[Patches] [ python-Patches-914575 ] difflib side by side diff support, diff.py s/b/s HTML option

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Patches item #914575, was opened at 2004-03-11 15:50
Message generated for change (Comment added) made by asouzis
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Category: Modules
Group: Python 2.4
Status: Open
Resolution: None
Priority: 6
Submitted By: Dan Gass (dmgass)
Assigned to: Nobody/Anonymous (nobody)
Summary: difflib side by side diff support, diff.py s/b/s HTML option

Initial Comment:
lib/difflib.py:

Added support for generating side by side differences.  
Intended to be used for generating HTML pages but is 
generic where it can be used for other types of markup.

tools/scripts/diff.py:

Added -m option to use above patch to generate an 
HTML page of side by side differences between two 
files.  The existing -c option when used with the new -m 
option controls whether contextual differences are 
shown or whether the entire file is displayed (number of 
context lines is controlled by existing -l option).

NOTES:
(1) Textual context diffs were included as requested.  In 
addition, full and contextual HTML side by side 
differences (that this patch generated) are also included 
to assist in analyzing the differences and showing an 
example.

(2) If this functionality is worthy of inclusion in the 
standard python distribution, I am willing to provide more 
documentation or make modifications to change the 
interface or make improvements.

(3) When using Internet Explorer some font sizes seem 
to skew things a bit.  Generally I've found the "smallest" 
to work best.  If someone knows why, I'd be interested 
in making any necessary adjustments in the generated 
HTML.


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Comment By: Adam Souzis (asouzis)
Date: 2004-07-23 13:01

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certainly you need to be able to access the templates and
modify them. And should be documented too -- one of the
first things i wanted to know is how can i customize the
output. But a config object seems like conceptual clutter.
keyword arguments can be ignored and are just as persistent
if you use ** on a dict. 

few more suggestions:
* the default font seems too large on both ie 6 and firefox
(this is with 1200 x 800 screen resolution, so it'd be even
larger at a lower resolution).
* maybe the links column (t, f, n) should also be on the
left -- often there are long lines and you need to scroll
over to access it.
* add class attributes to the two tables used in the
templates and move their styles to there (except i believe
that IE doesn't honor cellpadding/spacing styles in css)

thanks

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Comment By: Jim Jewett (jimjjewett)
Date: 2004-07-23 09:31

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Actually, I'm not convinced that the templates should be 
private, though I can certainly see protected.  (double-
underscore private is mangled; single-underscore protected will 
be left out of some imports and doco, but acts like a regular 
variable if people choose to use it anyway.)

I'm still thinking about nnorwitz's suggestion; the config option 
could be ignored by most people ("use the defaults") but would 
hold persistent state for people with explicit preferences (since 
they'll probably want to make the same changes to all 
compares).


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Comment By: Neal Norwitz (nnorwitz)
Date: 2004-07-23 09:10

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I have not reviewed the code yet, so this is just a general
comment.  I don't know if it is applicable.

You could create a configuration class that has attributes.
 A user would only need to assign to the params that they
want to update.  If you change the names you could add
properties to deal with backwards compatibility.

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Comment By: Dan Gass (dmgass)
Date: 2004-07-23 08:48

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I agree the API for make_file() and make_table() has alot of
optional parameters that can look daunting.  The alternative
of providing accessor methods is less appealing to me.  It
sounds like Jim & I are in agreement on this.

As far as the compromise of making the templates private
members, I am assuming Jim is in favor of it.  I'm in favor
of them being members, it doesn't matter to me if they are
private.  I'll wait until Raymond weighs in on this one
before I move on it.

Jim -- Thanks for your input.


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Comment By: Jim Jewett (jimjjewett)
Date: 2004-07-23 08:17

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For a context or unified diff, you don't really need to 
parametrize it very much.  Having a much larger API for side-
by-side puts things out of balance, which can make side-by-
side look either more difficult or preferred.

