在Python中，是否可以自动将传递给当前函数的变量的原始名称作为位置参数？
可以方便调试。例如，在一个漂亮的打印函数中，为每个转储值的输出添加前缀，而不是让调用者手动指定它。
获得类似内容的最明显方法可能是使用关键字参数，如：
# caution: Python3 code
def pprint_func(**kwargs):
for n, v in kwargs.items():
print("{}: {}".format(n, str(v)))
pprint_func(the_name="a value")
# this will output: "the_name: a value"
但这非常不方便，因为我们手动命名每个参数：）
我宁愿去寻找一些神奇的东西：
a_var = "Foo"
pprint_func(a_var, some_cat_func("Hello", "World"))
pprint_func函数会找到原始名称，然后在转储实际值之前将其打印出来：
a_var: 'Foo'
some_cat_func: 'Hello World'
如何在Python3.x中实现这一目标？
我假设我们需要访问调用上下文的源代码。 请请注意非常脏的选项，比如lexing /手动解析Python源代码绝对是不行的。
注意：此问题与previous one of mine有关。我创建了一个新问题，因为该主题已经发展。
另外，我发现this answer很有意思但如果传递的参数是调用的直接结果（即：pprint_func(result())）则不起作用，导致我的问题解决不完整。原始海报提供的 final solution尽可能地肮脏。
答案 0 :(得分：0)
看起来这样做的唯一方法是遍历调用者上下文的AST，搜索对当前函数的调用。然后，由于AST的结构，我们可以很容易地找到关于位置参数的所有信息。
我没有将此答案标记为接受，希望Python Guru能够通过并告诉真相
我已经做了一个实现，只是做了诀窍，并且通常情况下工作得很好。代码肯定值得进行一些改进，特别是find_caller_node部分，因为它尽可能精确，但不是100％。
此外，我必须read调用者的完整模块，因为inspect.getsource有时没有返回完整的源块（例如：调用者直接位于__main__; Python v3.4.2）。这是一个错误还是一个功能？
无论如何，请不要对代码过于苛刻，因为它应该仅用于调试和教育目的。
您可以找到latest version here。
这是后人的复制/粘贴版本：
#!/usr/bin/env python3
#
# pydump
# A Python3 pretty-printer that also does introspection to detect the original
# name of the passed variables
#
# Jean-Charles Lefebvre <polyvertex@gmail.com>
# Latest version at: http://gist.github.com/polyvertex (pydump)
#
# Usage:
# dbg_dump(
# my_var, None, True, 123, "Bar", (4, 5, 6), fcall(), hello="world")
# Result:
# my_var: 'Foo'
# None: None
# Bool: True
# Num: 123
# Str: 'Bar'
# Tuple: (4, 5, 6)
# fcall(): "Function's Result"
# hello: 'world'
#
import sys
import pprint
import inspect
import ast
def dbg_dump(
*args,
dumpopt_stream=sys.stderr,
dumpopt_forcename=True,
dumpopt_pformat={'indent': 2},
dumpopt_srcinfo=1,
**kwargs):
"""
Pretty-format every passed positional and named parameters, in that order,
prefixed by their **original** name (i.e.: the one used by the caller), or
by their type name for literals.
Depends on the *pprint*, *inspect* and *ast* modules, which are part of the
Python3 standard library.
Jean-Charles Lefebvre <polyvertex@gmail.com>
Latest version at: http://gist.github.com/polyvertex (pydump)
Note that the names of the keyword arguments you want to dump must not start
with "dumpopt_" since this prefix is used internally to differentiate
options over values to dump.
Also, the introspection code won't behave as expected if do recursive calls
to this function.
Options can be passed as keyword arguments to tweak behavior and output
format:
dumpopt_stream
May you wish to print() the result directly, you can pass a stream
object (e.g.: sys.stdout) through this option, that will be given
to print()'s "file" keyword argument.
You can also specify None in case you just want the output string
to be returned without further ado.
dumpopt_forcename
A boolean value to indicate wether you want every dumped value to
be prepended by its name (i.e.: its name or its type).
If False, only non-literal values will be named.
dumpopt_forcename
The dictionary of keyword arguments to give to pprint.pformat()
dumpopt_srcinfo
Specify a false value (None, False, zero) to skip caller's info.
Specify 1 to output caller's line number only.
Specify 2 to output caller's file name and line number.
Specify 3 or greater to output caller's file path and line number.
