如何使用traceit在堆栈跟踪中报告函数输入变量 [英] How to use traceit to report function input variables in stack trace

问题描述

我一直在使用以下代码跟踪程序的执行情况：

I've been using the following code to trace the execution of my programs:

import sys
import linecache
import random

def traceit(frame, event, arg):
    if event == "line":
        lineno = frame.f_lineno
        filename = frame.f_globals["__file__"]
        if filename == "<stdin>":
            filename = "traceit.py"
        if (filename.endswith(".pyc") or
            filename.endswith(".pyo")):
            filename = filename[:-1]
        name = frame.f_globals["__name__"]
        line = linecache.getline(filename, lineno)
        print "%s:%s:%s: %s" % (name,  lineno,frame.f_code.co_name , line.rstrip())
    return traceit


def main():
    print "In main"
    for i in range(5):
        print i, random.randrange(0, 10)
    print "Done."

sys.settrace(traceit)
main()

使用这些代码或类似的代码可以报告某些函数参数的值吗？换句话说，上面的代码告诉我哪些函数被调用，我想知道这些函数调用的输入变量的相应值的什么。

Using this code, or something like it, is it possible to report the values of certain function arguments? In other words, the above code tells me "which" functions were called and I would like to know "what" the corresponding values of the input variables for those function calls.

提前感谢

推荐答案

frame.f_locals会给你本地变量的值，我想你可以跟踪你看到的最后一帧，如果frame.f_back不是最后一帧转储frame.f_locals。

frame.f_locals will give you the values of the local variables, and I guess you could keep track of the last frame you've seen and if frame.f_back is not the lastframe dump frame.f_locals.

我会预测，你很快就会下载了太多的数据这样做。

I'd predict though that you're pretty quickly going be snowed under with too much data doing this.

这是你的代码修改为这样做：

Here's your code modified to do this:

import sys
import linecache
import random

class Tracer(object):
    def __init__(self):
        self.lastframe = None

    def traceit(self, frame, event, arg):
        if event == "line":
            lineno = frame.f_lineno
            filename = frame.f_globals["__file__"]
            if filename == "<stdin>":
                filename = "traceit.py"
            if (filename.endswith(".pyc") or
                filename.endswith(".pyo")):
                filename = filename[:-1]
            name = frame.f_globals["__name__"]
            line = linecache.getline(filename, lineno)
            if frame.f_back is self.lastframe:
                print "%s:%s:%s: %s" % (name,  lineno,frame.f_code.co_name , line.rstrip())
            else:
                print "%s:%s:%s(%s)" % (name,  lineno,frame.f_code.co_name , str.join(', ', ("%s=%r" % item for item in frame.f_locals.iteritems())))

                print "%s:%s:%s: %s" % (name,  lineno,frame.f_code.co_name , line.rstrip())
                #print frame.f_locals
            self.lastframe = frame.f_back
        return self.traceit


def main():
    print "In main"
    for i in range(5):
        print i, random.randrange(0, 10)
    print "Done."

sys.settrace(Tracer().traceit)
main()

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