Re: [Python-Dev] Static checker for common Python programming errors
Please also check python-static-type-check...@googlegroups.com. On Nov 18, 2014 3:06 AM, "Stefan Bucur" wrote: > Thanks for the pointer! There seem indeed to be more formal analysis tools > for JavaScript than for Python (e.g., the most recent one for JS I know of > is the Jalangi framework [1]). I assume the main reason is that JavaScript > is standardized and somewhat simpler, so it's easier to construct formal > specs for all language features than it is for Python, which is also > evolving faster and relies on a lot of hard-to-model native functionality. > > That's why I'm planning to reuse as much as possible the "implicit specs" > of the interpreter implementation, instead of re-stating them in an > explicit model. > > We already have an execution engine that uses the interpreter to > automatically explore multiple paths through a piece of Python code (you > can read here [2] the academic paper, with case studies for Python and > Lua). In turn, we could use that engine to discover paths, while checking > program properties along each path. > > Guido's suggestion for a type checker raises some interesting applications > of this multi-path analysis. For instance, we could examine the type of the > objects assigned to a static variable across all discovered execution paths > and determine its consistency. This analysis could either start with no > type annotations and output suggested types, or take existing annotations > and check them against the actual types. > > Thanks again, > Stefan > > [1] https://github.com/SRA-SiliconValley/jalangi > [2] http://dslab.epfl.ch/pubs/chef.pdf > > On Mon Nov 17 2014 at 8:50:21 PM Francis Giraldeau < > francis.girald...@gmail.com> wrote: > >> If I may, there are prior work on JavaScript that may be worth >> investigating. Formal verification of dynamically typed software is a >> challenging endeavour, but it is very valuable to avoid errors at runtime, >> providing benefits from strongly type language without the rigidity. >> >> http://cs.au.dk/~amoeller/papers/tajs/ >> >> Good luck! >> >> Francis >> >> 2014-11-17 9:49 GMT-05:00 Stefan Bucur : >> >>> I'm developing a Python static analysis tool that flags common >>> programming errors in Python programs. The tool is meant to complement >>> other tools like Pylint (which perform checks at lexical and syntactic >>> level) by going deeper with the code analysis and keeping track of the >>> possible control flow paths in the program (path-sensitive analysis). >>> >>> For instance, a path-sensitive analysis detects that the following >>> snippet of code would raise an AttributeError exception: >>> >>> if object is None: # If the True branch is taken, we know the object is >>> None >>> object.doSomething() # ... so this statement would always fail >>> >>> I'm writing first to the Python developers themselves to ask, in their >>> experience, what common pitfalls in the language & its standard library >>> such a static checker should look for. For instance, here [1] is a list of >>> static checks for the C++ language, as part of the Clang static analyzer >>> project. >>> >>> My preliminary list of Python checks is quite rudimentary, but maybe >>> could serve as a discussion starter: >>> >>> * Proper Unicode handling (for 2.x) >>> - encode() is not called on str object >>> - decode() is not called on unicode object >>> * Check for integer division by zero >>> * Check for None object dereferences >>> >>> Thanks a lot, >>> Stefan Bucur >>> >>> [1] http://clang-analyzer.llvm.org/available_checks.html >>> >>> >>> ___ >>> Python-Dev mailing list >>> Python-Dev@python.org >>> https://mail.python.org/mailman/listinfo/python-dev >>> >> Unsubscribe: >>> https://mail.python.org/mailman/options/python-dev/francis.giraldeau%40gmail.com >>> >>> >> > ___ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/guido%40python.org > > ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Static checker for common Python programming errors
Thanks for the pointer! There seem indeed to be more formal analysis tools for JavaScript than for Python (e.g., the most recent one for JS I know of is the Jalangi framework [1]). I assume the main reason is that JavaScript is standardized and somewhat simpler, so it's easier to construct formal specs for all language features than it is for Python, which is also evolving faster and relies on a lot of hard-to-model native functionality. That's why I'm planning to reuse as much as possible the "implicit specs" of the interpreter implementation, instead of re-stating them in an explicit model. We already have an execution engine that uses the interpreter to automatically explore multiple paths through a piece of Python code (you can read here [2] the academic paper, with case studies for Python and Lua). In turn, we could use that engine to discover paths, while checking program properties along each path. Guido's suggestion for a type checker raises some interesting applications of this multi-path analysis. For instance, we could examine the type of the objects assigned to a static variable across all discovered execution paths and determine its consistency. This analysis could either start with no type annotations and output suggested types, or take existing annotations and check them against the actual types. Thanks again, Stefan [1] https://github.com/SRA-SiliconValley/jalangi [2] http://dslab.epfl.ch/pubs/chef.pdf On Mon Nov 17 2014 at 8:50:21 PM Francis Giraldeau < francis.girald...