Mailman 3 June 2011 - docs

[issue11553] Docs for: import, packages, site.py, .pth files
by Graham Wideman Jan. 24, 2020

Jan. 24, 2020

New submission from Graham Wideman <initcontact(a)grahamwideman.com>: The overall scope of this issue is that current Python documentation gives vague, sometimes incorrect, information about the set of Python features involved in modularizing functionality. This issue presents an obstacle to programmers making smooth transitions from a single module, to collections of modules and packages, then on to neatly organized common packages shared between projects. The problem affects documentation of: import and from...import statements ------------------------------------ The Language Reference is way too complicated for the mainstream case. Exactly what variants of arguments are possible, and what are their effects? What are the interactions with package features, such as whether or not modules have been explicitly imported into package __init_.py? sys.path --------- Typical consituents; range of alternatives for adding more dirs Module site.py -------------- Multiple serious errors in the file docstring, relating to site-packages directories and .pth files .pth files ----------- Incorrectly described in site.py, and then vaguely described in other docs. Are .pth files processed everywhere on sys.path? Can they be interative? (No to both). package structure ----------------- Details of package structure have evidently changed over Python versions. Current docs are unclear on points such as: -- is __init__.py needed on subpackage directories? -- the __all__ variable: Does it act generally to limit visibility of a module or package's attributes, or does pertain only to the 'from...import *' statement? Details: ========= Language Reference ------------------- http://docs.python.org/py3k/reference/simple_stmts.html#the-import-statement The description of the import statement is extensive, but dauntingly complicated for the reader trying to understand the mainstream case of simply importing modules or packages that are on sys.path. This is because the algorithm for finding modules tries numerous esoteric strategies before falling back on the plain-old-file-system method. (Even now that I have a good understanding of the plain-old-file variations of import, I reread this and find it hard to comprehend, and disorganized and incomplete in presenting the available variations of the statement.) Grammar issue: the grammar shown for the import statement shows: relative_module ::= "."* module | "."+ ... which implies that relative module could have zero leading dots. I believe an actual relative path is required to have at least one dot (PEP 328). Evidently, in this grammar, 'relative_module' really means "relative or absolute path to module or package", so it would be quite helpful to change to: relative_path ::= "."+ module | "."+ from_path ::= (relative_path | module) etc. (Really 'module' is not quite right here either since it's used to mean module-or-package.) site.py: -------- Module site.py implements the site-package related features. The docstring has multiple problems with consequences in other docs. 1. Does not mention user-specific site-package directories (implemented by addusersitepackages() ) 2. Seriously misleading discussion of .pth files. In the docstring the example shows using pth files, called "package configuration files" in their comments, to point to actual package directories bar and foo located within the site-packages directory. This is an absolutely incorrect use of pth files: If foo and bar are packages in .../site-packages/, they do not need to be pointed to, they are already on sys.path. If the package dirs ARE pointed to by foo.pth and bar.pth, the modules inside them will be exposed directly to sys.path, possibly precipitating name collisions. Further, programmers following this example will create packages in which import statements will appear to magically perform relative imports without leading dots, leading to confusion over how the import statement is supposed to work. It may be that this discussion is held over from a time when "package" perhaps meant "Just a Bunch of Files in a Directory"? 3. The docstring (or other docs) should make clear that .pth files are ONLY processed within site-package directories (ie: only by site.py). 4. Bug: Minor: In addsitepackages(), the library directory for Windows (the else clause) is shown as lower-case 'lib' instead of 'Lib'. This has some possibility of causing problems when running from a case-sensitive server. In any case, if read as documentation it is misleading. Tutorial --------- 6. Modules: http://docs.python.org/py3k/tutorial/modules.html 1. Discussion (6.1.2. The Module Search Path) is good as far as it goes, but it doesn't mention the site-package directories. 