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Comment By: Dan Gass (dmgass)
Date: 2004-07-23 06:57

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Maybe a good compromise would be to leave them members of
the class but name them to imply they are private (add a
leading underscore).  That way if someone wants to create
their own subclass they can at their own risk.  They can
always write a little extra logic to insure the interface
didn't change and raise a custom exception explaining what
happened and what they need to look at.

I didn't read (2) in Raymond's comments.  Could you expand
on those concerns?


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Comment By: Jim Jewett (jimjjewett)
Date: 2004-07-23 06:24

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I agree that users should be able to override the template.

I think Raymond was concerned about 

(1) backwards compatibility if you want to change the 
interface.  For instance, you might later decide that there 
should be separate templates for header/footer/match section/
changed line/added line/deleted line.

(2) matching the other diff options, so this doesn't look far 
more complicated.

Unfortunately, at the moment I don't see a good way to solve 
those; using a private member and access functions wouldn't 
really simplify things much.



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Comment By: Dan Gass (dmgass)
Date: 2004-07-23 04:53

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I intend on implementing all the suggestions from the last
two comment submissions when I hear back from Raymond
Hettinger.  I'm questioning making the templates private
global variables.  I intentionally made them members of a
class so that they could be overridden when the class is
subclassed.

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Comment By: Raymond Hettinger (rhettinger)
Date: 2004-07-19 06:12

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Unfortunately, I do not have time to give this more review.

Several thoughts:
- consider making mdiff as private.  that will leave its API
flexible to accomodate future changes
- move the templates to private global variables and work to
improve their indentation so that the html is readable
- inline the code for _escape from sax.  the three replaces
are not worth the interdependency
- the methods work fine with properly formatted input but
crash badly when the newlines have been stripped.  So,
either make the code more flexible or add error handling.
- overall, nice job.


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Comment By: Adam Souzis (asouzis)
Date: 2004-07-17 12:12

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The diffs look cool but if the to and from lines are
identical an exception is thrown:

  File "<string>", line 23, in makeDiff
  File "c:\_dev\rx4rdf\rx\htmldiff.py", line 1687, in make_file
    summary=summary))
  File "c:\_dev\rx4rdf\rx\htmldiff.py", line 1741, in make_table
    if not diff_flags[0]:
IndexError: list index out of range

(This is on python 2.3.3 -- I renamed your difflib.py to
htmldiff.py and put it in site-packages)

Perhaps you should add the case of two identical files to
test_difflib.py.

thanks

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Comment By: Dan Gass (dmgass)
Date: 2004-07-16 02:16

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Since I have not gotten any feedback on the user interface I 
took the liberty to tweek it the best I thought how.  Since I 
consider this new functionality very solid I went ahead and 
created changes to the documentation and test suite.

Per Martin v. Löwis (loewis) instructions I generated a patch 
which hopefully meets his needs.  My CVS access is limited to 
the web interface and thus the patch is based on the latest 
checked in as of today:

python/python/dist/src/Lib/difflib.py -- rev 1.21
python/python/dist/src/Tools/scripts/diff.py -- rev 1.2
python/python/dist/src/Lib/test/test_difflib.py -- rev 1.10
python/python/dist/src/Doc/lib/libdifflib.tex -- rev 1.17

Note, I am not very familiar with .tex but it seemed straight 
forward.  I editted the file by hand and it should be very close 
to what I intended.  Unfortunately I am not set up to convert 
the .tex to HTML.  I may try that next week.

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Comment By: Dan Gass (dmgass)
Date: 2004-07-16 02:13

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Since I have not gotten any feedback on the user interface I 
took the liberty to tweek it the best I thought how.  Since I 
consider this new functionality very solid I went ahead and 
created changes to the documentation and test suite.