@gmail.com> wrote: > If I may, there are prior work on JavaScript that may be worth > investigating. Formal verification of dynamically typed software is a > challenging endeavour, but it is very valuable to avoid errors at runtime, > providing benefits from strongly type language without the rigidity. > > http://cs.au.dk/~amoeller/papers/tajs/ > > Good luck! > > Francis > > 2014-11-17 9:49 GMT-05:00 Stefan Bucur : > >> I'm developing a Python static analysis tool that flags common >> programming errors in Python programs. The tool is meant to complement >> other tools like Pylint (which perform checks at lexical and syntactic >> level) by going deeper with the code analysis and keeping track of the >> possible control flow paths in the program (path-sensitive analysis). >> >> For instance, a path-sensitive analysis detects that the following >> snippet of code would raise an AttributeError exception: >> >> if object is None: # If the True branch is taken, we know the object is >> None >> object.doSomething() # ... so this statement would always fail >> >> I'm writing first to the Python developers themselves to ask, in their >> experience, what common pitfalls in the language & its standard library >> such a static checker should look for. For instance, here [1] is a list of >> static checks for the C++ language, as part of the Clang static analyzer >> project. >> >> My preliminary list of Python checks is quite rudimentary, but maybe >> could serve as a discussion starter: >> >> * Proper Unicode handling (for 2.x) >> - encode() is not called on str object >> - decode() is not called on unicode object >> * Check for integer division by zero >> * Check for None object dereferences >> >> Thanks a lot, >> Stefan Bucur >> >> [1] http://clang-analyzer.llvm.org/available_checks.html >> >> >> ___ >> Python-Dev mailing list >> Python-Dev@python.org >> https://mail.python.org/mailman/listinfo/python-dev >> > Unsubscribe: >> https://mail.python.org/mailman/options/python-dev/francis.giraldeau%40gmail.com >> >> > ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Static checker for common Python programming errors
On 2014-11-18 01:21, Terry Reedy wrote: On 11/17/2014 9:49 AM, Stefan Bucur wrote: I'm developing a Python static analysis tool that flags common programming errors in Python programs. The tool is meant to complement other tools like Pylint (which perform checks at lexical and syntactic level) by going deeper with the code analysis and keeping track of the possible control flow paths in the program (path-sensitive analysis). For instance, a path-sensitive analysis detects that the following snippet of code would raise an AttributeError exception: if object is None: # If the True branch is taken, we know the object is None object.doSomething() # ... so this statement would always fail I'm writing first to the Python developers themselves to ask, in their experience, what common pitfalls in the language & its standard library such a static checker should look for. For instance, here [1] is a list of static checks for the C++ language, as part of the Clang static analyzer project. You could also a) ask on python-list (new thread), or scan python questions on StackOverflow. Todays's example: "Why does my function return None?" Because there is no return statement. Perhaps current checkers can note that, but what about if some branches have a return and others do not? That is a likely bug. Mutable default parameters comes up occasionally. ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Static checker for common Python programming errors
On 11/17/2014 9:49 AM, Stefan Bucur wrote: I'm developing a Python static analysis tool that flags common programming errors in Python programs. The tool is meant to complement other tools like Pylint (which perform checks at lexical and syntactic level) by going deeper with the code analysis and keeping track of the possible control flow paths in the program (path-sensitive analysis). For instance, a path-sensitive analysis detects that the following snippet of code would raise an AttributeError exception: if object is None: # If the True branch is taken, we know the object is None object.doSomething() # ... so this statement would always fail I'm writing first to the Python developers themselves to ask, in their experience, what common pitfalls in the language & its standard library such a static checker should look for. For instance, here [1] is a list of static checks for the C++ language, as part of the Clang static analyzer project. You could also a) ask on python-list (new thread), or scan python questions on StackOverflow. Todays's example: "Why does my function return None?" Because there is no return statement. Perhaps current checkers can note that, but what about if some branches have a return and others do not? That is a likely bug. -- Terry Jan Reedy ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Static checker for common Python programming errors