2. Section 6.4. Packages: Discussion of __init__.py does describe the purpose of these files. However, the discussion in relation to subpackages should mention that for subdirectories to be accessible they must in fact be made into subpackages. I.e.: there is not form of import that can reach into a subdir of a package *unless* it's flagged as a subpackage using __init__.py. I have read elsewhere that there were some versions of Python where __init__.py was not needed on subdirs within a package. 3. Section 6.4. Packages: The discussion of __all__ should note that it works *only* in conjunction with 'from...import *', and is not a general mechanism for limiting visibility of attributes. Attributes not in the __all__ list are still accessible using other forms of import. 4. Section 6.4. Packages: "Note that when using from package import item" and following. Draws a contrast between: from package import item vs import item.subitem.subsubitem However, this muddles the roles of the arguments to import, and notably uses 'item' in two different ways. Instead the discussion can be presented as a comparison of: from PackageOrModule import ModuleOrAttribute vs import PackageOrModule ... where it can be pointed out that the PackageOrModule 'dotted path' argument follows the *same* rules in both cases (except for relative paths). The *salient* contrast is that only the 'from' form has a *second* argument which can be an attribute. 5. Footnote: (somewhat unrelated, but...) says "the execution of a module-level function enters the function name in the module’s global symbol table." This is surely incorrect -- it is the execution of the function's *def* that enters the function name in the symbol table. Standard Library Reference --------------------------- 1) 27.13. site — Site-specific configuration hook http://docs.python.org/py3k/library/site.html This is documentation for site.py, and is a page that might well come up in a search for '.pth'. 1a) This page may simply be importing the docstring from site.py? In any case it repeats the ommissions and errors noted above for site.py. 2) 27.1. sys — System-specific parameters and functions http://docs.python.org/py3k/library/sys.html Documentation for sys.path. OK as far as it goes, but: 2a) Could helpfully point to a discussion of the typical items to be found in sys.path under normal circumstances 2b) It does point to the site.py module documentation as the authoritative info on using .pth files (which is seriously flawed as noted above). 3) 29.3. pkgutil — Package extension utility. http://docs.python.org/py3k/library/pkgutil.html 3a) The info for pkgutil.extend_path() describes how .pkg files are similar to .pth files, and their entries should point to package directories. As I noted above, so far as I can see, package directories should be within a directory on sys,path, but should not themselves be included in the path, otherwise it breaks their capability to work properly as packages. 'Installing Python Modules' document: -------------------------------------- http://docs.python.org/py3k/install/index.html This may well be consulted for info on how to organize source files, though it is basically the doc for Distutils. 1. Main problem is that it seems quite out-of-date; "Windows has no concept of a user’s home directory, " and so on. 2. 'How installation works' > table. For Windows suggests 'prefix' (default: C:\Python) as an installation directory. This is indeed one of the possible 'site-package' directories, but surely it is deprecated in favor of C:\Python\Lib\site-packages, which this section does not mention. 3. Does not mention user-specific site-package directories. 4. 'Modifying Python's Search Path' > "The most convenient way is to add a path configuration file to a directory that’s already on Python’s path". This is incorrect. (a) .pth files are only processed in site-package directories. (b) Clarifying an additional point of confusion -- as a consequence of (a) .pth files cannot be chained. 5. Points to docs for site.py... with it's flaws noted above. PEP 302 New Import Hooks ------------------------ Given the vagueness elsewhere in the docs, one might go hunting for ground truth in the PEPs. One must allow for PEPs having been superceeded, but nonetheless, outdated info that is now wrong is an additional stumbling block for learners. 1. Section 'Specification part 1: The importer Protocol'. Discussion says that in an import statement, a path (with no leading '.') is first treated as relative. This is now incorrect (as spelled out in PEP 328.) It would be helpful to insert a note in PEP 302 pointing out that the later revision invalidates this passage. ---------- assignee: docs@python components: Documentation messages: 130964 nosy: docs@python, gwideman priority: normal severity: normal status: open title: Docs for: import, packages, site.py, .pth files type: behavior versions: Python 3.1, Python 3.2, Python 3.3 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue11553> _______________________________________

