Python 2.7 在文本文件中的字符之间写入？

我有一个我想写进去的模块。我有几个问题。其中之一是在文件中查找字符串。目前，我打开文件，然后在文件名中使用for行，然后执行if以确定是否找到字符串，所有这些都有效。然而，在它被注释掉之前，现在我试图确定它在使用tell时的位置。然而这给了我一个不正确的位置，我相信是1118，而不是660。因此，我手动确定了使用seek的位置

然而，第二个问题是，如果我在文件中的位置写入此文件，它只会覆盖其中的所有数据。我想插入数据，而不是覆盖它

除非我在希望写入的位置插入一个字符长度相等的字符串，否则它将覆盖大多数if语句和下面类似的内容

有没有办法天真地做到这一点

这是我要写入的文件

# Filename: neo_usercurves.py
# Created By: Gregory Smith
# Description: A script containing a library of user created curves
# Purpose: A library to store names of all the user curves, and deletes curves
#   if specified to do so

import os
import maya.cmds as mc
import module_locator

my_path = module_locator.module_path()

def usercurve_lib(fbxfile=None, remove=None):
    """All control/curve objects created by user

    Keyword Arguments:
    fbxfile -- (string) name of fbx file to import
    remove -- (boolean) will remove an entry from the library and delete the
        associated fbx file
    """
    curves_dict = {
    #crvstart

    #crvend
    }
    if remove is None:
        return curves_dict
    elif not remove:
        try:
            name = mc.file(curves_dict[fbxfile], typ='FBX', i=1,
                iv=True, pmt=False)
            return name[0]
        except RuntimeError:
            return None
    else:
        try:
            os.remove('%s\%s.fbx' %(my_path, fbxfile))
            return '%s.fbx' %(fbxfile)
        except OSError:
            print 'File %s does not exist.' %(fbxfile)
            return None

这是下面的代码，我正在一个名为neo_curves.py的模块中运行。这不是完整的代码，“my_path”只是运行neo_curves.py的当前目录的路径

def create_entry(self, crv):    

    """Exports user curve to user data directory and adds entry into
        neo_usercurves.py

        Keyword Arguments:
        crv -- (PyNode) the object to export
        """
        # set settings
        mel.eval('FBXExportFileVersion "FBX201400"')
        mel.eval('FBXExportInputConnections -v 0')
        select(crv)
        mc.file('%s\userdat\%s.fbx' %(my_path, str(crv)), force=True, options='',
            typ='FBX export', pr=True, es=True)
        with open('%s\userdat\\neo_usercurves.py' %(my_path), 'r+') as usercrvs:
            for line in usercrvs:
                if line.strip() == '#crvstart':
                    #linepos = usercrvs.tell()
                    #linepos = int(linepos)
                    #usercrvs.seek(linepos, 0)
                    usercrvs.seek(665, 0)
                    usercrvs.write("\n    "+str(crv)+" : '%s\%s' %(my_path, '"+
                       str(crv)+".fbx')")
                    break

这将给我以下结果：

# Filename: neo_usercurves.py
# Created By: Gregory Smith
# Description: A script containing a library of user created curves
# Purpose: A library to store names of all the user curves, and deletes curves
#   if specified to do so

import os
import maya.cmds as mc
import module_locator

my_path = module_locator.module_path()

def usercurve_lib(fbxfile=None, remove=None):
    """All control/curve objects created by user

    Keyword Arguments:
    fbxfile -- (string) name of fbx file to import
    remove -- (boolean) will remove an entry from the library and delete the
        associated fbx file
    """
    curves_dict = {
    #crvstart
    loop_crv : '%s\%s' %(my_path, 'loop_crv.fbx')     return curves_dict
    elif not remove:
        try:
            name = mc.file(curves_dict[fbxfile], typ='FBX', i=1,
                iv=True, pmt=False)
            return name[0]
        except RuntimeError:
            return None
    else:
        try:
            os.remove('%s\%s.fbx' %(my_path, fbxfile))
            return '%s.fbx' %(fbxfile)
        except OSError:
            print 'File %s does not exist.' %(fbxfile)
            return None

---

简言之：在大多数操作系统上，如果长度不相同，则在不重写的情况下无法插入到文件中

请查看此处的详细讨论：

可能重复：