If I may, there are prior work on JavaScript that may be worth investigating. Formal verification of dynamically typed software is a challenging endeavour, but it is very valuable to avoid errors at runtime, providing benefits from strongly type language without the rigidity. http://cs.au.dk/~amoeller/papers/tajs/ Good luck! Francis 2014-11-17 9:49 GMT-05:00 Stefan Bucur : > I'm developing a Python static analysis tool that flags common programming > errors in Python programs. The tool is meant to complement other tools like > Pylint (which perform checks at lexical and syntactic level) by going > deeper with the code analysis and keeping track of the possible control > flow paths in the program (path-sensitive analysis). > > For instance, a path-sensitive analysis detects that the following snippet > of code would raise an AttributeError exception: > > if object is None: # If the True branch is taken, we know the object is > None > object.doSomething() # ... so this statement would always fail > > I'm writing first to the Python developers themselves to ask, in their > experience, what common pitfalls in the language & its standard library > such a static checker should look for. For instance, here [1] is a list of > static checks for the C++ language, as part of the Clang static analyzer > project. > > My preliminary list of Python checks is quite rudimentary, but maybe could > serve as a discussion starter: > > * Proper Unicode handling (for 2.x) > - encode() is not called on str object > - decode() is not called on unicode object > * Check for integer division by zero > * Check for None object dereferences > > Thanks a lot, > Stefan Bucur > > [1] http://clang-analyzer.llvm.org/available_checks.html > > > ___ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/francis.giraldeau%40gmail.com > > ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Static checker for common Python programming errors
On Mon Nov 17 2014 at 12:06:15 PM Stefan Bucur wrote: > Mark, thank you for the pointer! I will re-send my message there. Should I > include both mailing lists in a single thread if I end up receiving replies > from both? No as cross-posting becomes just a nightmare of moderation when someone is not on both lists; please only post to a single mailing list. -Brett > > Cheers, > Stefan > > > On Mon Nov 17 2014 at 4:04:45 PM Mark Shannon wrote: > >> Hi, >> >> I think this might be a bit off-topic for this mailing list, >> code-qual...@python.org is the place for discussing static analysis >> tools. >> >> Although if anyone does have any comments on any particular checks >> they would like, I would be interested as well. >> >> Cheers, >> Mark. >> >> >> On 17/11/14 14:49, Stefan Bucur wrote: >> > I'm developing a Python static analysis tool that flags common >> > programming errors in Python programs. The tool is meant to complement >> > other tools like Pylint (which perform checks at lexical and syntactic >> > level) by going deeper with the code analysis and keeping track of the >> > possible control flow paths in the program (path-sensitive analysis). >> > >> > For instance, a path-sensitive analysis detects that the following >> > snippet of code would raise an AttributeError exception: >> > >> > if object is None: # If the True branch is taken, we know the object is >> None >> >object.doSomething() # ... so this statement would always fail >> > >> > I'm writing first to the Python developers themselves to ask, in their >> > experience, what common pitfalls in the language & its standard library >> > such a static checker should look for. For instance, here [1] is a list >> > of static checks for the C++ language, as part of the Clang static >> > analyzer project. >> > >> > My preliminary list of Python checks is quite rudimentary, but maybe >> > could serve as a discussion starter: >> > >> > * Proper Unicode handling (for 2.x) >> >- encode() is not called on str object >> >- decode() is not called on unicode object >> > * Check for integer division by zero >> > * Check for None object dereferences >> > >> > Thanks a lot, >> > Stefan Bucur >> > >> > [1] http://clang-analyzer.llvm.org/available_checks.html >> > >> > >> > >> > ___ >> > Python-Dev mailing list >> > Python-Dev@python.org >> > https://mail.python.org/mailman/listinfo/python-dev >> > Unsubscribe: https://mail.python.org/mailman/options/python-dev/ >> mark%40hotpy.org >> > >> > ___ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: https://mail.python.org/mailman/options/python-dev/ > brett%40python.org > ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Static checker for common Python programming errors
