f python?

hi guys,

sorry am feeling a bit prolifit lately.

today's show, is: 〈Fuck Python〉
http://xahlee.org/comp/fuck_python.html

------------------------------------
Fuck Python
By Xah Lee, 2012-04-08

fuck Python.

just fucking spend 2 hours and still going.

here's the short story.

so recently i switched to a Windows version of python. Now, Windows
version takes path using win backslash, instead of cygwin slash. This
fucking broke my find/replace scripts that takes a dir level as input.
Because i was counting slashes.

Ok no problem. My sloppiness. After all, my implementation wasn't
portable. So, let's fix it. After a while, discovered there's the
「os.sep�. Ok, replace 「"/"� to 「os.sep�, done. Then, bang, all hell
went lose. Because, the backslash is used as escape in string, so any
regex that manipulate path got fucked majorly. So, now you need to
find a quoting mechanism. Then, fuck python doc incomprehensible
scattered comp-sci-r-us BNF shit. Then, fuck python for “os.path� and
“os� modules then string object and string functions inconsistent
ball. And FUCK Guido who wants to fuck change python for his idiotic
OOP concept of “elegance� so that some of these are deprecated.

So after several exploration of “repr()�, “format()�, “‹str›.count()�,
“os.path.normpath()�, “re.split()�, “len(re.search().group())� etc,
after a long time, let's use “re.escape()�. 2 hours has passed. Also,
discovered that “os.path.walk� is now deprecated, and one is supposed
to use the sparkling “os.walk�. In the process of refreshing my
python, the “os.path.walk� semantics is really one fucked up fuck.
Meanwhile, the “os.walk� went into incomprehensible OOP object and
iterators fuck.

now, it's close to 3 hours. This fix is supposed to be done in 10 min.
I'd have done it in elisp in just 10 minutes if not for my
waywardness.

This is Before

def process_file(dummy, current_dir, file_list):
current_dir_level = len(re.split("/", current_dir)) -
len(re.split("/", input_dir))
cur_file_level = current_dir_level+1
if min_level <= cur_file_level <= max_level:
for a_file in file_list:
if re.search(r"\.html$", a_file, re.U) and
os.path.isfile(current_dir + "/" + a_file):
replace_string_in_file(current_dir + "/" + a_file)

This is After

def process_file(dummy, current_dir, file_list):
current_dir = os.path.normpath(current_dir)
cur_dir_level = re.sub( "^" + re.escape(input_dir), "",
current_dir).count( os.sep)
cur_file_level = cur_dir_level + 1
if min_level <= cur_file_level <= max_level:
for a_file in file_list:
if re.search(r"\.html$", a_file, re.U) and
os.path.isfile(current_dir + re.escape(os.sep) + a_file):
replace_string_in_file(current_dir + os.sep + a_file)
# print "%d %s" % (cur_file_level, (current_dir + os.sep +
a_file))

Complete File

# -*- coding: utf-8 -*-
# Python

# find & replace strings in a dir

import os, sys, shutil, re

# if this this is not empty, then only these files will be processed
my_files = []

input_dir = "c:/Users/h3/web/xahlee_org/lojban/hrefgram2/"
input_dir = "/cygdrive/c/Users/h3/web/zz"
input_dir = "c:/Users/h3/web/xahlee_org/"

min_level = 2; # files and dirs inside input_dir are level 1.
max_level = 2; # inclusive

print_no_change = False

find_replace_list = [

(
u"""<iframe style="width:100%;border:none" src="http://xahlee.org/
footer.html"></iframe>""",
u"""<iframe style="width:100%;border:none" src="../footer.html"></
iframe>""",
),

]

def replace_string_in_file(file_path):
"Replaces all findStr by repStr in file file_path"
temp_fname = file_path + "~lc~"
backup_fname = file_path + "~bk~"

# print "reading:", file_path
input_file = open(file_path, "rb")
file_content = unicode(input_file.read(), "utf-8")
input_file.close()

num_replaced = 0
for a_pair in find_replace_list:
num_replaced += file_content.count(a_pair[0])
output_text = file_content.replace(a_pair[0], a_pair[1])
file_content = output_text

if num_replaced > 0:
print "â—† ", num_replaced, " ", file_path.replace("\\", "/")
shutil.copy2(file_path, backup_fname)
output_file = open(file_path, "r+b")
output_file.read() # we do this way instead of “os.rename� to
preserve file creation date
output_file.seek(0)
output_file.write(output_text.encode("utf-8"))
output_file.truncate()
output_file.close()
else:
if print_no_change == True:
print "no change:", file_path