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[issue9938] Documentation for argparse interactive use
by Jay T Sept. 12, 2019

Sept. 12, 2019

New submission from Jay T <jaytula(a)gmail.com>: I want to create a custom interactive shell where I continually do parse_args. Like the following: parser = argparse.ArgumentParser() command = raw_input() while(True): args = parser.parse_args(shlex.split(command)) # Do some magic stuff command = raw_input() The problem is that if I give it invalid input, it errors and exits with a help message. I learned from argparse-users group that you can override the exit method like the following: class MyParser(ArgumentParser): def exit(self, status=0, message=None): # do whatever you want here I would be nice to have this usage documented perhaps along with best practices for doing help messages in this scenario. ---------- assignee: docs@python components: Documentation messages: 117287 nosy: docs@python, jayt priority: normal severity: normal status: open title: Documentation for argparse interactive use type: feature request versions: Python 2.7 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue9938> _______________________________________

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[issue12077] Harmonizing descriptor protocol documentation
by Davide Rizzo Aug. 29, 2019

Aug. 29, 2019

New submission from Davide Rizzo <sorcio(a)gmail.com>: There are three sources of information for the descriptor protocol: - Data model reference (Doc/reference/datamodel.rst) - Descriptor HowTo guide (Doc/howto/descriptor.rst) - PEP 252 A developer who already knows descriptor tipically reads the first one: object.__get__(self, instance, owner) "... owner is always the owner class ..." Reading a bit further there are the ways a descriptor can be called, and the "direct call" is x.__get__(a). That is, without the third argument (owner) specified. The how-to definition is slightly different: descr.__get__(self, obj, type=None) --> value Here the arguments have different names ("type" shadowing the type bultin) and it seems to be implied that the third argument is optional. The ClassMethod example at the end of the document seems to confirm this: def __get__(self, obj, klass=None): (though another example doesn't). And the method contains an explicit check on klass being None. Also it could be confusing that through the examples in the same document many different names are used for the same argument (type, objtype, klass), and all different than the name used in the reference. Lastly the PEP is more explicit: __get__(): a function callable with one or two arguments. [...] When X is None, the optional second argument, T, should be meta-object. [...] When both X and T are specified ... One more quirk: the reference explains the distinction between data and non-data descriptors, though says nothing about __set__ raising AttributeError for read-only data descriptors. My proposal: - use the same names for __get__ arguments throughout the documentation (both the reference and the tutorial), e.g. __get__(self, instance, owner) - decide whether the third argument should be optional, or state the common usage in the reference, and fix accordingly the examples in the howto - explain data, non-data and read-only descriptors in the __set__ reference, or more simply, how the defintion of __set__ affects these things. ---------- assignee: docs@python components: Documentation messages: 135974 nosy: davide.rizzo, docs@python priority: normal severity: normal status: open title: Harmonizing descriptor protocol documentation versions: Python 2.7, Python 3.2, Python 3.3 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue12077> _______________________________________

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[issue11165] Document PyEval_Call* functions
by Nick Coghlan Aug. 8, 2019

Aug. 8, 2019

New submission from Nick Coghlan <ncoghlan(a)gmail.com>: There are currently undocumented PyEval_Call* equivalents to a number of the PyObject_Call* functions. Since there are resources out there on the web that direct people to use the currently undocumented PyEval functions, it would be good to document those properly, and recommend people typically use the PyObject_Call* variants instead (as the latter include all the stack and interpreter state integrity protection code, while the PyEval variants assume that has all already been handled). ---------- assignee: docs@python components: Documentation keywords: easy messages: 128248 nosy: docs@python, ncoghlan priority: normal severity: normal stage: needs patch status: open title: Document PyEval_Call* functions versions: Python 2.7, Python 3.2, Python 3.3 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue11165> _______________________________________

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[issue12217] Cross-link docs for faulthandler, traceback and pdb
by Éric Araujo July 13, 2019

July 13, 2019

New submission from Éric Araujo <merwok(a)netwok.org>: haypo suggested linking between traceback.print_tb and faulthandler.dump_traceback(). See also links between pdb and faulthandler could also be nice, if they explain briefly how the modules differ. ---------- assignee: docs@python components: Documentation keywords: easy messages: 137298 nosy: docs@python, eric.araujo, haypo priority: normal severity: normal stage: needs patch status: open title: Cross-link docs for faulthandler, traceback and pdb versions: Python 3.3 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue12217> _______________________________________

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[issue10536] Enhancements to gettext docs
by Éric Araujo May 9, 2019

May 9, 2019

New submission from Éric Araujo <merwok(a)netwok.org>: A patch made for #2504 revealed a bug in gettext.rst, and I’ve found a number of other things to change in the file. This is the first patch of a series of two or three. Barry, as the original author of the module and doc, I’d like your opinion on points 3, a, and b particularly. Patch is also uploaded to Rietveld for greater convenience: http://codereview.appspot.com/3333042/ (upload.py rocks) Summary: 1) Markup: Use modern class/method directives combo (yay DRY). Mark up variable parts in :file: constructs (e.g. :file:`{domain}.mo` will cause the HTML output to use var to indicate replaceable text). Also change some ``gettext`` to :program:`gettext` for consistency. 2) Fix a typo in lngettext doc (originally included in patch by Franz Glasner for #2504). 3) I had started to remove information about private attributes (_info, _charset), advertising public getter methods instead. Then I read the description of NullTranslations and realized the information was needed for subclasses. I’ve reverted my removals, but I still think the private attributes should be listed in a specific section for people writing subclasses and not in the rest of the text. If you’re okay, I’ll make a second patch. 4) Assorted wording changes, missing periods and hyphens, and other very small touch-ups: Turned a broken bare link into a working link with nice text; used the with statement in an example (we all love the with statement!); used two spaces after periods throughout (hello Fred Drake). Final note: lines have not been rewrapped, for diff clarity. When I commit part or all of this patch, I’ll make another commit to rewrap. Not addressed: a) The current docs is currently POSIX-specific. b) The docs take great care to explain that Unicode strings will be returned in different places, but this should not be so accented in 3.x docs IMO. I would just put a note somewhere near the top that all strings are str and remove the redundant sentences. Following that line of thought, I could group all l*gettext variants at the end of the list of methods, explaining that regular usage should just be happy with str objects and that l*gettext are available if people really want bytes. c) The file uses “built-in namespace” and “builtins namespace”, sometimes in neighbor paragraphs. :mod:`builtins` is not used, even in explanations of the install function/method. I don’t know if I should change that. d) Some capitalization patterns look strange to me: I have seen “I18N” and “L10N” in upper case nowhere else. Similarly, lower-case “id” looks stranger than “ID”. The latter is used for example in official GNU gettext docs. Am I going into foolish consistency territory or not? Thanks in advance for reviews and opinions. ---------- assignee: eric.araujo components: Documentation files: gettext-docs-1.diff keywords: needs review, patch messages: 122420 nosy: barry, docs@python, eric.araujo priority: normal severity: normal stage: patch review status: open title: Enhancements to gettext docs versions: Python 2.7, Python 3.1, Python 3.2 Added file: http://bugs.python.org/file19819/gettext-docs-1.diff _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue10536> _______________________________________