Also, I should mention mypy (mypy-lang.org), which is a much more ambitious project that uses type annotations. I am trying to find time to work on a PEP that standardizes type annotations to match mypy's syntax (with probably some improvements and caveats). It's too early to post the PEP draft but if you're designing a type checker or IDE that could use help from type annotations, email me. On Mon, Nov 17, 2014 at 6:49 AM, Stefan Bucur wrote: > I'm developing a Python static analysis tool that flags common programming > errors in Python programs. The tool is meant to complement other tools like > Pylint (which perform checks at lexical and syntactic level) by going > deeper with the code analysis and keeping track of the possible control > flow paths in the program (path-sensitive analysis). > > For instance, a path-sensitive analysis detects that the following snippet > of code would raise an AttributeError exception: > > if object is None: # If the True branch is taken, we know the object is > None > object.doSomething() # ... so this statement would always fail > > I'm writing first to the Python developers themselves to ask, in their > experience, what common pitfalls in the language & its standard library > such a static checker should look for. For instance, here [1] is a list of > static checks for the C++ language, as part of the Clang static analyzer > project. > > My preliminary list of Python checks is quite rudimentary, but maybe could > serve as a discussion starter: > > * Proper Unicode handling (for 2.x) > - encode() is not called on str object > - decode() is not called on unicode object > * Check for integer division by zero > * Check for None object dereferences > > Thanks a lot, > Stefan Bucur > > [1] http://clang-analyzer.llvm.org/available_checks.html > > > ___ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/guido%40python.org > > -- --Guido van Rossum (python.org/~guido) ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Static checker for common Python programming errors
Mark, thank you for the pointer! I will re-send my message there. Should I include both mailing lists in a single thread if I end up receiving replies from both? Cheers, Stefan On Mon Nov 17 2014 at 4:04:45 PM Mark Shannon wrote: > Hi, > > I think this might be a bit off-topic for this mailing list, > code-qual...@python.org is the place for discussing static analysis tools. > > Although if anyone does have any comments on any particular checks > they would like, I would be interested as well. > > Cheers, > Mark. > > > On 17/11/14 14:49, Stefan Bucur wrote: > > I'm developing a Python static analysis tool that flags common > > programming errors in Python programs. The tool is meant to complement > > other tools like Pylint (which perform checks at lexical and syntactic > > level) by going deeper with the code analysis and keeping track of the > > possible control flow paths in the program (path-sensitive analysis). > > > > For instance, a path-sensitive analysis detects that the following > > snippet of code would raise an AttributeError exception: > > > > if object is None: # If the True branch is taken, we know the object is > None > >object.doSomething() # ... so this statement would always fail > > > > I'm writing first to the Python developers themselves to ask, in their > > experience, what common pitfalls in the language & its standard library > > such a static checker should look for. For instance, here [1] is a list > > of static checks for the C++ language, as part of the Clang static > > analyzer project. > > > > My preliminary list of Python checks is quite rudimentary, but maybe > > could serve as a discussion starter: > > > > * Proper Unicode handling (for 2.x) > >- encode() is not called on str object > >- decode() is not called on unicode object > > * Check for integer division by zero > > * Check for None object dereferences > > > > Thanks a lot, > > Stefan Bucur > > > > [1] http://clang-analyzer.llvm.org/available_checks.html > > > > > > > > ___ > > Python-Dev mailing list > > Python-Dev@python.org > > https://mail.python.org/mailman/listinfo/python-dev > > Unsubscribe: https://mail.python.org/mailman/options/python-dev/ > mark%40hotpy.org > > > ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Static checker for common Python programming errors
Hi, I think this might be a bit off-topic for this mailing list, code-qual...@python.org is the place for discussing static analysis tools. Although if anyone does have any comments on any particular checks they would like, I would be interested as well. Cheers, Mark. On 17/11/14 14:49, Stefan Bucur wrote: I'm developing a Python static analysis tool that flags common programming errors in Python programs. The tool is meant to complement other tools like Pylint (which perform checks at lexical and syntactic level) by going deeper with the code analysis and keeping track of the possible control flow paths in the program (path-sensitive analysis). For instance, a path-sensitive analysis detects that the following snippet of code would raise an AttributeError exception: if object is None: # If the True branch is taken, we know the object is None object.doSomething() # ... so this statement would always fail I'm writing first to the Python developers themselves to ask, in their experience, what common pitfalls in the language & its standard library such a static checker should look for. For instance, here [1] is a list of static checks for the C++ language, as part of the Clang static analyzer project. My preliminary list of Python checks is quite rudimentary, but maybe could serve as a discussion starter: * Proper Unicode handling (for 2.x) - encode() is not called on str object - decode() is not called on unicode object * Check for integer division by zero * Check for None object dereferences Thanks a lot, Stefan Bucur [1] http://clang-analyzer.llvm.org/available_checks.html ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/mark%40hotpy.org ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
