Re: re.search when used within an if/else fails
Dennis Lee Bieber wlfr...@ix.netcom.com wrote: Unless there has been a major change in the parser... (I still don't have Python 3.x installed) I believe tab is expanded to 8-spaces -- NOT TO NEXT MULTIPLE OF 8... Certainly in Python 2.7 that's not the case: the tab expands to the next multiple of 8 spaces. if 1: ... print yes # space + tab ... print no # eight spaces ... yes no If tab expanded to exactly 8 spaces the leading space would have forced an indentation error, but it didn't. -- Duncan Booth http://kupuguy.blogspot.com -- http://mail.python.org/mailman/listinfo/python-list
RE: re.search when used within an if/else fails
Ramit Prasad wrote: Dennis Lee Bieber wrote: Unless there has been a major change in the parser... (I still don't have Python 3.x installed) I believe tab is expanded to 8-spaces -- NOT TO NEXT MULTIPLE OF 8... A tab is *one* character. Your *editor* may show tabs visually expanded or convert them to spaces. This is entirely editor dependent. My current (python) editor, does expands tabs to the next *multiple* of 4. It helps keep code aligned, and I have no need for 4 hard spaced tabs without regards to alignment (yet). I have had editors that did 4 hard spaced tabs, so it might be a developer/application preference. with open(r'c:\ramit\mix_tab_space.txt')as f: ... d = f.read() ... print repr(d) '\tblah\ntest\n\t' print d[0] + 'goo' goo print repr(d[0] + 'goo') '\tgoo' Apologies, I missed that it was talking about the parser and not editor/file. Please disregard my previous post. ~Ramit This email is confidential and subject to important disclaimers and conditions including on offers for the purchase or sale of securities, accuracy and completeness of information, viruses, confidentiality, legal privilege, and legal entity disclaimers, available at http://www.jpmorgan.com/pages/disclosures/email. -- http://mail.python.org/mailman/listinfo/python-list
RE: re.search when used within an if/else fails
Dennis Lee Bieber wrote: Unless there has been a major change in the parser... (I still don't have Python 3.x installed) I believe tab is expanded to 8-spaces -- NOT TO NEXT MULTIPLE OF 8... A tab is *one* character. Your *editor* may show tabs visually expanded or convert them to spaces. This is entirely editor dependent. My current (python) editor, does expands tabs to the next *multiple* of 4. It helps keep code aligned, and I have no need for 4 hard spaced tabs without regards to alignment (yet). I have had editors that did 4 hard spaced tabs, so it might be a developer/application preference. with open(r'c:\ramit\mix_tab_space.txt')as f: ... d = f.read() ... print repr(d) '\tblah\ntest\n\t' print d[0] + 'goo' goo print repr(d[0] + 'goo') '\tgoo' So the first is 8+4 = 12 spaces, the second is 2+8+4 = 14 spaces. Does 2 + tab + 2 vs 4 + tab vs tab + 4 succeed? That would confirm the treatment. The main concern with mixed tab and spaces, as I recall, was due to having /editors/ and /terminals/ configured to show tab as a four space (or anything other than an eight space) increment; so visually four spaces and one tab might look the same... One user might have the editor showing 4-space indents on tab but entering text using 4 spaces on input -- which now is mis-aligned if the source file HAD tab in it. ~Ramit This email is confidential and subject to important disclaimers and conditions including on offers for the purchase or sale of securities, accuracy and completeness of information, viruses, confidentiality, legal privilege, and legal entity disclaimers, available at http://www.jpmorgan.com/pages/disclosures/email. -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
I agree. Being relatively new to python, i was not sure of quirks so i posted the original code. I did find the real issue, as I found another loop that was not being executed properly. It turns out that if the indent started with spaces and ended with tabs, neither eclipse or command line execution would complain. where as if the indent begins with tabs and has spaces in the middle the tools will complain of indentation issues. i have found that the vi plugin for python is the culprit here. when the plugin does block indentation, the result is indents that begin with spaces. if i disable the vi plugin and use the regular eclipse editor these issues go away. with other languages i always expand tabs to spaces. the vi plugin does do this properly. if i change all indents to be spaces only will python behave? i inherited a good deal of the code that i am using, which is tab based. thanks kevin On Wednesday, November 21, 2012 11:00:50 PM UTC-6, Chris Angelico wrote: On Thu, Nov 22, 2012 at 3:41 AM, Kevin T wrote: I went back and tried version a again, blam it is/does work now ?!?!? This is why the Short, Self-Contained, Correct Example is so important. See http://sscce.org/ for some info on that. I often find -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
