PyCapsule_Type
18. PyCArg_Type
19. PyCArray_Type
20. PyCArrayType_Type
21. PyCData_Type
22. PyCell_Type
23. PyCField_Type
24. PyCFuncPtr_Type
25. PyCFuncPtrType_Type
26. PyCFunction_Type
27. PyClassMethodDescr_Type
28. PyClassMethod_Type
29. PyCMethod_Type
30. PyCode_Type
31. PyComplex_Type
32. PyContextTokenMissing_Type
33. PyContextToken_Type
34. PyContext_Type
35. PyContextVar_Type
36. PyCoro_Type
37. PyCPointer_Type
38. PyCPointerType_Type
39. PyCSimpleType_Type
40. PyCStgDict_Type
41. PyCStructType_Type
42. PyCThunk_Type
43. PyCursesWindow_Type
44. PyCursesWindow_Type;
45. PyDictItems_Type
46. PyDictIterItem_Type
47. PyDictIterKey_Type
48. PyDictIterValue_Type
49. PyDictKeys_Type
50. PyDictProxy_Type
51. PyDictRevIterItem_Type
52. PyDictRevIterKey_Type
53. PyDictRevIterValue_Type
54. PyDict_Type
55. PyDictValues_Type
56. PyEllipsis_Type
57. PyEnum_Type
58. PyFileIO_Type
59. PyFileIO_Type;
60. PyFilter_Type
61. PyFloat_Type
62. PyFrame_Type
63. PyFrozenSet_Type
64. PyFunction_Type
65. Py_GenericAliasType
66. PyGen_Type
67. PyGetSetDescr_Type
68. PyHKEY_Type
69. PyIncrementalNewlineDecoder_Type
70. PyInstanceMethod_Type
71. PyIOBase_Type
72. PyListIter_Type
73. PyListRevIter_Type
74. PyList_Type
75. PyLongRangeIter_Type
76. PyLong_Type
77. PyMap_Type
78. PyMemberDescr_Type
79. PyMemoryView_Type
80. PyMethodDescr_Type
81. PyMethod_Type
82. PyModuleDef_Type
83. PyModule_Type
84. PyODictItems_Type
85. PyODictIter_Type
86. PyODictKeys_Type
87. PyODict_Type
88. PyODictValues_Type
89. PyPickleBuffer_Type
90. PyProperty_Type
91. PyRangeIter_Type
92. PyRange_Type
93. PyRawIOBase_Type
94. PyReversed_Type
95. PySeqIter_Type
96. PySetIter_Type
97. PySet_Type
98. PySlice_Type
99. PyStaticMethod_Type
100. PyStdPrinter_Type
101. PySTEntry_Type
102. PyStringIO_Type
103. PyST_Type
104. PySuper_Type
105. PyTextIOBase_Type
106. PyTextIOWrapper_Type
107. PyTraceBack_Type
108. PyTupleIter_Type
109. PyTuple_Type
110. PyType_Type
111. PyUnicodeIter_Type
112. PyUnicode_Type
113. PyWindowsConsoleIO_Type
114. PyWindowsConsoleIO_Type;
115. PyWrapperDescr_Type
116. PyZip_Type

#95 数学推导 + 纯Python实现机器学习算法

微信公众号上看到公众号机器学习实验室的系列文章 Python 机器学习算法实现, 感觉非常好，就学习学习吧！

#94 Python 源码学习 08: dict

类型定义

INIT_TYPE(&PyDict_Type, "dict");
SETBUILTIN("dict", &PyDict_Type);

PyTypeObject PyDict_Type 的定义在 Objects/dictobject.c 中。

Include/cpython/dictobject.h

typedef struct {
    PyObject_HEAD

    /* Number of items in the dictionary */
    Py_ssize_t ma_used;

    /* Dictionary version: globally unique, value change each time
       the dictionary is modified */
    uint64_t ma_version_tag;

    PyDictKeysObject *ma_keys;

    /* If ma_values is NULL, the table is "combined": keys and values
       are stored in ma_keys.

