On 1/31/20 10:58 PM, Andrew Barnert via Python-ideas wrote:
When refactoring code to rename something, there is no way to tell
whether a string—or a substring in a larger string—that matches the
name should be changed. But a nameof expression is unambiguously a
reference to the name, and therefore the tool knows that it needs to
change.
Thinking about this, I have a question, IS there existing a refactoring
program that can do the rest of the job in Python well. I am not sure
there can be.
Take an example refactoring problem: We have a logging module to save
diagnostic information about program operation. The logging class
currently has a member log that we want to change to log_file.
In a statically type language, this is fairly easy, scan through the
source code, find all references to the symbol log, see if they refer to
the logging module or something else (which is easily solvable in a
statically typed language, as the compiler needs to do this) and if they
refer to the logging module, change the reference. The refactoring
program just needs about the same smarts as the compiler.
We can't easily do this in Python. In general, we come to the sequence
foo.log, in order to determine if we want to change this, we need to
know what foo will be every time it gets there. To determine this we
need to back track to figure every path of execution to here.
In fact, the transformation may not be possible (or may require other
changes beyond what we want) as there may be a usage that handles many
different types, all that happen to have a log member, so to change one
class, we need to change them all (this can also happen in C++ templates
which also can use duck typing). This lack of local type information
makes the refactoring MUCH harder, and as you make the program smart
enough to work on handling this, including strings might not be that
hard. My guess is that any such refactoring is going to need to ask the
programmer about a number of cases of the usage that the program can't
determine, and thus can include strings that match too.
--
Richard Damon
_______________________________________________
Python-ideas mailing list -- python-ideas@python.org
To unsubscribe send an email to python-ideas-le...@python.org
https://mail.python.org/mailman3/lists/python-ideas.python.org/
Message archived at
https://mail.python.org/archives/list/python-ideas@python.org/message/TJLFZANF54K7JZM6NBQC3JI7GCCUKKPV/
Code of Conduct: http://python.org/psf/codeofconduct/