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[issue12188] PEP 7, C style: add ++ policy and explanation
by Terry J. Reedy May 9, 2019

May 9, 2019

New submission from Terry J. Reedy <tjreedy(a)udel.edu>: In response to a discussion of a patch removing 'useless' post-increments, (which issue has apparently come up before) Guido posted "> Sorry to butt in here, but I agree with Eric that it was better > before. There is a common idiom, *pointer++ =<something>, and > whenever you see that you know that you are appending something to an > output buffer. Perhaps the most important idea here is that this > maintains the *invariant* "pointer points just after the last thing in > the buffer". Always maintaining the invariant is better than trying to > micro-optimize things so as to avoid updating dead values. The > compiler is better at that." A condensed version of the above added to PEP 7 would help new developers see the usage as local idiom rather than style bug. ---------- assignee: docs@python components: Documentation messages: 136991 nosy: docs@python, terry.reedy priority: normal severity: normal status: open title: PEP 7, C style: add ++ policy and explanation _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue12188> _______________________________________

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[issue11001] Various obvious errors in cookies documentation
by Luke Plant May 7, 2019

May 7, 2019

New submission from Luke Plant <L.Plant.98(a)cantab.net>: Docs for SimpleCookie, BaseCookie.value_encode and BaseCookie.value_decode are obviously incorrect. Attempt at patch attached. The error has existed in every Python version I've seen, I've tagged the ones I believe can receive fixes, sorry if I've made a mistake. Thanks. ---------- assignee: docs@python components: Documentation files: http_cookies_doc_corrections.diff keywords: patch messages: 126962 nosy: docs@python, spookylukey priority: normal severity: normal status: open title: Various obvious errors in cookies documentation versions: Python 2.7, Python 3.1, Python 3.2 Added file: http://bugs.python.org/file20507/http_cookies_doc_corrections.diff _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue11001> _______________________________________

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[issue10789] Lock.acquire documentation is misleading
by Jyrki Pulliainen April 26, 2019

April 26, 2019

New submission from Jyrki Pulliainen <jyrki(a)dywypi.org>: In threading module, the Lock.acquire documentation is misleading. The signature suggests that the blocking can be given as a keyword argument but that would lead to an TypeError, as thread.lock.acquire does not accept keyword arguments. The signature in documentation should be formatted as in thread.lock.acquire. ---------- assignee: docs@python components: Documentation messages: 124861 nosy: Jyrki.Pulliainen, docs@python priority: normal severity: normal status: open title: Lock.acquire documentation is misleading versions: Python 2.7, Python 3.1 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue10789> _______________________________________

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[issue10048] urllib.request documentation confusing
by Antoine Pitrou April 26, 2019

April 26, 2019

New submission from Antoine Pitrou <pitrou(a)free.fr>: The urllib.request documentation intermingles old 2.x urllib (FancyURLopener, etc.) with urllib2-inherited (*Handler, build_opener, etc.) primitives without making any distinction. This makes it rather confusing for the reader to figure out which ones to use. Ideally, the use of the old primitives should also be discouraged. ---------- assignee: docs@python components: Documentation messages: 118179 nosy: docs@python, orsenthil, pitrou priority: normal severity: normal stage: needs patch status: open title: urllib.request documentation confusing versions: Python 3.1, Python 3.2 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue10048> _______________________________________

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