On Wed, Nov 28, 2012 at 12:39 PM, Kevin T kevini...@gmail.com wrote: with other languages i always expand tabs to spaces. the vi plugin does do this properly. if i change all indents to be spaces only will python behave? i inherited a good deal of the code that i am using, which is tab based. Yes, it's best to use either tabs-only or spaces-only. Quoting from PEP 8 on the subject: Never mix tabs and spaces. The most popular way of indenting Python is with spaces only. The second-most popular way is with tabs only. Code indented with a mixture of tabs and spaces should be converted to using spaces exclusively. When invoking the Python command line interpreter with the -t option, it issues warnings about code that illegally mixes tabs and spaces. When using -tt these warnings become errors. These options are highly recommended! For new projects, spaces-only are strongly recommended over tabs. Most editors have features that make this easy to do. I thought the prohibition against mixing tabs and spaces was made more strict in Python 3, but I can't find any reference to that now. Probably I was mistaken. -- http://mail.python.org/mailman/listinfo/python-list
Re: Re: re.search when used within an if/else fails
On 11/28/2012 01:57 PM, Ian Kelly wrote: Yes, it's best to use either tabs-only or spaces-only. Quoting from PEP 8 on the subject: Never mix tabs and spaces. The most popular way of indenting Python is with spaces only. The second-most popular way is with tabs only. Code indented with a mixture of tabs and spaces should be converted to using spaces exclusively. When invoking the Python command line interpreter with the -t option, it issues warnings about code that illegally mixes tabs and spaces. When using -tt these warnings become errors. These options are highly recommended! For new projects, spaces-only are strongly recommended over tabs. Most editors have features that make this easy to do. I thought the prohibition against mixing tabs and spaces was made more strict in Python 3, but I can't find any reference to that now. Probably I was mistaken. I'm only entering this thread now so I'm not really in context, but you're correct; in Python 3, -tt is set by default, which makes illegal mixing an error. However, not all mixing is illegal: what it means by code that illegally mixes tabs and spaces is code whose interpretation differs depending upon the interpretation of the tab width. While I'm not going to go test it, I think that if you, say, indent from the first to the second level with tabs (consistently), indent from the second to third level with spaces (consistently), and indent from the third to fourth level with tabs (consistently), it should not complain. Or perhaps I should say it should complain that you're a bad person and should feel bad, but it won't. :-) (In fact, you could indent one block at the second level with tabs and another with spaces.) Evan signature.asc Description: OpenPGP digital signature -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
On Wed, 28 Nov 2012 11:39:48 -0800, Kevin T wrote: with other languages i always expand tabs to spaces. the vi plugin does do this properly. if i change all indents to be spaces only will python behave? i inherited a good deal of the code that i am using, which is tab based. Python will behave correctly if you use all spaces, or all tabs, for indents. If you mix spaces and tabs, anything can happen. For this reason, Python 3 is more strict and will raise an explicit error when it detects mixed spaces/tabs in an indent. See also the tabnanny tool provided with Python: [steve@ando ~]$ python -m tabnanny Usage: /usr/local/lib/python2.7/tabnanny.py [-v] file_or_directory ... -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