# os.remove(file_path)
# os.rename(temp_fname, file_path)

def process_file(dummy, current_dir, file_list):
current_dir = os.path.normpath(current_dir)
cur_dir_level = re.sub( "^" + re.escape(input_dir), "",
current_dir).count( os.sep)
cur_file_level = cur_dir_level + 1
if min_level <= cur_file_level <= max_level:
for a_file in file_list:
if re.search(r"\.html$", a_file, re.U) and
os.path.isfile(current_dir + re.escape(os.sep) + a_file):
replace_string_in_file(current_dir + os.sep + a_file)
# print "%d %s" % (cur_file_level, (current_dir + os.sep +
a_file))

input_dir = os.path.normpath(input_dir)

if (len(my_files) != 0):
for my_file in my_files:
replace_string_in_file(os.path.normpath(my_file) )
else:
os.path.walk(input_dir, process_file, "dummy")

print "Done."

On 08/04/2012 12:11, Xah Lee wrote:
<cut all>
Hi Xah,

You clearly didn't want help on this subject, as you really now how to
do it anyway. But having read your posts over the years, I'd like to
give you an observation on your persona, free of charge! :-)

You are actually a talented writer, some may find your occasional
profanity offensive but at least it highlights your frustration.
You are undoubtedly and proven a good mathematian and more important
than that self taught. You have a natural feel for design (otherwise you
would not clash with others view of programming).
You know a mixture of programming languages.

Whether you like it or not, you are in the perfect position to create a
new programming language and design a new programming paradigm.
Unhindered from all the legacy crap, that keep people like me behind (I
actually like BNF for example).

It is likely I am wrong, but if that is your destiny there is no point
fighting it.

Cheers and good luck,

Martin

Xah Lee <xahlee@gmail.com> wrote:
>hi guys,
>
>sorry am feeling a bit prolifit lately.
>
>today's show, is: 'Fuck Python'
>http://xahlee.org/comp/fuck_python.html
>
>------------------------------------
>Fuck Python
> By Xah Lee, 2012-04-08
>
>fuck Python.
>
>just fucking spend 2 hours and still going.
>
>here's the short story.
>
>so recently i switched to a Windows version of python. Now, Windows
>version takes path using win backslash, instead of cygwin slash. This
>fucking broke my find/replace scripts that takes a dir level as input.
>Because i was counting slashes.
>
>Ok no problem. My sloppiness. After all, my implementation wasn't
>portable. So, let's fix it. After a while, discovered there's the
>'os.sep'. Ok, replace "/" to 'os.sep', done. Then, bang, all hell
>went lose. Because, the backslash is used as escape in string, so any
>regex that manipulate path got fucked majorly.

When Microsoft created MS-DOS, they decided to use '\' as
the separator in file names. This was at a time when several
previously existing interactive operating systems were using
'/' as the file name separator and at least one was using '\'
as an escape character. As a result of Microsoft's decision
to use '\' as the separator, people have had to do extra work
to adapt programs written for Windows to run in non-Windows
environments, and vice versa. People have had to do extra work
to write software that is portable between these environments.
People have done extra work while creating tools to make writing
portable software easier. And people have to do extra work when
they use these tools, because using them is still harder than
writing portable code for operating systems that all used '/'
as their separator would have been.

If you added up the cost of all the extra work that people have
done as a result of Microsoft's decision to use '\' as the file
name separator, it would probably be enough money to launch the
Burj Khalifa into geosynchronous orbit.

So, when you say fuck Python, are you sure you're shooting at the
right target?

--
David Canzi | TIMTOWWTDI (tim-toe-woe-dee): There Is More Than One
| Wrong Way To Do It

