【发布时间】：2011-01-20 04:10:53
【问题描述】：
我想做一些类似于我相信变更控制系统所做的事情，它们比较两个文件，并在每次文件更改时保存一个小的差异。 我一直在阅读此页面：http://docs.python.org/library/difflib.html，显然它并没有陷入我的脑海。
我试图在下面显示的一个简单的程序中重新创建它， 但我似乎缺少的是 Delta 包含的内容至少与原始文件一样多，甚至更多。
难道不能只做纯粹的改变吗？
我问的原因很明显 - 节省磁盘空间。
我可以每次只保存整个代码块，但最好保存一次当前代码，然后保存更改的小差异。
我还在试图弄清楚为什么许多 difflib 函数返回一个生成器而不是一个列表，那里有什么优势？
difflib 对我有用吗？还是我需要找到一个更专业、功能更多的软件包？
# Python Difflib demo
# Author: Neal Walters
# loosely based on http://ahlawat.net/wordpress/?p=371
# 01/17/2011
# build the files here - later we will just read the files probably
file1Contents="""
for j = 1 to 10:
print "ABC"
print "DEF"
print "HIJ"
print "JKL"
print "Hello World"
print "j=" + j
print "XYZ"
"""
file2Contents = """
for j = 1 to 10:
print "ABC"
print "DEF"
print "HIJ"
print "JKL"
print "Hello World"
print "XYZ"
print "The end"
"""
filename1 = "diff_file1.txt"
filename2 = "diff_file2.txt"
file1 = open(filename1,"w")
file2 = open(filename2,"w")
file1.write(file1Contents)
file2.write(file2Contents)
file1.close()
file2.close()
#end of file build
lines1 = open(filename1, "r").readlines()
lines2 = open(filename2, "r").readlines()
import difflib
print "\n FILE 1 \n"
for line in lines1:
print line
print "\n FILE 2 \n"
for line in lines2:
print line
diffSequence = difflib.ndiff(lines1, lines2)
print "\n ----- SHOW DIFF ----- \n"
for i, line in enumerate(diffSequence):
print line
diffObj = difflib.Differ()
deltaSequence = diffObj.compare(lines1, lines2)
deltaList = list(deltaSequence)
print "\n ----- SHOW DELTALIST ----- \n"
for i, line in enumerate(deltaList):
print line
#let's suppose we store just the diffSequence in the database
#then we want to take the current file (file2) and recreate the original (file1) from it
#by backward applying the diff
restoredFile1Lines = difflib.restore(diffSequence,1) # 1 indicates file1 of 2 used to create the diff
restoreFileList = list(restoredFile1Lines)
print "\n ----- SHOW REBUILD OF FILE1 ----- \n"
# this is not showing anything!
for i, line in enumerate(restoreFileList):
print line
谢谢！
更新：
contextDiffSeq = difflib.context_diff(lines1, lines2)
contextDiffList = list(contextDiffSeq)
print "\n ----- SHOW CONTEXTDIFF ----- \n"
for i, line in enumerate(contextDiffList):
print line
----- 显示上下文 -----
* 5,9 **
print "HIJ" print "JKL" print "Hello World"
打印 "j=" + j
打印“XYZ”
--- 5,9 ----
print "HIJ" print "JKL" print "Hello World" print "XYZ"
- 打印“结束”
另一个更新：
在 Panvalet an Librarian 的旧时代，大型机的源代码管理工具，您可以创建这样的变更集：
++ADD 9
print "j=" + j
这只是意味着在第 9 行之后添加一行（或多行）。 然后是 ++REPLACE 或 ++UPDATE 之类的单词。 http://www4.hawaii.gov/dags/icsd/ppmo/Stds_Web_Pages/pdf/it110401.pdf
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