On Wed, 28 Nov 2012 14:08:15 -0600, Evan Driscoll wrote: I'm only entering this thread now so I'm not really in context, but you're correct; in Python 3, -tt is set by default, which makes illegal mixing an error. However, not all mixing is illegal: what it means by code that illegally mixes tabs and spaces is code whose interpretation differs depending upon the interpretation of the tab width. While I'm not going to go test it, I think that if you, say, indent from the first to the second level with tabs (consistently), indent from the second to third level with spaces (consistently), and indent from the third to fourth level with tabs (consistently), it should not complain. Correct, which disappoints me. Testing with Python 3: py if True: ... if True: # tab ... pass # tab, then four spaces ... py I would prefer that the pass line would fail with an illegal indent, but it does not. But at least the following fails cleanly: py if True: ... if True: # tab ... pass # tab, then four spaces ... pass # two spaces, tab, four spaces File stdin, line 4 pass # two spaces, tab, four spaces ^ TabError: inconsistent use of tabs and spaces in indentation Or perhaps I should say it should complain that you're a bad person and should feel bad, but it won't. :-) (In fact, you could indent one block at the second level with tabs and another with spaces.) I don't mind different blocks using different indentation. You have always been able to do this: py if True: ... pass # eight spaces ... py if True: ... pass # two spaces ... py If you don't like that, don't do it! Consistent indentation globally per file is a matter for coding conventions. However, I think that within a single block, Python should enforce all tabs or all spaces. Perhaps it would be nice if Python honoured a directive setting indent style to spaces or indents, as it honours source code encoding lines: # -*- indent: mode -*- Where mode could be one of: space[s]Only accept spaces in indentation tab[s] Only accept tabs in indentation mixed Accept mixed tabs and spaces, but only if consistent with mixed the default for backward compatibility. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Tabs/spaces for indentation (was Re: re.search when used within an if/else fails)
On Thu, Nov 29, 2012 at 8:39 AM, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote: Perhaps it would be nice if Python honoured a directive setting indent style to spaces or indents, as it honours source code encoding lines: # -*- indent: mode -*- Where mode could be one of: space[s]Only accept spaces in indentation tab[s] Only accept tabs in indentation mixed Accept mixed tabs and spaces, but only if consistent with mixed the default for backward compatibility. I don't know that it needs to be a declaration like that; character encodings are critical to parsing the file, but newline-followed-by-tab and newline-followed-by-space are unambiguous. But it would be of value to have something like that, as editors could then be configured to respect it - set the editor to turn tab-key into N spaces but only if indent tab is not set, for instance. The question is, is it worth it? The main value would be when you're editing someone else's code. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
On Wed, Nov 28, 2012 at 5:20 PM, Dennis Lee Bieber wlfr...@ix.netcom.comwrote: On 28 Nov 2012 21:39:03 GMT, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info declaimed the following in gmane.comp.python.general: py if True: ... if True: # tab ... pass # tab, then four spaces ... pass # two spaces, tab, four spaces File stdin, line 4 pass # two spaces, tab, four spaces ^ TabError: inconsistent use of tabs and spaces in indentation Unless there has been a major change in the parser... (I still don't have Python 3.x installed) I believe tab is expanded to 8-spaces -- NOT TO NEXT MULTIPLE OF 8... Next multiple of 8 is correct, according to the docs: Tabs are replaced (from left to right) by one to eight spaces such that the total number of characters up to and including the replacement is a multiple of eight (this is intended to be the same rule as used by Unix). The total number of spaces preceding the first non-blank character then determines the line’s indentation. Indentation cannot be split over multiple physical lines using backslashes; the whitespace up to the first backslash determines the indentation. http://docs.python.org/3/reference/lexical_analysis.html#indentation Testing Steven's formulation with Python 2, I find that it runs without comment without the -tt option, but it raises the TabError with the -tt option. -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
On Nov 20, 1:37 pm, Ian Kelly ian.g.ke...@gmail.com wrote:
On Tue, Nov 20, 2012 at 12:09 PM, Kevin T kevini...@gmail.com wrote:
#if re.search( rsrvd, sigName ) : #version a
#if re.search( rsrvd, sigName ) == None : #version b
if re.search( rsrvd, sigName ) is None : #version bb
print sigName
newVal = %s%s % ('1'*signal['bits'] , newVal )
#else: #version c
if re.search( rsrvd, sigName ) != None : #version d
print sigName
newVal = %s%s % ( '0'*signal['bits'], newVal )
i can use either version a/b the else clause (version c) will not execute.
fortunately, with version bb, the else clause will execute!!