["Followup-To:" header set to comp.lang.lisp.]
On 2012-04-08, David Canzi <dmcanzi@uwaterloo.ca> wrote:
> Xah Lee <xahlee@gmail.com> wrote:
>>hi guys,
>>
>>sorry am feeling a bit prolifit lately.
>>
>>today's show, is: 'Fuck Python'
>>http://xahlee.org/comp/fuck_python.html
>>
>>------------------------------------
>>Fuck Python
>> By Xah Lee, 2012-04-08
>>
>>fuck Python.
>>
>>just fucking spend 2 hours and still going.
>>
>>here's the short story.
>>
>>so recently i switched to a Windows version of python. Now, Windows
>>version takes path using win backslash, instead of cygwin slash. This
>>fucking broke my find/replace scripts that takes a dir level as input.
>>Because i was counting slashes.
>>
>>Ok no problem. My sloppiness. After all, my implementation wasn't
>>portable. So, let's fix it. After a while, discovered there's the
>>'os.sep'. Ok, replace "/" to 'os.sep', done. Then, bang, all hell
>>went lose. Because, the backslash is used as escape in string, so any
>>regex that manipulate path got fucked majorly.
>
> When Microsoft created MS-DOS, they decided to use '\' as
> the separator in file names.

This is false. The MS-DOS (dare I say it) "kernel" accepts both forward and
backslashes as separators.

The application-level choice was once configurable through a variable
in COMMAND.COM. Then they hard-coded it to backslash.

However, Microsoft operating systems continued to (and until this day)
recognize slash as a path separator.

Only, there are broken userland programs on Windows which don't know this.

> So, when you say fuck Python, are you sure you're shooting at the
> right target?

I would have to say, probably yes.

On 2012-04-08 17:03, David Canzi <dmcanzi@uwaterloo.ca> wrote:
> If you added up the cost of all the extra work that people have
> done as a result of Microsoft's decision to use '\' as the file
> name separator, it would probably be enough money to launch the
> Burj Khalifa into geosynchronous orbit.

So we have another contender for the Most Expensive One-byte Mistake?

Poul-Henning Kamp nominated the C/Unix guys:

http://queue.acm.org/detail.cfm?id=2010365

hp


--
_ | Peter J. Holzer | Deprecating human carelessness and
|_|_) | Sysadmin WSR | ignorance has no successful track record.
| | | hjp@hjp.at |
__/ | http://www.hjp.at/ | -- Bill Code on asrg@irtf.org

"David Canzi" <dmcanzi@uwaterloo.ca> wrote:
>Xah Lee <xahlee@gmail.com> wrote:

Please check whom you are replying to.

Do not feed the trolls, please.

jue

On 2012-04-08, Peter J. Holzer <hjp-usenet2@hjp.at> wrote:
> On 2012-04-08 17:03, David Canzi <dmcanzi@uwaterloo.ca> wrote:
>> If you added up the cost of all the extra work that people have
>> done as a result of Microsoft's decision to use '\' as the file
>> name separator, it would probably be enough money to launch the
>> Burj Khalifa into geosynchronous orbit.
>
> So we have another contender for the Most Expensive One-byte Mistake?

The one byte mistake in DOS and Windows is recognizing two characters as path
separators. All code that correctly handles paths is complicated by having to
look for a set of characters instead of just scanning for a byte.

> http://queue.acm.org/detail.cfm?id=2010365

DOS backslashes are already mentioned in that page, but alas it perpetuates the
clueless myth that DOS and windows do not recognize any other path separator.

Worse, the one byte Unix mistake being covered is, disappointingly, just a
clueless rant against null-terminated strings.

Null-terminated strings are infinitely better than the ridiculous encapsulation of length + data.

For one thing, if s is a non-empty null terminated string then, cdr(s) is also
a string representing the rest of that string without the first character,
where cdr(s) is conveniently defined as s + 1.

Not only can compilers compress storage by recognizing that string literals are
the suffixes of other string literals, but a lot of string manipulation code is
simplified, because you can treat a pointer to interior of any string as a
string.

Because they are recursively defined, you can do elegant tail recursion on null
terminated strings:

const char *rec_strchr(const char *in, int ch)
{
if (*in == 0)
return 0;
else if (*in == ch)
return in;
else
return rec_strchr(in + 1, ch);
}

length + data also raises the question: what type is the length field? One
byte? Two bytes? Four? And then you have issues of byte order. Null terminated
C strings can be written straight to a binary file or network socket and be
instantly understood on the other end.

Null terminated strings have simplified all kids of text manipulation, lexical
scanning, and data storage/communication code resulting in immeasurable
savings over the years.

> so recently i switched to a Windows version of python. Now, Windows
> version takes path using win backslash, instead of cygwin slash. This
> fucking broke my find/replace scripts that takes a dir level as input.
> Because i was counting slashes.
>
> Ok no problem. My sloppiness. After all, my implementation wasn't
> portable. So, let's fix it. After a while, discovered there's the
> 「os.sep�. Ok, replace 「"/"� to 「os.sep�, done. Then, bang, all hell
> went lose. Because, the backslash is used as escape in string, so any
> regex that manipulate path got fucked majorly.