       If ma_values is not NULL, the table is splitted:
       keys are stored in ma_keys and values are stored in ma_values */
    PyObject **ma_values;
} PyDictObject;

成员方法

setdefault

#define DICT_SETDEFAULT_METHODDEF    \
    {"setdefault", (PyCFunction)(void(*)(void))dict_setdefault, METH_FASTCALL, dict_setdefault__doc__},

static PyObject *
dict_setdefault(PyDictObject *self, PyObject *const *args, Py_ssize_t nargs)
{
    PyObject *return_value = NULL;
    PyObject *key;
    PyObject *default_value = Py_None;

    if (!_PyArg_CheckPositional("setdefault", nargs, 1, 2)) {
        goto exit;
    }
    key = args[0];
    if (nargs < 2) {
        goto skip_optional;
    }
    default_value = args[1];
skip_optional:
    return_value = dict_setdefault_impl(self, key, default_value);

exit:
    return return_value;
}

static PyObject *
dict_setdefault_impl(PyDictObject *self, PyObject *key,
                     PyObject *default_value)
/*[clinic end generated code: output=f8c1101ebf69e220 input=0f063756e815fd9d]*/
{
    PyObject *val;

    val = PyDict_SetDefault((PyObject *)self, key, default_value);
    Py_XINCREF(val);
    return val;
}

#93 Python 源码学习 07: list

cpython/Include/cpython/tupleobject.h

INIT_TYPE(&PyList_Type, "list");
SETBUILTIN("list", &PyList_Type);

PyTypeObject PyList_Type 的定义在 Objects/listobject.c 中。

成员方法

相关的方法在 #define LIST_.+_METHODDEF 的定义中，比如 extend 方法：

#define LIST_APPEND_METHODDEF    \
    {"append", (PyCFunction)list_append, METH_O, list_append__doc__},

static PyObject *
list_append(PyListObject *self, PyObject *object)
/*[clinic end generated code: output=7c096003a29c0eae input=43a3fe48a7066e91]*/
{
    if (app1(self, object) == 0)
        Py_RETURN_NONE;
    return NULL;
}

static int
app1(PyListObject *self, PyObject *v)
{
    Py_ssize_t n = PyList_GET_SIZE(self);

    assert (v != NULL);
    if (n == PY_SSIZE_T_MAX) {
        PyErr_SetString(PyExc_OverflowError,
            "cannot add more objects to list");
        return -1;
    }

    if (list_resize(self, n+1) < 0)
        return -1;

    Py_INCREF(v);
    PyList_SET_ITEM(self, n, v);
    return 0;
}

#92 Python 源码学习 06: tuple

源码

INIT_TYPE(&PyTuple_Type, "tuple");
SETBUILTIN("tuple", &PyTuple_Type);

**cpython/Include/cpython/tupleobject.h**

typedef struct {
    PyObject_VAR_HEAD
    /* ob_item contains space for 'ob_size' elements.
       Items must normally not be NULL, except during construction when
       the tuple is not yet visible outside the function that builds it. */
    PyObject *ob_item[1];
} PyTupleObject;

当然，与之对应的 PyTypeObject PyTuple_Type 定义在 Objects/tupleobject.c，就不贴出来了。

PyTuple_SET_ITEM 似乎是在完成内存初始化的空间内填充元素时使用的。

成员方法

tuple 类型只有两个成员方法：count, index

#define TUPLE_INDEX_METHODDEF    \
    {"index", (PyCFunction)(void(*)(void))tuple_index, METH_FASTCALL, tuple_index__doc__},

#define TUPLE_COUNT_METHODDEF    \
    {"count", (PyCFunction)tuple_count, METH_O, tuple_count__doc__},

static PyMethodDef tuple_methods[] = {
    TUPLE___GETNEWARGS___METHODDEF
    TUPLE_INDEX_METHODDEF
    TUPLE_COUNT_METHODDEF
    {"__class_getitem__", (PyCFunction)Py_GenericAlias, METH_O|METH_CLASS, PyDoc_STR("See PEP 585")},
    {NULL,              NULL}           /* sentinel */
};

引用计数

Py_INCREF
Py_DECREF
Py_XINCREF
Py_XDECREF