Example:
dbg_dump(
my_var, None, True, 123, "Bar", (4, 5, 6), fcall(), hello="world")
Result:
my_var: 'Foo'
None: None
Bool: True
Num: 123
Str: 'Bar'
Tuple: (4, 5, 6)
fcall(): "Function's Result"
hello: 'world'
"""
try:
def _find_caller_node(root_node, func_name, last_lineno):
# find caller's node by walking down the ast, searching for an
# ast.Call object named func_name of which the last source line is
# last_lineno
found_node = None
lineno = 0
def _luke_astwalker(parent):
nonlocal found_node
nonlocal lineno
for child in ast.iter_child_nodes(parent):
# break if we passed the last line
if hasattr(child, "lineno") and child.lineno:
lineno = child.lineno
if lineno > last_lineno:
break
# is it our candidate?
if (isinstance(child, ast.Name)
and isinstance(parent, ast.Call)
and child.id == func_name):
found_node = parent
break
_luke_astwalker(child)
_luke_astwalker(root_node)
return found_node
frame = inspect.currentframe()
backf = frame.f_back
this_func_name = frame.f_code.co_name
#this_func = backf.f_locals.get(
# this_func_name, backf.f_globals.get(this_func_name))
# get the source code of caller's module
# note that we have to reload the entire module file since the
# inspect.getsource() function doesn't work in some cases (i.e.:
# returned source content was incomplete... Why?!).
# --> is inspect.getsource broken???
# source = inspect.getsource(backf.f_code)
#source = inspect.getsource(backf.f_code)
with open(backf.f_code.co_filename, "r") as f:
source = f.read()
# get the ast node of caller's module
# we don't need to use ast.increment_lineno() since we've loaded the
# whole module
ast_root = ast.parse(source, backf.f_code.co_filename)
#ast.increment_lineno(ast_root, backf.f_code.co_firstlineno - 1)
# find caller's ast node
caller_node = _find_caller_node(ast_root, this_func_name, backf.f_lineno)
if not caller_node:
raise Exception("Caller's AST node not found")
# keep some useful info for later
src_info = {
'file': backf.f_code.co_filename,
'name': (
backf.f_code.co_filename.replace("\\", "/").rpartition("/")[2]),
'lineno': caller_node.lineno}
# if caller's node has been found, we now have the AST of our parameters
args_names = []
for arg_node in caller_node.args:
if isinstance(arg_node, ast.Name):
args_names.append(arg_node.id)
elif isinstance(arg_node, ast.Attribute):
if hasattr(arg_node, "value") and hasattr(arg_node.value, "id"):
args_names.append(arg_node.value.id + "." + arg_node.attr)
else:
args_names.append(arg_node.attr)
elif isinstance(arg_node, ast.Subscript):
args_names.append(arg_node.value.id + "[]")
elif (isinstance(arg_node, ast.Call)
and hasattr(arg_node, "func")
and hasattr(arg_node.func, "id")):
args_names.append(arg_node.func.id + "()")
elif dumpopt_forcename:
if (isinstance(arg_node, ast.NameConstant)
and arg_node.value is None):
args_names.append("None")
elif (isinstance(arg_node, ast.NameConstant)
and arg_node.value in (False, True)):
args_names.append("Bool")
else:
args_names.append(arg_node.__class__.__name__)
else:
args_names.append(None)
except:
src_info = None
args_names = [None] * len(args)
args_count = len(args) + len(kwargs)
output = ""
if dumpopt_srcinfo and src_info:
if dumpopt_srcinfo <= 1:
fmt = "D({2}):"
elif dumpopt_srcinfo == 2:
fmt = "{1}({2}):"
else:
fmt = "{0}({2}):"
output += fmt.format(
src_info['file'], src_info['name'], src_info['lineno'])
output += "\n" if args_count > 1 else " "
else:
src_info = None
for name, obj in zip(
args_names + list(kwargs.keys()),
list(args) + list(kwargs.values())):
if name and name.startswith("dumpopt_"):
continue
if src_info and args_count > 1:
output += " "
if name:
output += name + ": "
output += pprint.pformat(obj, **dumpopt_pformat) + "\n"
if dumpopt_stream:
print(output, end="", file=dumpopt_stream)
return None # explicit is better than implicit
else:
return output.rstrip()
if __name__ == "__main__":
def fcall():
return "Function's Result"
my_var = "Foo"
dbg_dump(
my_var, None, True, 123, "Bar", (4, 5, 6), fcall(),
dbg_dump(1, dumpopt_stream=None), hello="world")