....

> sorry am feeling a bit prolifit lately.

Well, you should learn programming instead of being 'prolifit'.

You could replace all backslashes with forward slashes after you get
paths from OS:

>>> "c:\\windpws\\sux".replace('\\', '/')
'c:/windpws/sux'

After this your code will work as is. Note that Windows accepts forward
slashes as path names, so you don't need to convert them back.

> This fix is supposed to be done in 10 min.

Well, I could fix it in 10 seconds. Maybe because I'm a programmer
rather than a 'prolifit'.

P.S. This was just a "Fuck Xah Lee" essay, nothing personal.
It is a part of a series.

"Kaz Kylheku" <kaz@kylheku.com> wrote in message
news:20120408114313.85@kylheku.com...

> Worse, the one byte Unix mistake being covered is, disappointingly, just a
> clueless rant against null-terminated strings.
>
> Null-terminated strings are infinitely better than the ridiculous
> encapsulation of length + data.
>
> For one thing, if s is a non-empty null terminated string then, cdr(s) is
> also
> a string representing the rest of that string without the first character,
> where cdr(s) is conveniently defined as s + 1.

If strings are represented as (ptr,length), then a cdr(s) would have to
return (ptr+1,length-1), or (nil,0) if s was one character. No big deal.

(Note I saw your post in comp.lang.python; I don't about any implications of
that for Lisp.)

And if, instead, you want to represent all but the last character of the
string, then it's just (ptr,length-1). (Some checking is needed around empty
strings, but similar checks are needed around s+1.)

In addition, if you want to represent the middle of a string, then it's also
very easy: (ptr+a,b).

> Not only can compilers compress storage by recognizing that string
> literals are
> the suffixes of other string literals, but a lot of string manipulation
> code is
> simplified, because you can treat a pointer to interior of any string as a
> string.

Yes, the string "bart" also contains "art", "rt" and "t". But with counted
strintgs, it can also contain "bar", "ba", "b", etc....

There are a few advantages to counted strings too...

> length + data also raises the question: what type is the length field? One
> byte? Two bytes? Four?

Depends on the architecture. But 4+4 for 32-bits, and 8+8 bytes for 64-bits,
I would guess, for general flex strings of any length.

There are other ways of encoding a length.

(For example I use one short string type of maximum M characters, but the
current length N is encoded into the string, without needing any extra count
byte (by fiddling about with the last couple of bytes). If you're trying to
store a short string in an 8-byte field in a struct, then this will let you
use all 8 bytes; a zero-terminated one, only 7.)

> And then you have issues of byte order.

Which also affects every single value of more than one byte.

> Null terminated
> C strings can be written straight to a binary file or network socket and
> be
> instantly understood on the other end.

But they can't contains nulls!

> Null terminated strings have simplified all kids of text manipulation,
> lexical
> scanning, and data storage/communication code resulting in immeasurable
> savings over the years.

They both have their uses.

--
Bartc

On Sun, 08 Apr 2012 19:14:45 +0000, Kaz Kylheku wrote:

> The one byte mistake in DOS and Windows is recognizing two characters as path
> separators. All code that correctly handles paths is complicated by having to
> look for a set of characters instead of just scanning for a byte.

It's worse when you consider that the "standard" Windows encoding for
Japanese is Shift-JIS, which allows a \x5c character (normally backslash,
but which also doubles as the Yen character) to occur as the second byte
of a multi-byte sequence.

Which means that you can't write "encoding-agnostic" pathname-handling
functions.

> Null-terminated strings are infinitely better than the ridiculous
> encapsulation of length + data.

Windows provides the worst of both worlds. The Windows API uses
null-terminated strings, but the NT API on which the Windows subsystem
runs uses length+data. So you can use the NT API to e.g. create registry
keys containing an embedded null, so the Windows API can't read them (or
rename them, or delete them).

On Sun, 08 Apr 2012 04:11:20 -0700, Xah Lee wrote:

> Ok no problem. My sloppiness. After all, my implementation wasn't
> portable. So, let's fix it. After a while, discovered there's the
> os.sep. Ok, replace "/" to os.sep, done. Then, bang, all hell
> went lose. Because, the backslash is used as escape in string, so any
> regex that manipulate path got fucked majorly. So, now you need to
> find a quoting mechanism.

if os.altsep is not None:
sep_re = '[%s%s]' % (os.sep, os.altsep)
else:
sep_re = '[%s]' % os.sep

But really, you should be ranting about regexps rather than Python.
They're convenient if you know exactly what you want to match, but a
nuisance if you need to generate the expression based upon data which is
only available at run-time (and re.escape() only solves one very specific
problem).