There must be some other difference in your testing. I don't have
Python 2.4 available, but I tried your version a in both Python 2.3
and 2.5 using made-up values for sigName, and the else clause is
executed in both.
I went back and tried version a again, blam it is/does work now ?!?!?
I am not sure what changed but version a was the original code that
wouldn't work. All the examples i had read, showed version a as a
working version. I spent significant time trying version a with
parens, spacing changes, different regex values to no avail. hence
the creation of all the other versions.
thanks for your help.
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Re: re.search when used within an if/else fails
On Thu, Nov 22, 2012 at 3:41 AM, Kevin T kevini...@gmail.com wrote: I went back and tried version a again, blam it is/does work now ?!?!? I am not sure what changed but version a was the original code that wouldn't work. All the examples i had read, showed version a as a working version. I spent significant time trying version a with parens, spacing changes, different regex values to no avail. hence the creation of all the other versions. This is why the Short, Self-Contained, Correct Example is so important. See http://sscce.org/ for some info on that. I often find myself stuck, begin typing up a post to some appropriate mailing list, and while coalescing the problem into its smallest possible form, end up finding the cause directly. More often than not, I end up discarding the message unsent (though sometimes, I end up submitting a patch to the language/library maintainers, eg improving the docs so it's more visible next time). In any case, if you can copy and paste the exact code and error, it's a lot easier for us to replicate your problem. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
On Monday, November 19, 2012 7:29:20 PM UTC-6, Steven D'Aprano wrote:
On Tue, 20 Nov 2012 01:24:54 +, Steven D'Aprano wrote:
- use if something is None, not == None.
Steven
i will not include line #'s in the future, point taken
i will change ==/!= to is/is not as most people pointed out.
there is no else because it doesn't work.
i used eclipse in debug mode and a command line execution of the code, both
behave the same way
#if re.search( rsrvd, sigName ) : #version a
#if re.search( rsrvd, sigName ) == None : #version b
if re.search( rsrvd, sigName ) is None : #version bb
print sigName
newVal = %s%s % ('1'*signal['bits'] , newVal )
#else: #version c
if re.search( rsrvd, sigName ) != None : #version d
print sigName
newVal = %s%s % ( '0'*signal['bits'], newVal )
i can use either version a/b the else clause (version c) will not execute.
fortunately, with version bb, the else clause will execute!!
thanks for the input all..
kevin
Now if i change
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Re: re.search when used within an if/else fails
On Tue, Nov 20, 2012 at 12:09 PM, Kevin T kevini...@gmail.com wrote:
#if re.search( rsrvd, sigName ) : #version a
#if re.search( rsrvd, sigName ) == None : #version b
if re.search( rsrvd, sigName ) is None : #version bb
print sigName
newVal = %s%s % ('1'*signal['bits'] , newVal )
#else: #version c
if re.search( rsrvd, sigName ) != None : #version d
print sigName
newVal = %s%s % ( '0'*signal['bits'], newVal )
i can use either version a/b the else clause (version c) will not execute.
fortunately, with version bb, the else clause will execute!!
There must be some other difference in your testing. I don't have
Python 2.4 available, but I tried your version a in both Python 2.3
and 2.5 using made-up values for sigName, and the else clause is
executed in both.
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Re: re.search when used within an if/else fails
On Tue, Nov 20, 2012 at 12:37 PM, Ian Kelly ian.g.ke...@gmail.com wrote:
On Tue, Nov 20, 2012 at 12:09 PM, Kevin T kevini...@gmail.com wrote:
#if re.search( rsrvd, sigName ) : #version a
#if re.search( rsrvd, sigName ) == None : #version b
if re.search( rsrvd, sigName ) is None : #version bb
print sigName
newVal = %s%s % ('1'*signal['bits'] , newVal )
#else: #version c
if re.search( rsrvd, sigName ) != None : #version d
print sigName
newVal = %s%s % ( '0'*signal['bits'], newVal )
i can use either version a/b the else clause (version c) will not execute.
fortunately, with version bb, the else clause will execute!!
There must be some other difference in your testing. I don't have
Python 2.4 available, but I tried your version a in both Python 2.3
and 2.5 using made-up values for sigName, and the else clause is
executed in both.