Per Martin v. Löwis (loewis) instructions I generated a patch 
which hopefully meets his needs.  My CVS access is limited to 
the web interface and thus the patch is based on the latest 
checked in as of today:

python/python/dist/src/Lib/difflib.py -- rev 1.21
python/python/dist/src/Tools/scripts/diff.py -- rev 1.2
python/python/dist/src/Lib/test/test_difflib.py -- rev 1.10
python/python/dist/src/Doc/lib/libdifflib.tex -- rev 1.17

Note, I am not very familiar with .tex but it seemed straight 
forward.  I editted the file by hand and it should be very close 
to what I intended.  Unfortunately I am not set up to convert 
the .tex to HTML.  I may try that next week.

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Comment By: Martin v. Löwis (loewis)
Date: 2004-07-14 23:30

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The pack lacks changes to the documentation (libdifflib.tex)
and changes to the test suite. Please always submit patches
as single unified or context diffs, rather than zip files of
the revised files.

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Comment By: Dan Gass (dmgass)
Date: 2004-07-02 11:17

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With the updated patch code I just posted, both full and
contextual differences pass the validator.w3.org check
(XHTML 1.0 Transitional).  Also the extra carriage returns
put in by DOS were removed from the difflib.py patch.

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Comment By: Walter Dörwald (doerwalter)
Date: 2004-06-25 11:01

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Submitting difflib_context.html to validator.w3.org gives 2333 
errors. The character encoding is missing and there's no 
DOCTYPE declaration. The rest of the errors seem to be 
mostly related to the nowrap attribute (which must be written 
as nowrap="nowrap", as this is the only allowed value). 
Furthermore the patch contains a mix of CR and CRLF 
terminated lines.

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Comment By: Dan Gass (dmgass)
Date: 2004-06-23 23:23

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I just attached an updated patch.  I based the patch on 
diff.py(CVS1.1) and difflib.py(CVS1.20) which was the latest I 
saw today on viewCVS.

The following enhancements were made:
1) user interface greatly simplified for generating HTML (see 
diff.py for example)
2) generated HTML now 4.01 Transitional compliant (so says 
HTML Tidy)
3) HTML color scheme for differences now matches that used 
by viewCVS.
4) differences table now has a row for each line making the 
HTML less susceptible to browser quirks.
5) took care of all issues to date enumerated here in this 
patch.

It would be great if I could get some help on:
A) getting some JavaScript? written to be able to select and 
cut text from a single column (right now text is selected from 
the whole row including both "from" and "to" text and line 
numbers.
B) solving the line width issue.  Currently the "from" / "to" 
column is as wide as the widest line.  Any ideas on wrapping 
or scrolling?

As of now the only feature I may want to add in the near 
future is optional tab expansion.

Thanks to those that have commented here and emailed me 
with suggestions and advice!

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Comment By: Jim Jewett (jimjjewett)
Date: 2004-06-11 07:35

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Thank you; I have often wished for side-by-side, but not quite 
badly enough to write it.

That said, I would recommend some tweaks to the formatting.

"font" is deprecated; "span" would be better. 

On my display, the "next" lines don't always seem to be 
counted (except the first one), so that the anchors column is 
not lined up with the others.  (This would also be fixed by the 
separate rows suggestion.)

Ideally, the line numbers would be in a separate column from 
the code, to make cut'n'paste easier.  (Then you could replace 
font.num (or span.num) with td.linenum.)

Ideally, each change group should be a separate row in the 
table.  (I realize that this probably means a two-layer iterator, 
so that the line breaks and blank lines can be inserted 
correctly in the code columns.)


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Comment By: Dan Gass (dmgass)
Date: 2004-04-28 21:30

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Also, I will need to submit the fix for making it behave nice 
when there are no differences!!

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Comment By: Dan Gass (dmgass)
Date: 2004-04-09 06:30

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In the time since submission I've found that the interface to 
the chgFmt and lineFmt functions (arguments of mdiff) should 
include both the line number and an indication of side 
(from/to).  The use for it I've found is for dropping anchors 
into the generated markup that it can be hyperlinked from 
elsewhere.

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