Em domingo, 8 de abril de 2012 14h03min28s UTC-3, David Canzi escreveu:
> Xah Lee <xahlee@gmail.com> wrote:
> >hi guys,
> >
> >sorry am feeling a bit prolifit lately.
> >
> >today's show, is: 'Fuck Python'
> >http://xahlee.org/comp/fuck_python.html
> >
> >------------------------------------
> >Fuck Python
> > By Xah Lee, 2012-04-08
> >
> >fuck Python.
> >
> >just fucking spend 2 hours and still going.
> >
> >here's the short story.
> >
> >so recently i switched to a Windows version of python. Now, Windows
> >version takes path using win backslash, instead of cygwin slash. This
> >fucking broke my find/replace scripts that takes a dir level as input.
> >Because i was counting slashes.
> >
> >Ok no problem. My sloppiness. After all, my implementation wasn't
> >portable. So, let's fix it. After a while, discovered there's the
> >'os.sep'. Ok, replace "/" to 'os.sep', done. Then, bang, all hell
> >went lose. Because, the backslash is used as escape in string, so any
> >regex that manipulate path got fucked majorly.
>
> When Microsoft created MS-DOS, they decided to use '\' as
> the separator in file names. This was at a time when several
> previously existing interactive operating systems were using
> '/' as the file name separator and at least one was using '\'
> as an escape character. As a result of Microsoft's decision
> to use '\' as the separator, people have had to do extra work
> to adapt programs written for Windows to run in non-Windows
> environments, and vice versa. People have had to do extra work
> to write software that is portable between these environments.
> People have done extra work while creating tools to make writing
> portable software easier. And people have to do extra work when
> they use these tools, because using them is still harder than
> writing portable code for operating systems that all used '/'
> as their separator would have been.

yes, absolutely. But you got 2 inaccuracies there: 1) Microsoft didn't create DOS; 2) fucking DOS was written in C, and guess what, it uses \ as escape character. Fucking microsoft.


> So, when you say fuck Python, are you sure you're shooting at the
> right target?

I agree. Fuck winDOS and fucking microsoft.

namekuseijin <namekuseijin@gmail.com> writes:

>> When Microsoft created MS-DOS, they decided to use '\' as
>> the separator in file names. This was at a time when several
>> previously existing interactive operating systems were using
>> '/' as the file name separator and at least one was using '\'
>> as an escape character. As a result of Microsoft's decision
>> to use '\' as the separator, people have had to do extra work
>> to adapt programs written for Windows to run in non-Windows
>> environments, and vice versa. People have had to do extra work
>> to write software that is portable between these environments.
>> People have done extra work while creating tools to make writing
>> portable software easier. And people have to do extra work when
>> they use these tools, because using them is still harder than
>> writing portable code for operating systems that all used '/'
>> as their separator would have been.
>
> yes, absolutely. But you got 2 inaccuracies there: 1) Microsoft
> didn't create DOS; 2) fucking DOS was written in C, and guess what, it
> uses \ as escape character. Fucking microsoft.

Actually, it's all due to a lamentable transcription error. You have to
understand that at the time, computers didn't have big disk space (if
they had disks at all), and didn't have the IP connectivity we have
nowadays. They didn't even have a lot printers, printers being as
costly as computers, if not more. (At least compared to small cheap
computers).

Therefore documentation wasn't on-line, and certainly not in-line.
People had to write it down by hand, with a pen or pencil, making little
marks on sheets of paper. (Happily it was already ballpens, not
Quill pens).

So what happenned was that some student learned about unix, and it's
convention of using dashes to prefix options (so that they're not
confused by file names, which assumedly don't start with a dash, or if
they do, can be written as ./-dash-file instead). Unfortunately, that
student wasn't too good at caligraphy, and wrote his dashes slightly
slanted upward. When they wanted to copy the convention on the early
versions of DOS, they had a look at those HAND-WRITTEN notes, and
misread the dashes for slashes, what was ls -l was read as ls /l.
That's how DOS commands got the convention of using slashes to start
options. Then of course, confusion was possible with pathname
separators, so they had to use another character, and backslash was an
obvious, if fateful, choice.