It should be noted, however, that version a is the logical *inverse*
of both b and bb. With version a, you're testing for the logical
truth of the re.search result; it will be true if it is *not* None.
With the other two you are testing that the result *is* None.
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re.search when used within an if/else fails
python version 2.4.3, yes i know that it is old. getting the sysadmin to update the OS requires a first born. with the following code.. for signal in register['signals'] : 351 sigName = signal['functionName'] 352 if re.search( rsrvd, sigName ) == None : 353 print sigName 354 newVal = %s%s % ( '1'*signal['bits'] , newVal ) #prepend 0's 355 if re.search( rsrvd, sigName ) != None : 356 print sigName 357 newVal = %s%s % ( '0'*signal['bits'], newVal ) regardless of how i code line 352, i can not EVER use an else clause with it. if i use an else clause, the else will NEVER get executed... has any one experienced anything like this behavior? any suggestions? the above code works but... why should i have to code it like this? kevin -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
On 2012-11-19 23:43, Kevin T wrote: python version 2.4.3, yes i know that it is old. getting the sysadmin to update the OS requires a first born. with the following code.. for signal in register['signals'] : 351 sigName = signal['functionName'] 352 if re.search( rsrvd, sigName ) == None : 353 print sigName 354 newVal = %s%s % ( '1'*signal['bits'] , newVal ) #prepend 0's 355 if re.search( rsrvd, sigName ) != None : 356 print sigName 357 newVal = %s%s % ( '0'*signal['bits'], newVal ) regardless of how i code line 352, i can not EVER use an else clause with it. if i use an else clause, the else will NEVER get executed... has any one experienced anything like this behavior? any suggestions? the above code works but... why should i have to code it like this? Have you checked the indentation? There may be a mixture of tabs and spaces. A couple of points: 1. You should be using is None and is not None instead of == None and != None. 2. You don't need to use regex. Use rsrvd in sigName and rsrvd not in sigName. -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
On Tue, 20 Nov 2012 01:24:54 +, Steven D'Aprano wrote: Your code is mangled to the point of unreadability. Ah, never mind, that's *my* fault, not yours. Or rather, my news reader software. Sorry about the noise. The rest of my post still stands: - simplify your example to the simplest example that we can run http://sscce.org/ - don't put line numbers at the start of lines - your code doesn't have an else clause - use if something is None, not == None. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search when used within an if/else fails
On Mon, 19 Nov 2012 15:43:10 -0800, Kevin T wrote: python version 2.4.3, yes i know that it is old. getting the sysadmin to update the OS requires a first born. with the following code.. for signal in register['signals'] : 351 sigName = signal['functionName'] 352 if re.search( rsrvd, sigName ) == None : 353 print sigName 354 newVal = %s%s % ( '1'*signal['bits'] , newVal ) #prepend 0's 355 if re.search( rsrvd, sigName ) != None : 356 print sigName 357 newVal = %s%s % ( '0'*signal['bits'], newVal ) Your code is mangled to the point of unreadability. Please resend, and make sure you send it as PLAIN TEXT and not as HTML (rich text), since many mail programs feel that they are allowed to arbitrarily rewrap HTML text however they like. Preferably simplify your example to the simplest example that we can run: http://sscce.org/ Being able to run it means you shouldn't put line numbers on the left. If you must draw our attention to a specific line, use a comment. This isn't 1975 and we're not programming in BASIC. # BAD don't do this: 350 do_this(x) 351 do_that(y, z) 352 if something: 353 do_something_else(x, y, z) # GOOD do this: do_this(x) do_that(y, z) if something: # LINE 352 do_something_else(x, y, z) regardless of how i code line 352, i can not EVER use an else clause with it. if i use an else clause, the else will NEVER get executed... The code you show doesn't actually have an `else` clause, which might explain why it doesn't get executed. By the way, you should not write if something == None, always use if something is None or is not None. Technically, there are some exceptions but if you have to ask what they are, you don't need to know *wink* -- Steven -- http://mail.python.org/mailman/listinfo/python-list