--
__Pascal Bourguignon__ http://www.informatimago.com/
A bad day in () is better than a good day in {}.

Xah Lee wrote:

« http://xahlee.org/comp/fuck_python.html »

David Canzi wrote

«When Microsoft created MS-DOS, they decided to use '\' as the
separator in file names. Â*This was at a time when several previously
existing interactive operating systems were using '/' as the file name
separator and at least one was using '\' as an escape character. Â*As a
result of Microsoft's decision to use '\' as the separator, people
have had to do extra work to adapt programs written for Windows to run
in non-Windows environments, and vice versa. Â*People have had to do
extra work to write software that is portable between these
environments. People have done extra work while creating tools to
make writing portable software easier. Â*And people have to do extra
work when they use these tools, because using them is still harder
than writing portable code for operating systems that all used '/' as
their separator would have been.»

namekuseijin wrote:

> yes, absolutely. Â*But you got 2 inaccuracies there: Â*1) Microsoft didn't create DOS; 2) fucking DOS was written in C, and guess what, it uses \ as escape character. Â*Fucking microsoft.
>
> > So, when you say fuck Python, are you sure you're shooting at the
> > right target?
>
> I agree. Â*Fuck winDOS and fucking microsoft.

No. The choice to use backslash than slash is actually a good one.

because, slash is one of the useful char, far more so than backslash.
Users should be able to use that for file names.

i don't know the detailed history of path separator, but if i were to
blame, it's fuck unix. The entirety of unix, unix geek, unixers, unix
fuckheads. Fuck unix.

〈On Unix Filename Characters Problem〉
http://xahlee.org/UnixResource_dir/w...ame_chars.html

〈On Unix File System's Case Sensitivity〉
http://xahlee.org/UnixResource_dir/_/fileCaseSens.html

〈UNIX Tar Problem: File Length Truncation, Unicode Name Support〉
http://xahlee.org/comp/unix_tar_problem.html

〈What Characters Are Not Allowed in File Names?〉
http://xahlee.org/mswin/allowed_char...ile_names.html

〈Unicode Support in File Names: Windows, Mac, Emacs, Unison, Rsync,
USB, Zip〉
http://xahlee.org/mswin/unicode_support_file_names.html

〈The Nature of the Unix Philosophy〉
http://xahlee.org/UnixResource_dir/writ/unix_phil.html

Xah

>> Ok no problem. My sloppiness. After all, my implementation wasn't
>> portable. So, let's fix it. After a while, discovered there's the
>> os.sep. Ok, replace "/" to os.sep, done. Then, bang, all hell
>> went lose. Because, the backslash is used as escape in string, so any
>> regex that manipulate path got fucked majorly. So, now you need to
>> find a quoting mechanism.
>
> if os.altsep is not None:
> sep_re = '[%s%s]' % (os.sep, os.altsep)
> else:
> sep_re = '[%s]' % os.sep
>
> But really, you should be ranting about regexps rather than Python.
> They're convenient if you know exactly what you want to match, but a
> nuisance if you need to generate the expression based upon data which is
> only available at run-time (and re.escape() only solves one very specific
> problem).

It isn't a problem of regular expressions, but a problem of syntax for
specification of regular expressions (i.e. them being specified as a
string).

Common Lisp regex library cl-ppcre allows to specify regex via a parse
tree. E.g. "(foo[/\\]bar)" becomes

(:REGISTER (:SEQUENCE "foo" (:CHAR-CLASS #\/ #\\) "bar"))

This is more verbose, but totally unambiguous and requires no escaping.

So this definitely is a problem of Python's regex library, and a problem
of lack of support for nice parse tree representation in code.

cl-ppcre supports both textual perl-compatible regex specification and
parse tree. I would start with a simple string specification, then when
shit hits fan I can call cl-ppcre:arse-string to get those parse trees
and replaces forward slash with back slash. Moreover, I can
automatically convert regexes:

(defun scan-auto/ (regex target-string)
(let ((fixed-parse-tree (subst '(:char-class #\/ #\\) '(:char-class #\/)
(cl-ppcre:arse-string regex)
:test 'equal)))
(cl-ppcre:scan-to-strings fixed-parse-tree target-string)))


CL-USER> (scan-auto/ "foo[/]bar" "foo\\bar")
"foo\\bar"
#()